This article is about the practice of meditation. For the writings by Marcus Aurelius, see Meditations. For the writings by René Descartes, see Meditations on First Philosophy.

Meditation is the practice of focusing the mind, often formalized into a specific routine. Meditation is usually recognized as a component of Eastern religions, originating in Vedic Hinduism, but it also developed independently in Sufism. It encompasses any of a wide variety of spiritual practices which emphasize mental activity or quiescence. Meditation can also be used for personal development in a non-religious context, such as the exercises of Hatha yoga.

Contents 1 Overview 2 Types of meditation 2.1 Buddhism 2.2 Christianity 2.3 Judaism 2.4 Hinduism 2.5 Islam 2.6 Sikhism 2.7 Taoism 2.8 Transcendental Meditation 2.9 Secular 3 Meditation in context 4 Physical postures 5 Frequency and duration 6 Purposes and effects of meditation 7 Metta meditation: the practice of loving-kindness 8 Health applications and clinical studies of meditation 8.1 Meditation and the brain 8.2 Meditation and EEG's 8.3 Adverse effects 8.4 Meditation and drugs 9 See also 10 References 11 External links

Overview

The English word meditation comes from the Latin meditatio, which originally indicated every type of physical or intellectual exercise, then later evolved into the more specific meaning "contemplation." This usage is found in Christian spirituality, for example, "meditations on the sufferings of Christ"; as well as Western philosophy, as in Descartes' Meditations on First Philosophy, a set of six mental exercises which systematically analyze the nature of reality.

However, "meditation" in its modern sense also refers to a separate practice unrelated to Christian meditations. In the late nineteenth century, Theosophists adopted the word "meditation" to refer to various spiritual practices drawn from Hinduism, Buddhism, and other Eastern religions. Thus the English word "meditation" does not exclusively translate any single term or concept, and can be used to translate words such as the Sanskrit dhyana, samadhi, or pranayama.

Meditation is usually defined as one of the following:

• a state that is experienced when the mind dissolves and is free of all thoughts
• focusing the mind on a single object (such as a religious statue, or one's breath, or a mantra)
• a mental "opening up" to the divine, invoking the guidance of a higher power
• reasoned analysis of religious teachings (such as impermanence, for Buddhists).

Its ritual and contemplative qualities are similar to prayer in Western religions, but prayer emphasizes communication with a higher being, whereas meditation focuses on developing oneself.

Meditation may be for a religious purpose, but even before being brought to the West it was used in secular contexts, such as the martial arts. Beginning with the Theosophists, though, meditation has been employed by a number of religious movements, such as Hatha yoga and the New Age movement, as well as limited use in Christianity. It has been suggested that the recent popularity of "meditation" as a religious practice in the West signals some discomfort with more traditional Christian and Jewish practices such as prayer. Others see meditation and prayer as harmonious: Edgar Cayce taught that "Through prayer we speak to God. In meditation, God speaks to us."

From the point of view of psychology, meditation can induce an altered state of consciousness. However, many religious people would challenge the assumption that such mental states (or any other visible result) are the "goal" of meditation. The goals of meditation are varied, and range from spiritual enlightenment, to the transformation of attitudes, to better cardiovascular health.

It is easy to observe that our minds are continually thinking about the past (memories) and the future (expectations). With intention, it is possible to slow down the mind. We are able to observe a mental silence, also called experience of the present moment. This is a subjective sense of being connected with the universality of being. Meditation is the method one may follow to verify this experience. It is an experiential means of separating thoughts from the part of our consciousness which perceives the thoughts, the observer. By disengaging our mind, we are able to observe the more subtle details and gain better control over what we give attention to. The experience of thoughts winding down and stopping is also known as timeless awareness.

Types of meditation

According to Perez-De-Albeniz & Holmes (2000), the different techniques of meditation can be classified according to their focus. Some focus on the field or background perception and experience, also called mindfulness; others focus on a preselected specific object, and are called "'concentrative' meditation." There are also techniques that shift between the field and the object.

Categorizing the varieties of meditation is difficult. One common way is according to religion or lineage. But some meditative traditions, such as yoga or tantra, are common to several religions or occur outside religious contexts. Therefore, to avoid controversy, this article will not attempt to classify all meditations into a religious class or lineage.

Buddhism

Main article: Buddhist meditation

Meditation has always enjoyed a central place within Buddhism. The Buddha himself was said to have achieved enlightenment while meditating under a Bodhi tree. Most forms of Buddhism distinguish between samatha and vipassana meditation, both of which are necessary for enlightenment. The former consists of learning to focus the attention single-pointedly; the latter involves seeing the true nature of reality.

Theravada Buddhism emphasizes vipassana meditation directed towards anapana, mettā bhāvanā, or 38 other traditional topics (see: Kammatthana).

In Japanese Mahayana schools, Tendai (Tien-tai), concentration is cultivated through highly structured ritual. Especially in the Chinese Chan Buddhism school (which branched out into the Japanese Zen, and Korean Seon schools), ts'o ch'an meditation and kung an meditation practices are extremely important and considered a necessity for enlightenment (each of the names of these schools derives from the sanskrit dhyana, and translates into "meditation" in their respective languages). The esoteric Shingon sect shares many features with Tibetan Buddhism.

Tibetan Buddhism emphasizes tantra for its senior practitioners; hence its alternate name of Vajrayana Buddhism. However, visitors to Tibetan monasteries are often surprised to discover that many monks go through their day without "meditating" in a recognizable form, but are more likely to chant or participate in group liturgy.

Christianity

Main article: Christian meditation

Christian traditions have various practices which might be identified as forms of "meditation." Many of these are monastic practices. Some types of Christian prayer, such as the rosary in Catholicism or the hesychasm in Eastern Orthodoxy, may be compared to the form of Eastern meditation that focuses on an individual object, but these comparisons often overlook the importance of prayer in these rituals.

Judaism

The explicit concept of meditation, or in-depth contemplation (Hebrew hitbonenut) can be found in Kabbalah and Hassidic Judaism.

Hinduism

There are several types of meditation in Hinduism.

• Vedanta is a form of Jnana Yoga.
• Raja Yoga, as outlined by Patanjali, describes eight "limbs" of spiritual practices, half of which might be classified as meditation. Underlying them is the assumption that a yogi should still the fluctuations of his or her mind: Yoga cittavrrti nirodha.
• Sant Mat teaches "sound and light meditation" (surat shabd yoga)
• Osho taught a wide variety of meditative techniques, including a "laughing meditation".

Islam

Main article: Muraqaba

Within Islam, "meditation" refers to the Sufi practice of muraqaba. Similar forms of meditative ritual in Sufism include dhikr (recitation of the divine names), sema, whirling, and devotional music such as Qawwali.

Sikhism

Main article: Nām Japō

In Sikhism, the practices of simran and Nām Japō encourage quiet meditation.

Taoism

Taoism includes a number of meditative and contemplative traditions. Originally said to have their principles described in the I Ching, Tao Te Ching, Chuang Tzu and Tao Tsang among other texts; the multitude of schools relating to Qigong, Neigong, Daoyin and Zhan zhuang are a large, diverse array of breath training practises in aid of meditation with much influence from later Chinese Buddhism and with much influence on traditional Chinese medicine and the Chinese as well as some Japanese martial arts. The Chinese martial art T'ai Chi Ch'uan is named after the well-known focus for Taoist and Neo-Confucian meditation, the T'ai Chi T'u, and is often referred to as “meditation in motion”.

Transcendental Meditation

Main article: Transcendental Meditation

Transcendental Meditation is a modern form of meditation invented by Maharishi Mahesh Yogi, an Indian spiritual teacher. It is grounded in Vedantic Hinduism, but also has its own innovations. Transcendental Meditation is based on a mantra, which is given to the practitioner by the teacher.

Secular

Forms of meditation which are devoid of mystical content have been developed in the west as a way of promoting physical and mental well being. Most notable is Autogenic training developed by the German psychiatrist Johannes Schultz in 1932.

Meditation in context

Most traditions address the integration of mind, body, and spirit (this is a major theme of the Bhagavad-Gita); or that of spiritual practice with family life, work, and so on. Often, meditation is said to be incomplete if it doesn't lead to positive changes in one's daily life and attitudes. In that spirit some Zen practitioners have promoted "Zen driving," aimed at reducing road rage.

Meditation is often presented not as a "free-standing" activity, but as one part of a wider spiritual tradition. Nevertheless, many meditators today do not follow an organized religion, or do not consider themselves to do so faithfully. Religious authorities typically insist that spiritual practices such as meditation belong in the context of a well-rounded religious life that may include ritual or liturgy, scriptural study, and the observance of religious laws or regulations.

Perhaps the most widely-cited spiritual prerequisite for meditation is an ethical lifestyle. Many martial arts teachers urge their students to respect parents and teachers, and inculcate other positive values. Some traditions incorporate "crazy wisdom" or intentionally transgressive acts, in their sacred lore if not in actual practice. Sufi poets (e.g. Rumi, Hafiz) celebrate the virtues of wine, which is forbidden in Islam (though one could argue that the poets are speaking metaphorically); some tantrikas indulge in the "five forbidden things that begin with the letter M."^{[citation needed]}

Most meditative traditions discourage drug use. Exceptions include some forms of Hinduism, which have a long tradition of hashish or marijuana-using renunciates; and certain Native American traditions, which use peyote, ayahuasca, or other restricted substances in a religious setting.

A number of meditative traditions requires permission from a teacher or elder, who in turn has received permission from another teacher, and so on, in a lineage. Most Chinese traditions rely on the Confucian concept of a Sifu. Hinduism and Buddhism stress the importance of a spiritual teacher (Sanskrit guru, Tibetan lama). Orthodox Christianity has "spiritual elders" (Greek gerontas, Russian starets); Catholic religious have spiritual directors.

The immediate meditative environment is often held to be important. Several traditions incorporate cleansing rituals for the place where one meditates, and others offer instructions for an altar or other accessories.

Physical postures

Different spiritual traditions, and different teachers within those traditions, prescribe or suggest different physical postures for meditation. Most famous are the several cross-legged postures, including the so-called Lotus Position. For example, the Dalai Lama recommends the Seven Points of Vairocana in which

• the legs are crossed in either the Lotus Position (here called the vajra position) or the other way, "Indian" or "tailor" fashion (here called the bodhisattva position)
• the eyes are kept open (thus affirming the world)
• the back is kept straight (like "an arrow" or "a stack of coins")
• the shoulders are kept even and relaxed
• the gaze is kept at a medium level—too low and one becomes drowsy; too high and one becomes restless
• the mouth is kept slightly open
• the tongue touches the roof of the mouth

Many meditative traditions teach that the spine should be kept "straight" (i.e. that the meditator should not slouch). Often this is explained as a way of encouraging the circulation of what we might call "spiritual energy," the "vital breath", or the "life force" (Sanskrit prana, Chinese qi, Latin spiritus). In some traditions the meditator may sit on a Western chair, flat-footed (as in New Thought); sit on a stool (as in Orthodox Christianity); or walk in mindfulness (as in Theravada Buddhism).

Various hand-gestures or mudras may be prescribed. These can carry theological meaning or according to Yogic philosophy can actually affect consciousness. For example, a common Buddhist hand-position is with the right hand resting atop the left (like the Buddha's begging bowl), with the thumbs touching.

Quiet is often held to be desirable, and some people use repetitive activities such as deep breathing, humming or chanting to help induce a meditative state. The Tibetan tradition described above is probably in the minority for recommending that the eyes remain open. Practitioners of the Soto Zen tradition also meditate with their eyes open, facing a wall, but most schools of meditation assume that the eyes will be closed.

Often such details are shared by more than one religion, even in cases where mutual influence seems unlikely. One example would be "navel-gazing," which is apparently attested within Eastern Orthodoxy as well as Chinese qigong practice. Another would be the practice of focusing on the breath, which is found in Orthodox Christianity, Sufism, and numerous Indic traditions.

Sitting cross-legged (or upon one's knees) for extended periods when one is not sufficiently limber, can result in a range of ergonomic complaints called "meditator's knee".

Frequency and duration

These vary so much that it is difficult to venture any general comments. On one extreme there exist monks and nuns whose whole lives are ordered around meditation; on the other hand, one-minute meditations are not out of the question.

Twenty or thirty minutes is probably a typical duration. Experienced meditators often find their sessions growing in length of their own accord. Observing the advice and instructions of one's spiritual teacher is generally held to be most beneficial.

Many traditions stress regular practice. Accordingly, many meditators experience guilt or frustration upon failing to do so. Possible responses range from perseverance to acceptance.

Purposes and effects of meditation

The purposes for which people meditate vary almost as widely as practices. Meditation may serve simply as a means of relaxation from a busy daily routine; as a technique for cultivating mental discipline; or as a means of gaining insight into the nature of reality, or of communing with one's God. Many report improved concentration, awareness, self-discipline and equanimity through meditation.

Many authorities avoid emphasizing the effects of meditation — sometimes out of modesty, sometimes for fear that the expectation of results might interfere with one's meditation. For theists, the effects of meditation are considered a gift of God or from the Holy Spirit/Ghost, and not something that is "achieved" by the meditator alone, just as some say that a person will not convert to Christianity without the influence of the Holy Spirit/Ghost's presence.

At the same time, many effects (or perhaps side-effects) have been experienced during, or claimed for, various types of meditation. These include:

• Greater faith in, or understanding of, one's religion or beliefs
• An increase in patience, compassion, and other virtues and morals or the understanding of them
• Feelings of calm or peace, and/or moments of great joy
• Consciousness of sin, temptation, and remorse, and a spirit of contrition.
• Sensitivity to certain forms of lighting, such as fluorescent lights or computer screens, and sometimes heightened sense-perception.
• Surfacing of buried memories, possibly including memories of previous lives and those of others, or that of those to come
• Experience of spiritual phenomena such as kundalini, extra-sensory perception, or visions of deities, saints, demons, etc.
• "Miraculous" abilities such as levitation (cf. yogic flying)
• Psychotic episodes (see medical section below)

Some traditions acknowledge that many types of experiences and effects are possible, but instruct the meditator to keep in mind the spiritual purpose of the meditation, and not be distracted by lesser concerns. For example, Mahayana Buddhists are urged to meditate for the sake of "full and perfect enlightenment for all sentient beings" (the bodhisattva vow). Some, as in certain sects of Christianity, say that these things are possible, but are only to be supported if they are to the glory of God.

Metta meditation: the practice of loving-kindness

Main article: Metta

The Pali word Metta is commonly translated in English as loving-kindness. Metta signifies friendship and non-violence as well as "a strong wish for the happiness of others." Though it refers to many seemingly disparate ideas, Metta is in fact a very specific form of love—a caring for another independent of all self-interest—and thus is likened to one's love for one's child or parent. Understandably, this energy is often difficult to describe in words; however, in the practice of Metta meditation, one recites specific words and phrases in order to evoke this "boundless warm-hearted feeling." The strength of this feeling is not limited to or by family, religion, or social class. Indeed, Metta is a tool that permits one's generosity and kindness to be applied to all beings and, as a consequence, one finds true happiness in another person's happiness, no matter who the individual is.

Health applications and clinical studies of meditation

In the recent years there has been a growing interest within the medical community to study the physiological effects of meditation (Venkatesh et al., 1997; Peng et al., 1999; Lazar et al., 2000; Carlson et.al, 2001). Many concepts of meditation have been applied to clinical settings in order to measure its effect on somatic motor function as well as cardiovascular and respiratory function. Also the hermeneutic and phenomenological aspects of meditation are areas of growing interest. Meditation has entered the mainstream of health care as a method of stress and pain reduction. For example, in an early study in 1972, transcendental meditation was shown to affect the human metabolism by lowering the biochemical byproducts of stress, such as lactate, decreasing heart rate and blood pressure and inducing favorable brain waves. (Scientific American 226: 84-90 (1972))

As a method of stress reduction, meditation is often used in hospitals in cases of chronic or terminal illness to reduce complications associated with increased stress including a depressed immune system. There is a growing consensus in the medical community that mental factors such as stress significantly contribute to a lack of physical health, and there is a growing movement in mainstream science to fund research in this area (e.g. the establishment by the NIH in the U.S. of 5 research centers to research the mind-body aspects of disease.) Dr. James Austin, a neurophysiologist at the University of Colorado, reported that Zen meditation rewires the circuitry of the brain in his landmark book Zen and the Brain (Austin, 1999). This has been confirmed using functional MRI imaging which examine the electrical activity of the brain.

Dr. Herbert Benson of the Mind-Body Medical Institute, which is affiliated with Harvard and several Boston hospitals, reports that meditation induces a host of biochemical and physical changes in the body collectively referred to as the "relaxation response" (Lazar et.al, 2003). The relaxation response includes changes in metabolism, heart rate, respiration, blood pressure and brain chemistry. Benson and his team have also done clinical studies at Buddhist monasteries in the Himalayan Mountains.

Other studies within this field include the research of Jon Kabat-Zinn and his colleagues at the University of Massachusetts who have studied the effects of mindfulness meditation on stress (Kabat-Zinn et.al, 1985; Davidson et.al, 2003).

Meditation and the brain

Mindfulness meditation and related techniques are intended to train attention for the sake of provoking insight. Think of it as the opposite of attention deficit disorder. A wider, more flexible attention span makes it easier to be aware of a situation, easier to be objective in emotionally or morally difficult situations, and easier to achieve a state of responsive, creative awareness or "flow".

One theory, presented by Daniel Goleman & Tara Bennett-Goleman (2001), suggests that meditation works because of the relationship between the amygdala and the prefrontal cortex. In very simple terms, the amygdala is the part of the brain that decides if we should get angry or anxious (among other things), and the pre-frontal cortex is the part that makes us stop and think about things (it is also known as the inhibitory centre).

So, the prefrontal cortex is very good at analyzing and planning, but it takes a long time to make decisions. The amygdala, on the other hand, is simpler (and older in evolutionary terms). It makes rapid judgements about a situation and has a powerful effect on our emotions and behaviour, linked to survival needs. For example, if a human sees a lion leaping out at them, the amygdala will trigger a fight or flight response long before the prefrontal cortex responds.

But in making snap judgments, our amygdalas are prone to error, such as seeing danger where there is none. This is particularly true in contemporary society where social conflicts are far more common than encounters with predators, and a basically harmless but emotionally charged situation can trigger uncontrollable fear or anger — leading to conflict, anxiety, and stress.

Because there is roughly a quarter of a second gap between the time an event occurs and the time it takes the amygdala to react, a skilled meditator may be able to intervene before a fight or flight response takes over, and perhaps even redirect it into more constructive or positive feelings.

The different roles of the amygdala and prefrontal cortex can be easily observed under the influence of various drugs. Alcohol depresses the brain generally, but the sophisticated prefrontal cortex is more affected than less complex areas, resulting in lowered inhibitions, decreased attention span, and increased influence of emotions over behaviour. Likewise, the controversial drug ritalin has the opposite effect, because it stimulates activity in the prefrontal cortex.

Some studies of meditation have linked the practice to increased activity in the left prefrontal cortex, which is associated with concentration, planning, meta-cognition (thinking about thinking), and positive affect (good feelings). There are similar studies linking depression and anxiety with decreased activity in the same region, and/or with dominant activity in the right prefrontal cortex. Meditation increases activity in the left prefrontal cortex, and the changes are stable over time — even if you stop meditating for a while, the effect lingers.

Meditation and EEG's

Electroencephalographs (EEG) recordings of skilled meditators showed gamma wave activity that gradually expanded across the brain during meditation. Gamma waves indicate synchrony between sections of the brain. These meditators had 10 to 40 years of training in Buddhist-based mental training. EEGs done on meditators who had received recent training turned up considerably less synchrony.

The experienced meditators also showed increased gamma activity while at rest and not meditating. The results of the study do not make clear whether meditation training creates this activity or if individuals with high gamma activity are attracted to meditation. (Antoine Lutz & Richard J. Davidson, 2004).

Meditation also affects brain wave production as measured by an EEG machine. While the brain at a waking state is primarily in the Beta range of frequencies (14 - 21 cycles per second), while under meditation the brain tends to slow down the Alpha range (7 - 14 cycles per second). One of the first Americans to study the effects of meditation on brainwave production was José Silva who founded the Silva Method. Silva theorized that meditation, in addition to stress relief, could also be used for enhancing creativity and developing intuition.

Adverse effects

Predominantly, studies of meditation report positive effects. However, some studies report that meditation may have adverse effects in certain circumstances (Lukoff, Lu & Turner, 1998; Perez-De-Albeniz & Holmes, 2000). If practiced improperly or too intensely, meditation can lead to considerable psychological and physiological problems, such as the symptoms of Kundalini syndrome, Shamanic illness, Tumo or Qi-gong-related problems . Serious, and credible teachers of meditation usually warn their students about the possible pitfalls of a contemplative path. Another issue concerns the adaptation of eastern meditative concepts to a western culture, an adaptation that is often unfamiliar with the cultural matrix that the meditative concept originated from. Eastern concepts of meditation are often imported to a western setting within the popular context of new religious movements, or within the context of popular approaches to body and health. It is common for this popular context to be unfamiliar with the broad range of adverse affects that might occur during meditation, and to have limited tools for dealing with them when they do arise.

Stories of unguided practitioners or inexpertly guided students developing chronic mental and physical health problems as a result of their attempts at meditation training are not uncommon. English speaking practitioners and teachers of Chinese Qigong and related disciplines note that the practice of this contemplative exercise is sometimes accompanied by physical and psychological distress. The identification of this syndrome has led to the inclusion of a culture-sensitive category in the DSM-IV called Qi-Gong Psychotic Reaction (American Psychiatric Association, 1994: Appendix 1).

Since the practice of meditation may include a powerful confrontation with existential questions, it is not considered wise to engage in intense meditation techniques without an extended period of psychological preparation, preferably in contact with a credible teacher or clinician. In the case of Asian contemplative traditions there often exist major challenges connected to the way the particular tradition is to be applied to a Western culture, or a Western mindset. A growing body of clinical literature is now starting to address the phenomenon of meditation-related problems (Lukoff, Lu & Turner, 1998; Perez-De-Albeniz & Holmes, 2000). Several side-effects have been reported, including uncomfortable kinaesthetic sensations, mild dissociation and psychosis-like symptoms (Craven, 1989). From a clinical study of twenty-seven long term meditators, Shapiro (1992) reported such adverse effects as depression, relaxation-induced anxiety and panic, paradoxical increases in tension, impaired reality testing, confusion, disorientation and feeling 'spaced out'. The possibility that meditation might trigger strong emotional reactions is also reported by Kutz, Borysenko & Benson (1985). Therefore, meditation might cause serious side effects, even among long-term practitioners, and might even, in some instances, be contraindicated (Perez-De-Albeniz & Holmes, 2000).

The tendency of meditation to disturb object-relations and release unconscious material implies that the beginning meditator should approach the practice with moderation. It usually takes years of dedication to become stable in a contemplative practice, a perspective that is often overlooked by many new religious movements and New Age therapies.

Meditative traditions which include the use of drugs are generally considered to be harmful to the practitioner. Additionally, as with any practice, meditation may also be used to avoid facing ongoing problems or emerging crises in the meditator's life. In such situations, it may be helpful to apply mindful attitudes acquired in meditation while actively engaging with current problems (see Hayes et al, 1999, chap. 3; Metzner, 2005).

Meditation and drugs

Some modern methods of meditation do not include the use of drugs due to the known health problems associated with drug use. However, the use of stimulants has been proposed by some as a means to provide insight, and in some shamanistic traditions they are used as agents of ritual. Some Native American traditions for instance emphasized the smoking of a pipe containing tobacco or other plants. Some Hindu traditions use bhang, East Asian traditions use tea and Middle Eastern (and many Western) religions use coffee as an aid to meditation. During the 1960s, eastern meditation traditions and LSD became popular among many people, and many people suggested that LSD use and meditation were both means to the same spiritual/existential end. However, many people who had already been familiar with eastern traditions rejected this idea, including many who had tried LSD themselves. In The Master Game, de Ropp said that the door to full consciousness could be glimpsed through with the aid of substances, yet to pass beyond the door required yoga and meditation.

See also

• Kinemantra Meditation
• Passage Meditation
• Mindfulness
• Vipassana
• Retreat
• Autosuggestion

References

• American Psychiatric Association. (1994). Diagnostic and Statistical Manual of Mental Disorders, fourth edition. Washington, D.C.: American Psychiatric Association.
• Austin, James H. (1999) Zen and the Brain: Toward an Understanding of Meditation and Consciousness, Cambridge: MIT Press, 1999, ISBN 0262511096
• Azeemi, Khwaja Shamsuddin (2005) Muraqaba: The Art and Science of Sufi Meditation. Houston: Plato, 2005, ISBN 0975887548
• Carlson LE, Ursuliak Z, Goodey E, Angen M, Speca M. (2001) The effects of a mindfulness meditation-based stress reduction program on mood and symptoms of stress in cancer outpatients: 6-month follow-up. Support Care Cancer. 2001 Mar;9(2):112-23.PubMed abstract PMID 11305069
• Craven JL. (1989) Meditation and psychotherapy. Canadian Journal of Psychiatry. Oct;34(7):648-53. PubMed abstract PMID 2680046
• Davidson RJ, Kabat-Zinn J, Schumacher J, Rosenkranz M, Muller D, Santorelli SF, Urbanowski F, Harrington A, Bonus K, Sheridan JF. (2003) Alterations in brain and immune function produced by mindfulness meditation. Psychosomatic Medicine 2003 Jul-Aug;65(4):564-70. PubMed abstract PMID 12883106
• Bennett-Goleman, T. (2001) Emotional Alchemy: How the Mind Can Heal the Heart, Harmony Books, ISBN 0-609-60752-9
• Hayes SC, Strosahl KD, Wilson KG. (1999) Acceptance and Commitment Therapy. New York: Guilford Press.
• Kabat-Zinn J, Lipworth L, Burney R. (1985) The clinical use of mindfulness meditation for the self-regulation of chronic pain. Journ. Behav. Medicine. Jun;8(2):163-90. PubMed abstract PMID 3897551
• Kutz I, Borysenko JZ, Benson H. (1985) Meditation and psychotherapy: a rationale for the integration of dynamic psychotherapy, the relaxation response, and mindfulness meditation. American Journal of Psychiatry, Jan;142(1):1-8. PubMed abstract PMID 3881049
• Lazar, Sara W.; Bush, George; Gollub, Randy L.; Fricchione, Gregory L.; Khalsa, Gurucharan; Benson, Herbert (2000) Functional brain mapping of the relaxation response and meditation [Autonomic Nervous System] NeuroReport: Volume 11(7) 15 May 2000 p 1581–1585 PubMed abstract PMID 10841380
• Lukoff, David; Lu Francis G. & Turner, Robert P. (1998) From Spiritual Emergency to Spiritual Problem: The Transpersonal Roots of the New DSM-IV Category. Journal of Humanistic Psychology, 38(2), 21-50,
• Metzner R. (2005) Psychedelic, Psychoactive and Addictive Drugs and States of Consciousness. In Mind-Altering Drugs: The Science of Subjective Experience, Chap. 2. Mitch Earlywine, ed. Oxford: Oxford University Press.
• Perez-De-Albeniz, Alberto & Holmes, Jeremy (2000) Meditation: Concepts, Effects And Uses In Therapy. International Journal of Psychotherapy, March 2000, Vol. 5 Issue 1, p49, 10p
• Peng CK, Mietus JE, Liu Y, Khalsa G, Douglas PS, Benson H, Goldberger AL. (1999) Exaggerated heart rate oscillations during two meditation techniques. Int J Cardiol. 1999 Jul 31;70(2):101–7. PubMed Abstract PMID 10454297
• Shalif, I. et al. (1985) Focusing on the Emotions of Daily Life (Tel-Aviv: Etext Archives, 1990)
• Shapiro DH Jr. (1992) Adverse effects of meditation: a preliminary investigation of long-term meditators. Int. Journal of Psychosom. 39(1-4):62-7. PubMed abstract PMID 1428622
• Venkatesh S, Raju TR, Shivani Y, Tompkins G, Meti BL. (1997) A study of structure of phenomenology of consciousness in meditative and non-meditative states. Indian J Physiol Pharmacol. 1997 Apr;41(2): 149–53. PubMed Abstract PMID 9142560
• Lutz, Antoine; Richard J. Davidson; et al (2004). "Long-term meditators self-induce high-amplitude gamma synchrony during mental practice". Proceedings of the National Academy of Sciences 101 (November 16). DOI:10.1073/pnas.0407401101.

External links

• Transcendental Meditation Program
• Mindfulness in plain English: nuts and bolts of meditation
• Article from time magazine "Scientists find that meditation not only reduces stress but also reshapes the brain".
• The McGovern Institute at MIT and The Mind & Life Institute present...Investigating the Mind
• MIT Technology review - Meditation and the Brain
• Harvard University Gazette - Meditation changes temperatures
• Harvard University News - His Holiness the XIVth Dalai Lama visits Harvard
• University Of Wisconsin News - The Dalai Lama and scientists unite to study meditation
• The Physical and Psychological Effects of Meditation (subtitle) A Review of Contemporary Research, Michael Murphy and Steven Donovan, Institute of Noetic Sciences, 1999-2004, full text of e-book with extensive searchable bibliography (type * into search box to retrieve entire list of over 1800 citations)
• General Introduction to Meditation - Covers basic styles and methods
• University of Oxford - Mindfulness-based Cognitive Therapy
• Harvard University Gazette - How not to get hooked
• Medical Observer - Making Sense of Meditation
• Buddhist Meditation
• Dovening on Hot Coals, a brief guide to Jewish meditation
• Meditation Overview A series of articles on guided meditation.
• Meditation associated with increased grey matter in the brain.
• Psychological State Changes in Meditation
• Dhammakaya Foundation
• pdf article on meditative aspects of traditional T'ai Chi Ch'uan
• Sufi Meditation
• What is Muraqaba
• MURAQABA
• Free/OpenSource meditation clock that runs on mobile devices
• The Buddhist Meditation - Dhyana
• Vipassana Meditation as taught by S.N. Goenka

Blood is a circulating tissue composed of fluid plasma and cells (red blood cells, white blood cells, platelets). Medical terms related to blood often begin in hemo- or hemato- (BE: haemo- and haemato-) from the Greek word "haima" for "blood".

The main function of blood is to supply nutrients (oxygen, glucose) and constitutional elements to tissues and to remove waste products (such as carbon dioxide and lactic acid). Blood also enables cells (leukocytes, abnormal tumor cells) and different substances (amino acids, lipids, hormones) to be transported between tissues and organs. Problems with blood composition or circulation can lead to downstream tissue dysfunction.

The blood is circulated around the lungs and body by the pumping action of the heart.

Contents 1 Anatomy of blood 2 Physiology of blood 2.1 Production and degradation 2.2 Transport of oxygen 2.2.1 Insects 2.2.2 Small invertebrates 2.3 Transport of carbon dioxide 2.4 Transport of hydrogen ions 2.5 Color 3 Health and disease 3.1 Ancient medicine 3.2 Diagnosis 3.3 Pathology 3.4 Treatment 4 Mythology and religion 4.1 Indo-European paganism 4.2 Judaism 4.3 Christianity 4.4 Jehovah's Witnesses 4.5 Vampire legends 4.6 Chinese and Japanese culture 5 See also

Anatomy of blood

Blood is composed of several kinds of corpuscles; these formed elements of the blood constitute about 45% of whole blood. The other 55% is blood plasma, a yellowish fluid that is the blood's liquid medium. The normal pH of human arterial blood is approximately 7.40 (normal range is 7.35-7.45). Blood that has a pH below 7.35 is acidic, while blood pH above 7.45 is alkaline. Blood pH along with paCO2 and HCO3 readings are helpful in determining the acid-base balance of the body. Blood is about 7% of the human body weight [1], so the average adult has a blood volume of about 5 liters, of which 2.7-3 liters is plasma. The combined surface area of all the erythrocytes in the human anatomy would be roughly 2,000 times as great as the body's exterior surface.

The corpuscles are:

• Red blood cells or erythrocytes (96%). In mammals, mature red blood cells lack a nucleus and organelles. They contain the blood's hemoglobin and distribute oxygen. The red blood cells (together with endothelial vessel cells and some other cells) are also marked by proteins that define different blood types.
• White blood cells or leukocytes (3.0%), are part of the immune system; they destroy infectious agents.
• Platelets or thrombocytes (1.0%) are responsible for blood clotting (coagulation)

Blood plasma is essentially an aqueous solution containing 96% water, 4% blood plasma proteins, and trace amounts of other materials. Some components are:

• albumin
• blood clotting factors
• immunoglobulins (antibodies)
• hormones
• various other proteins
• various electrolytes (mainly sodium and chlorine)

Together, plasma and corpuscles form a non-Newtonian fluid whose flow properties are uniquely adapted to the architecture of the blood vessels.

Physiology of blood

Production and degradation

Blood cells are produced in the bone marrow; the process is termed hematopoiesis. The proteinaceous component is produced overwhelmingly in the liver, while hormones are produced by the endocrine glands and the watery fraction maintained by the gut and the kidney.

Blood cells are degraded by the spleen and the Kupffer cells in the liver. The liver also clears proteins and amino acids (the kidney secretes many small proteins into the urine). Erythrocytes usually live up to 120 days before they are systematically replaced by new erythrocytes created by the process of hematopoiesis.

Transport of oxygen

Blood oxygenation is measured with the partial pressure of oxygen. 98.5% of the oxygen is chemically combined with the Hb. Only 1.5% is physically dissolved. The hemoglobin molecule is the primary transporter of oxygen in mammals and many other species.

With the exception of pulmonary and umbilical arteries and their corresponding veins, arteries carry oxygenated blood away from the heart and deliver it to the body via arterioles and capillaries, where the oxygen is consumed; afterwards, venules and veins carry deoxygenated blood back to the heart.

Under normal conditions in humans, hemoglobin in blood leaving the lungs is about 96-97% saturated with oxygen; 'deoxygenated' blood returning to the lungs is still approximately 75% saturated.[2][3] A fetus, receiving oxygen via the placenta, is exposed to much lower oxygen pressures (about 20% of the level found in an adult's lungs) and so fetuses produce another form of hemoglobin with a much higher affinity for oxygen (hemoglobin F) in order to extract as much oxygen as possible from this sparse supply.[4]

Insects

In insects, the blood (more properly called hemolymph) is not involved in the transport of oxygen. (Openings called tracheae allow oxygen from the air to diffuse directly to the tissues). Insect blood moves nutrients to the tissues and removes waste products.

Small invertebrates

In some small invertebrates like insects, oxygen is simply dissolved in the plasma. Larger animals use respiratory proteins to increase the oxygen carrying capacity. Hemoglobin is the most common respiratory protein found in nature. Hemocyanin (blue) contains copper and is found in crustaceans and mollusks. It is thought that tunicates (sea squirts) might use vanabins (proteins containing vanadium) for respiratory pigment (bright green, blue, or orange).

In many invertebrates, these oxygen-carrying proteins are freely soluble in the blood; in vertebrates they are contained in specialized red blood cells, allowing for a higher concentration of respiratory pigments without increasing viscosity or damaging blood filtering organs like the kidneys.

Transport of carbon dioxide

When systemic arterial blood flows through capillaries, carbon dioxide diffuses from the tissues into the blood. Some carbon dioxide is dissolved in the blood. Some carbon dioxide reacts with hemoglobin to form carbamino hemoglobin. The remaining carbon dioxide is converted to bicarbonate and hydrogen ions. Most carbon dioxide is transported through the blood in the form of bicarbonate ions.

Transport of hydrogen ions

Some oxyhemoglobin loses oxygen and becomes deoxyhemoglobin. Deoxyhemoglobin has a much greater affinity for H+ than does oxyhemoglobin so it binds most of the hydrogen ions.

Color

In humans and other hemoglobin-using creatures, oxygenated blood is a bright red in color. Deoxygenated blood is a darker shade of red, which can be seen during blood donation and when venous blood samples are taken. However, due to an optical effect caused by the way in which light penetrates through the skin, veins typically appear blue in color.[5] This has led to a common misconception that before venous blood is exposed to air it is blue.

Health and disease

Ancient medicine

Hippocratic medicine considered blood one of the four humors (together with phlegm, yellow bile and black bile). As many diseases were thought to be due to an excess of blood, bloodletting and leeching were a common intervention until the 19th century (it is still used for some rare blood disorders).

In classical Greek medicine, blood was associated with air, springtime, and with a merry and gluttonous (sanguine) personality. It was also believed to be produced exclusively by the liver.

Diagnosis

Blood pressure and blood tests are amongst the most commonly performed diagnostic investigations that directly concern the blood.

Pathology

See also blood diseases

Problems with blood circulation and composition play a role in many diseases.

• Wounds can cause major blood loss (see bleeding). The thrombocytes cause the blood to coagulate, blocking relatively minor wounds, but larger ones must be repaired at speed to prevent exsanguination. Damage to the internal organs can cause severe internal bleeding, or hemorrhage.
• Circulation blockage can also create many medical conditions from ischemia in the short term to tissue necrosis and gangrene in the long term.
• Hemophilia is a genetic illness that causes dysfunction in one of the blood's clotting mechanisms. This can allow otherwise inconsequential wounds to be life-threatening, but more commonly results in hemarthrosis, or bleeding into joint spaces, which can be crippling.
• Leukemia is a group of cancers of the blood-forming tissues.
• Major blood loss, whether traumatic or not (e.g. during surgery), as well as certain blood diseases like anemia and thalassemia, can require blood transfusion. Several countries have blood banks to fill the demand for transfusable blood. A person receiving a blood transfusion must have a blood type compatible with that of the donor.
• Blood is an important vector of infection. HIV, the virus which causes AIDS, is transmitted through contact between blood, semen, or the bodily secretions of an infected person. Hepatitis B and C are transmitted primarily through blood contact. Owing to blood-borne infections, bloodstained objects are treated as a biohazard.
• Infection of the blood is bacteremia or sepsis. Malaria and trypanosomiasis are blood-borne parasitic infections.

Treatment

Blood transfusion is the most direct therapeutic use of blood. It is obtained from human donors by blood donation. As there are different blood types, and transfusion of the incorrect blood may cause severe complications, crossmatching is done to ascertain the correct type is transfused.

Other blood products administered intravenously are platelets, blood plasma, cryoprecipitate and specific coagulation factor concentrates.

Many forms of medication (from antibiotics to chemotherapy) are administered intravenously, as they are not readily or adequately absorbed by the digestive tract.

As stated above, some diseases are still treated by removing blood from the circulation.

It is the fluid part of the blood that saves lives where severe blood loss occurs, other preparations can be given such as ringers atopical plasma volume expander as a non-blood alternative, and these alternatives where used are rivalling blood use where used.

Mythology and religion

Due to its importance to life, blood is associated with a large number of beliefs. One of the most basic is the use of blood as a symbol for family relationships; to be "related by blood" is to be related by ancestry or descendance, rather than marriage. This bears closely to bloodlines, and sayings such as "blood is thicker than water" and "bad blood", as well as "Blood brother".

Indo-European paganism

Among the Germanic tribes (such as the Anglo-Saxons and the Vikings), blood was used during the sacrifices, the Blóts. The blood was considered to have the power of its originator and after the butchering the blood was sprinkled on the walls, on the statues of the gods and on the participants themselves. This act of sprinkling blood was called bleodsian in Old English and the terminology was borrowed by the Roman Catholic Church becoming to bless and blessing. The Hittite word for blood, ishar was a cognate to words for "oath" and "bond", see Ishara.

Judaism

In Judaism, blood cannot be consumed even in the smallest quantity (Leviticus 3:17 and elsewhere); this is reflected in the dietary laws. Blood is purged from meat by salting and pickling.

Other rituals involving blood are the covering of the blood of fowl and game after slaughtering (Leviticus 17:13); the reason given by the Torah is: "Because the life of every animal is [in] his blood" (ibid 17:14), although from its context in Leviticus 3:17 it would appear that blood cannot be consumed because it is to be used in the sacrificial service (known as the korbanot), in the Temple in Jerusalem.

Ironically, Judaism has historically been the religion to be most affected by blood libels.

Christianity

Christians believe that the Eucharist wine is, or represents, the blood of Jesus. This belief is rooted in the Last Supper as written in the four gospels of the Bible, in which Jesus stated to his disciples that the bread which they ate represented his body, and the wine represented his blood. "This cup is the new testament in my blood, which is shed for you." (Luke 22:20, KJV). The accepted Christian belief is that Jesus' blood atoned for the sins of the people.

Jehovah's Witnesses

Main article: Jehovah's Witnesses and blood

Jehovah's Witnesses are prohibited from eating blood and accepting tranfusions of whole blood or any of red cells, white cells, platelets or plasma. They are permitted to accept fractions, and the acute normovolemic hemodilution (ANH) and autologous blood salvage (cell saver) procedures.

Vampire legends

Vampires are fictional beings thought to cheat death by drinking the blood of the living.

Chinese and Japanese culture

In Chinese culture, it is often said that if a man's nose produces a small flow of blood, this signifies that he is experiencing sexual desire. This often appears in Chinese-language and Hong Kong films. This is also evident in Japanese culture and is parodied in anime and manga. Male characters will often be shown with a nosebleed if they have just seen a female nude or in little clothing, or if they have had an erotic thought or fantasy.

See also

• Artificial blood
• List of human blood components
• Blood as food: see black pudding
• Blood and video game censorship
• Taboo food and drink
• Blood donation
• Blood types

Blood - Blood plasma - edit
Pluripotential hemopoietic stem cell | Red blood cells (Reticulocyte, Normoblast) | White blood cells
Lymphocytes (Lymphoblast)
T cells (Cytotoxic, Helper, Regulatory T cell) | B cells (Plasma cells & Memory B cells) | Natural killer cell
Myelocytes (Myeloblast)
Granulocytes (Neutrophil, Eosinophil, Basophil) | Mast cell precursors | Monocytes (Histiocyte, Macrophages, Dendritic cells, Langerhans cells, Microglia, Kupffer cells, Osteoclasts) | Megakaryoblast | Megakaryocyte | Platelets

Cardiovascular system - edit
Heart → Aorta → Arteries → Arterioles → Capillaries → Venules → Veins → Vena cava → Pulmonary arteries → Lungs → Pulmonary veins | Blood

Breathing transports oxygen into the body and carbon dioxide out of the body. Aerobic organisms require oxygen to create energy via respiration, in the form of energy-rich molecules such as glucose.

Humans typically breathe between 12 and 20 times per minute, with children breathing faster than adults. Babies may breathe as much as 40 times per minute. Adults normally breathe about 500-700ml of air at a time. An average 14 year old takes around 30,000 breaths per day.

Breath is sometimes used as a metaphor for life itself, and often "last breath" is the most obvious sign that death has occurred. The association between the end of life and breathing is not absolute, however. As modern treatment can now take over the process of breathing by mechanical ventilation, or CPR, breathing can be restarted if it stops. Because of this, in modern times death is now better defined in terms of brain function.

Breathing is only part of the process of delivering oxygen to where it is needed in the body. Breathing in, or inhaling, is usually an active movement, with the contraction of chest and diaphragm muscles needed. At rest, breathing out, or exhaling, is normally a passive process powered by the elastic recoil of the chest, similar to a deflating balloon. The process of gas exchange occurs in the alveoli by passive diffusion of gasses between the alveolar gas and the blood passing by in the lung capillaries. Once in the blood, the heart powers the flow dissolved gasses around the body in the circulation.

As well as carbon dioxide, breathing also results in loss of water from the body. Exhaled air has a relative humidity of 100% because of water diffusing across the moist surface of breathing passages and alveoli.

Control of breathing

Breathing is one of the few bodily functions which, within limits, can be controlled both consciously and unconsciously. Conscious attention to breathing is common in many forms of meditation, specifically anapana and other forms of yoga and Chinese qigong. In music, breath is used to play wind and brass musical instruments and many aerophones. Laughter, physically, is simply repeated sharp breaths. Hiccups are another still-mysterious breath-related phenomenon.

Specialized centers in the brainstem automatically regulate the rate and depth of breathing depending on the body’s needs at any time. When carbon dioxide levels increase in the blood, it reacts with the water in blood, producing carbonic acid. The drop in the blood's pH will then cause the medulla (signalling centre in brain) to send nerve impulses to the diaphragm and the intercostal muscles, increasing the rate of breathing. While exercising, the level of carbon dioxide in the blood increases due to increased cellular respiration by the muscles, and so breathing rate increases. During rest, the level of carbon dioxide is lower, so breathing rate is lower.This ensures an appropriate amount of oxygen is delivered to the muscles and other organs. This automatic control of respiration can be impaired in premature babies, or by drugs or disease.

It is not possible for a healthy person to voluntarily stop breathing. If we do not inhale, and the level of carbon dioxide builds up in our blood, and we experience overwhelming air hunger. This irrepressible reflex is not surprising given that without breathing the bodies internal oxygen levels drop dangerously low within minutes leading to permanent brain damage and then death.

Breathing is one of the few bodily functions which, within limits, can be controlled both consciously and unconsciously. Conscious attention to breathing is common in many forms of meditation, specifically anapana and other forms of yoga and Chinese qigong. In music, breath is used to play wind and brass musical instruments and many aerophones. Laughter, physically, is simply repeated sharp breaths. Hiccups are another still-mysterious breath-related phenomenon.

Specialized centers in the brainstem automatically regulate the rate and depth of breathing depending on the body’s needs at any time. When carbon dioxide levels increase in the blood, it reacts with the water in blood, producing carbonic acid. The drop in the blood's pH will then cause the medulla (signalling centre in brain) to send nerve impulses to the diaphragm and the intercostal muscles, increasing the rate of breathing. While exercising, the level of carbon dioxide in the blood increases due to increased cellular respiration by the muscles, and so breathing rate increases. During rest, the level of carbon dioxide is lower, so breathing rate is lower.This ensures an appropriate amount of oxygen is delivered to the muscles and other organs. This automatic control of respiration can be impaired in premature babies, or by drugs or disease.

See also

• Agonal breathing
• Cheyne-Stokes respiration
• Biot's respirationorder

Homeostasis is the property of an open system, especially living organisms, to regulate its internal environment to maintain a stable, constant condition, by means of multiple dynamic equilibrium adjustments, controlled by interrelated regulation mechanisms. The term was coined in 1932 by Walter Cannon from the Greek homo (same, like) and stasis (to stand, posture).

Contents 1 Overview 1.1 Properties of homeostasis 1.2 Mechanisms of homeostasis: feedback 2 Ecological homeostasis 3 Biological homeostasis 3.1 Homeostasis in the human body 4 Other fields 4.1 Examples 5 Cultural Referencecs 6 See also

Overview

The term is most often used in the sense of biological homeostasis. Multicellular organisms require a homeostatic internal environment, in order to live; many environmentalists believe this principle also applies to the external environment. Many ecological, biological, and social systems are homeostatic. They oppose change to maintain equilibrium. If the system does not succeed in reestablishing its balance, it may ultimately lead the system to stop functioning.

Complex systems, such as a human body, must have homeostasis to maintain stability and to survive. These systems do not only have to endure to survive; they must adapt themselves and evolve to modifications of the environment.

Properties of homeostasis

Homeostatic systems show several properties:

• They are ultrastable: the system is capable of testing which way its variables should be adjusted.
• Their whole organization (internal, structural, and functional) contributes to the maintenance of equilibrium.
• They are unpredictable: the resulting effect of a precise action often has the opposite effect to what was expected.

Main examples of homeostasis in mammals are as follows:

• The regulation of the amounts of water and minerals in the body. This is known as osmoregulation. This happens in the kidneys.
• The removal of metabolic waste. This is known as excretion. This is done by the excretory organs such as the kidneys and lungs.
• The regulation of body temperature. This is mainly done by the skin.
• The regulation of blood glucose level. This is mainly done by the liver and the insulin secreted by the pancreas.

It is important to note that while organisms exhibit equilibrium, their physiological state is not necessarily static. Many organisms exhibit endogenous fluctuations in the form of circadian (period 20 to 28 hours), ultradian (period <20 hours) and infradian (period > 28 hours) rhythms. Thus even in homeostasis, body temperature, blood pressure, heart rate and most metabolic indicators are not always at a constant level, but vary predictably over time.

Mechanisms of homeostasis: feedback

Main article: Feedback

When a change of variable occurs, there are two main types of feedback to which the system reacts:

• Negative feedback is a reaction in which the system responds in such a way as to reverse the direction of change. Since this tends to keep things constant, it allows the maintenance of homeostasis. For instance, when the concentration of carbon dioxide in the human body increases, the lungs are signaled to increase their activity and expel more carbon dioxide. Thermoregulation is another example of negative feedback. When body temperature rises (or falls), receptors in the skin and the hypothalamus sense a change, triggering a command from the brain. This command, in turn, effects the correct response, in this case a decrease in body temperature.

• In positive feedback, the response is to amplify the change in the variable. This has a destabilizing effect, so does not result in homeostasis. Positive feedback is less common in naturally occurring systems than negative feedback, but it has its applications. For example, in nerves, a threshold electric potential triggers the generation of a much larger action potential. (See also leverage points.) Blood clotting and events in childbirth are other types of positive feedback.

Sustainable systems require combinations of both kinds of feedback. Generally with the recognition of divergence from the homeostatic condition positive feedbacks are called into play, whereas once the homeostatic condition is approached, negative feedback is used for "fine tuning" responses. This creates a situation of "metastability", in which homeostatic conditions are maintained within fixed limits, but once these limits are exceeded, the system can shift wildly to a wholly new (and possibly less desirable) situation of homeostasis. Such catastrophic shifts may occur with increasing nutrient load in clear rivers suddenly producing a homestatic condition of high eutrophication and turbidity, for instance.

Ecological homeostasis

Ecological homeostasis is found in a climax community of maximum permitted biodiversity, given the prevailing ecological conditions.

In disturbed ecosystems or sub-climax biological communities such as the island of Krakatoa, after its major erruption in 1883, the established stable homeostasis of the previous forest climax ecosystem was destroyed and all life eliminated from the island. Krakatoa, in the years after the erruption went through a sequence of ecological changes in which successive groups of new plant or animal species followed one another, leading to increasing biodiversity and eventually culminating in a re-established climax community. This ecological succession on Krakatoa occurred in a number of sereal stages, in which a sere is defined as "a stage in a sequence of events by which succession occurs". The complete chain of seres leading to a climax is called a prisere. In the case of Krakatoa, the island as reached its climax community with eight hundred different species being recorded in 1983, one hundred years after the erruption which cleared all life off the island. Evidence confirms that this number has been homeostatic for some time, with the introduction of new species rapidly leading to elimination of old ones.

The evidence of Krakatoa, and other disturbed or virgin ecosystems shows that the initial colonisation by pioneer or R strategy species occurs through positive feedback reproduction strategies, where species are weeds, producing huge numbers of possible offspring, but investing little in the success of any one. Rapid boom and bust plague or pest cycles are observed with such species. As an ecosystem starts to approach climax these species get replaced by more sophisticated climax species which through negative feedback, adapt themselves to specific environmental conditions. These species, closely controlled by carrying capacity, follow K strategies where species produce fewer numbers of potential offspring, but invest more heavily in securing the reproductive success of each one to the microenvironmental conditions of its specific ecological niche.

It begins with a pioneer community and ends with a climax community. This climax community occurs when the ultimate vegetation has become in equilibrium with the local environment.

Such ecosystems form nested communities or heterarchies, in which homeostasis at one level, contributes to homeostatic processes at another holonic level. For example, the loss of leaves on a mature rainforest tree gives a space for new growth, and contributes to the leaf litter and soil humus build-up upon which such growth depends. Equally a mature rainforest tree reduces the sunlight falling on the forest floor and helps prevent invasion by other species. But trees too fall to the forest floor and a healthy forest glade is dependent upon a constant rate of forest regrowth, produced by the fall of logs, and the recycling of forest nutrients through the respiration of termites and other insect, fungal and bacterial decomposers. Similarly such forest glades contribute ecological services, such as the regulation of microclimates or of the hydrological cycle for an ecosystem, and a number of different ecosystems act together to maintain homeostasis perhaps of a number of river catchments within a bioregion. A diversity of bioregions similarly makes up a stable homeostatic biological region or biome.

In the Gaia hypothesis, James Lovelock stated that the entire mass of living matter on Earth (or any planet with life) functions as a vast homeostatic superorganism that actively modifies its planetary environment to produce the environmental conditions necessary for its own survival. In this view, the entire planet maintains homeostasis. Whether this sort of system is present on Earth is still open to debate. However, some relatively simple homeostatic mechanisms are generally accepted. For example, when atmospheric carbon dioxide levels rise, certain plants are able to grow better and thus act to remove more carbon dioxide from the atmosphere. When sunlight is plentiful and atmospheric temperature climbs, the phytoplankton of the ocean surface waters thrive and produce more dimethyl sulfide, DMS. The DMS molecules act as cloud condensation nuclei which produce more clouds and thus increase the atmospheric albedo and this feedsback to lower the temperature of the atmosphere. As scientists discover more about Gaia, vast numbers of positive and negative feedback loops are being discovered, that together maintain a metastable condition, sometimes within very broad range of environmental conditions.

Biological homeostasis

Homeostasis is one of the fundamental characteristics of living things. It is the maintenance of the internal environment within tolerable limits.

The internal environment of a living organism's body features body fluids in multicellular animals. The body fluids include blood plasma, tissue fluid and intracellular fluid. The maintenance of a steady state in these fluids is essential to living things as the lack of it harms the genetic material.

With regard to any parameter, an organism may be a conformer or a regulator. Regulators try to maintain the parameter at a constant level, regardless of what is happening in its environment. Conformers allow the environment to determine the parameter. For instance, endothermic animals maintain a constant body temperature, while ectothermic animals exhibit wide variation in body temperature.

This is not to say that conformers may not have behavioral adaptations that allow them to exert some control over the parameter in question. For instance, reptiles often sit on sun-heated rocks in the morning to raise their body temperatures.

An advantage of homeostatic regulation is that it allows the organism to function more effectively. For instance, ectotherms tend to become sluggish at low temperatures, whereas endotherms are as active as always. On the other hand, regulation requires energy. One reason snakes are able to eat just once a week is that they use much less energy for maintaining homeostasis.

Homeostasis in the human body

All sorts of factors affect the suitability of the human body fluids to sustain life; these include properties like temperature, salinity, and acidity, and the concentrations of nutrients such as glucose, various ions, oxygen, and wastes, such as carbon dioxide and urea. Since these properties affect the chemical reactions that keep bodies alive, there are built-in physiological mechanisms to maintain them at desirable levels.

Homeostasis is not the reason for these ongoing unconscious adjustments. It should be thought of as a general characterization of many normal processes in concert, not their proximal cause. Moreover, there are numerous biological phenomena which do not conform to this model, such as anabolism.

Other fields

The term has come to be used in other fields, as well.

An actuary may refer to risk homeostasis, where (for example) people who have anti-lock brakes have no better safety record than those without anti-lock brakes, because they unconsciously compensate for the safer vehicle via less-safe driving habits. Previously certain manoeuvres involved minor skids, evoking fear and avoidance: now the anti-lock system moves the boundary for such feedback and behaviour patterns expand into the no-longer punitive area.

Sociologists and psychologists may refer to stress homeostasis, the tendency of a population or an individual to stay at a certain level of stress, often generating artificial stresses if the "natural" level of stress is not enough.

Examples

• Thermoregulation
  • The skeletal muscles can shiver to produce heat if the body temperature is too low.
  • Non-shivering thermogenesis involves the decomposition of fat to produce heat.
  • Sweating cools the body with the use of evaporation.
• Chemical regulation
  • The pancreas produces insulin and glucagon to control blood-sugar concentration.
  • The lungs take in oxygen and give off carbon dioxide.
  • The kidneys remove urea, and adjust the concentrations of water and a wide variety of ions.

Most of these organs are controlled by hormones secreted from the pituitary gland, which in turn is directed by the hypothalamus.

Cultural Referencecs

Ecological homeostasis is a major plot element in the 1996 Pauly Shore film Bio-Dome.

See also

• Acclimatization
• Biological rhythm
• Metabolism
• Apoptosis
• Aging
• Balance
• Osmosis
• Self-organization
• Cybernetics

Edit	General subfields and scientists in Cybernetics
K1	Polycontexturality, Second-order cybernetics
K2	Catastrophe theory, Connectionism, Control theory, Decision theory, Information theory, Semiotics, Synergetics, Sociosynergetics, Systems theory
K3	Biological cybernetics, Biomedical cybernetics, Biorobotics, Computational neuroscience, Homeostasis, Medical cybernetics, Neuro cybernetics, Sociocybernetics
Cyberneticians	William Ross Ashby, Claude Bernard, Valentin Braitenberg, Ludwig von Bertalanffy, George S. Chandy, Joseph J. DiStefano III, Heinz von Foerster, Charles François, Jay Forrester, Buckminster Fuller, Ernst von Glasersfeld, Francis Heylighen, Erich von Holst, Stuart Kauffman, Sergei P. Kurdyumov, Niklas Luhmann, Warren McCulloch, Humberto Maturana, Horst Mittelstaedt, Talcott Parsons, Walter Pitts, Alfred Radcliffe-Brown, Robert Trappl, Valentin Turchin, Francisco Varela, Frederic Vester, John N. Warfield, Kevin Warwick, Norbert Wiener

Traditional Chinese medicine (TCM) also known simply as Chinese medicine (Chinese: 中醫, zhōngyī xué, or 中藥學, zhōngyaò xué) is the name commonly given to a range of traditional medical practices used in China that have developed over the course of several thousand years of history. It is also regarded as an instance of oriental medicine, a term which may include other traditional Asian medical systems such as Japanese, Korean, Tibetan, and Mongolian medicine. Chinese medicine principally employs a method of analysis and synthesis, inquiring on a macro-level into the internal systems of the human body and their mutual relationships with the internal and external environment in an attempt to gain an understanding of the fundamental laws which govern the functioning of the human organism, and to apply this understanding to the treatment and prevention of disease, and health maintenance. TCM is rooted in a unique, comprehensive and systematic theoretical structure which includes the Theory of the Five Elements, the human body Meridian system, Yin-yang and other systems. Treatment is conducted with reference to this philosophical framework.

Contents 1 Uses 2 TCM theory 3 TCM diagnostics 3.1 Diagnostic techniques 4 TCM treatment techniques 5 TCM and science 5.1 The question of efficacy 5.2 Purported mechanism of action 5.3 Safety of Chinese medicines 6 The relationship between TCM and Western medicine 7 TCM and Animals 8 See also 9 References 10 External links

Uses

In the West, TCM is often considered alternative medicine; however, in mainland China and Taiwan, TCM is widely considered to be an integral part of the health care system. The term TCM is sometimes used specifically within the field of Chinese medicine to refer to the standardized set of theories and practices introduced in the mid-20th century under the government of Mao, as distinguished from related traditional theories and practices preserved by people in Taiwan, Hong Kong and by the overseas Chinese. The more general sense is meant in this article.

TCM developed as a form of noninvasive therapeutic intervention (also described as folk medicine or traditional medicine) rooted in ancient belief systems, including traditional religious concepts. Chinese medical practitioners before the 19th century relied on observation, trial and error, which incorporated certain mystical concepts. Like their Western counterparts, doctors of TCM had a limited understanding of infection, which predated the discovery of bacteria, viruses (germ theory of disease) and an understanding of cellular structures and organic chemistry. Instead they relyed mainly on observation and description on the nature of infections for creating remedies. Based on theories formulated through three millennia of observation and practical experience, a system of procedure was formed as to guide a TCM practitioner in courses of treatment and diagnosis.

Unlike other forms of traditional medicine which have largely become extinct, traditional Chinese medicine continues as a distinct branch of modern medical practice, and within China, it is an important part of the public health care system. There are thousands of years of empirical knowledge about TCM conceptualized and recorded in terms appropriate to that system, and in recent decades there has been an effort to integrate the discoveries made by traditional Chinese medicine with the discoveries made by workers in the Western medical traditions. One important component of this work is to use the instrumentation and the methodological tools available via Western medicine to investigate observations made and hypotheses raised by the Chinese tradition.

That this effort has occurred is surprising to many for a number of reasons. In most of the world, indigenous medical practices have been supplanted by practices brought from the West, while in Chinese societies, this has not occurred and shows no sign of occurring. Furthermore, many have found it peculiar that Chinese medicine remains a distinct branch of medicine separate from Western medicine, while the same has not happened with other intellectual fields. There is, for example, no longer a distinct branch of Chinese physics or Chinese biology.

TCM is used by some to treat the side effects of chemotherapy, treating the cravings and withdrawal symptoms of drug addicts and treating a variety of chronic conditions that conventional medicine is claimed to be sometimes ineffective in treating. TCM has also been used to treat antibiotic-resistant infection

A report issued by the Victorian state government in Australia states that:

Graduates from TCM university courses are able to diagnose in western medical terms, prescribe western pharmaceuticals, and undertake minor surgical procedures. In effect, they practise TCM as a specialty within the broader organisation of Chinese health care. [1]

TCM theory

There are many schools of thought on which TCM is based. Because of this, the foundation principles of Chinese medicine are not necessarily uniform. Received TCM can be shown to be most influenced by Taoism, Buddhism, and Neo-Confucianism.

For over 3000 years (1200 BC - present), Chinese academics of various schools have focused on the observable natural laws of the universe and their implications for the practical characterisation of humanity's place in the universe. In the I Ching and other Chinese literary and philosophical classics, they have described some general principles and their applications to health and healing:

• There are observable principles of constant phenomenal change by which the Universe is maintained.
  • Man is part of the universe and cannot be separated from the universal process of change.
• As a result of these apparently inescapable primordial principles, the Universe (and every process therein) tends to eventually balance itself.
  • Optimum health should result from living as harmoniously as possible with the spontaneous process of change tending towards balance. If there is no change (stagnation), or too much change (catastrophism), balance is increasingly lost and illnesses can occur.
• Everything is ultimately interconnected.
  • Always use a systemic approach when addressing imbalances.

TCM is therefore largely based on the philosophical concept that the human body is a small universe with a set of complete and sophisticated interconnected systems. Those systems usually work in balance to maintain the healthy function of the human body. The balance is described as necessarily including qi, blood, jing, bodily fluids, the wu xing, emotions, and spirit (shen). TCM has a unique model of the body, notably concerned with the meridian system. TCM isn't monolithic, however, and there are from minor to significant regional and philosophical differences between practitioners and schools which in turn can lead to differences in practice and theory.

TCM diagnostics

The basics of TCM diagnostics are: observe (望 wàng), hear and smell (聞 wén), ask about background (問 wèn) and read the pulse (切 qiè). Then a diagnosis is made using a system to classify the symptoms.

Systems of diagnosis include:

• Yin or Yang
• Five elements
• eight principles
• Zang Fu theory
• Meridian (Chinese medicine)
• Six levels
• four stages
• Three jiaos

And a modern cross that is not formal but in China TCM diagnosis is being very heavily influenced by and integrated with western diagnostic thought moving towards total integration of the two systems. Modern practitioners often use the systems in combination to understand what is happening with the patient.

Because traditional Chinese medicine predates the more invasive medical testing used in conventional Western medicine, TCM requires skill in a range of diagnostic systems not commonly used outside of TCM. Much of this diagnostic skill involves developing the abilities to observe subtle appearances; to observe that which is right in front of us, but escapes the observation of most people.

Diagnostic techniques

• Palpation of the patient's radial artery pulse in six positions
• Observation of the appearance of the patient's tongue
• Observation of the patient's face
• Palpation of the patient's body (especially the abdomen) for tenderness
• Observation of the sound of the patient's voice
• Observation of the surface of the ear
• Observation of the vein on the index finger on small children
• Comparisons of the relative warmth or coolness of different parts of the body
• Anything else that can be observed without instruments and without harming the patient

TCM treatment techniques

The traditional treatment in Chinese medicine consists of six major methods:

1. Tui na(推拿)
2. Acupuncture(針疚)
3. Acupoint therapy
4. Moxibustion(艾炙)
5. Cupping(拔罐)
6. Herbology(中药)
7. Physical culture related to breathing and circulation exercises like qigong (氣功) or T'ai Chi Ch'uan (太極拳) and other Chinese martial arts. Die-da or Tieh Ta (跌打): practitioners who specialize in healing trauma injury such as bone fractures, sprains, bruises etc. Some of these specialists may also use or recommend other disciplines of Chinese medical therapies (or Western medicine in modern times) if serious injury is involved. These practices are also seen as health maintenance regimes as well as interventions.

Traditional Chinese medicine uses herbs and other drugs as the last resort to fight health problems. This conforms to its basic belief: a human body has a sophisticated system to find illness, allocate resources and energy and heal the problems by itself. The goal of external efforts should carefully focus on assisting the normal self-healing function of human body, not interfering with it. There is a Chinese saying which reflects the same idea: "Any medicine has 30% poison ingredients."

The modern practice of traditional Chinese medicine is increasingly incorporating techniques and theories of Western medicine in its praxis.

Other specialties include:

• Nutrition or food therapy
• Gua Sha or coin-rubbing (刮痧)
• Auriculotherapy(耳燭療法)

TCM and science

The question of efficacy

Most scientific research in the West about TCM has focused on acupuncture. The National Institutes of Health Consensus Statement on Acupuncture summarizes research on the efficacy of acupuncture as follows:

...promising results have emerged, for example, efficacy of acupuncture in adult post-operative and chemotherapy nausea and vomiting and in postoperative dental pain. There are other situations such as addiction, stroke rehabilitation, headache, menstrual cramps, tennis elbow, fibromyalgia, myofascial pain, osteoarthritis, low back pain, carpal tunnel syndrome, and asthma for which acupuncture may be useful as an adjunct treatment or an acceptable alternative or be included in a comprehensive management program. Further research is likely to uncover additional areas where acupuncture interventions will be useful.

Much less work in the West has been done on Chinese herbal medicines, which comprises much of TCM in China. It is clear, however, that many if not most of these medicines do have powerful biochemical effects. An example is the herb ephedra which was introduced into the West as a stimulant, and later banned in the United States after deaths were attributed to its use. A less controversial example is artemisinin, derived from a herb long-used used in TCM, and now used worldwide to treat multi-drug resistant strains of falciparum malaria. In the West, many Chinese medicines have been marketed as herbal supplements and there has been considerable controversy over the regulatory status of these substances.

TCM practitioners have no philosophical objections to scientific studies on the effectiveness of treatments. The main barrier to the adoption of Chinese herbal medicines into Western practice is economic. It requires a large amount of expertise and money to conduct, for example, a double-blind drug trial, making it a large venture to test even one of the thousands of compounds used by TCM. Because these compounds cannot be patented and owned exclusively, there is a distinct disincentive to sponsor such expensive protocols. Some important western medical drugs have come from Chinese herbs like Ephedrine.

There are also great a priori doubts about the efficacy of many TCM treatments that appear to have their basis in magical thinking, e.g. plants with heart-shaped leaves will help the heart, ground bones of tiger give a person energy because tigers are energetic animals and so on. To researchers, this is a very small base to start serious research on.

Purported mechanism of action

The basic mechanism of TCM is akin to treating the body as a black box, recording and classifying changes and observations of the patient using a traditional philosophy. In contrast to many alternative and complementary medicines such as homeopathy, practically all techniques of TCM have explanations for why they may be more effective than a placebo, which Western medicine can find plausible. Most doctors of Western medicine would not find implausible claims that qigong preserves health by encouraging relaxation and movement, that acupuncture relieves pain by stimulating the production of neurotransmitters, or that Chinese herbal medicines may contain powerful biochemical agents. However, the causative mechanisms of healing often traditionally claimed to be at work in TCM techniques such as "manipulation of qi" as in the case of qigong and accupuncture, are often not recognized as scientifically valid or even possible.

Safety of Chinese medicines

Accupressure and accupuncture are largely accepted to be safe from results gain through medical studies. However, there is always the possiblity of nerve damage or infection in the latter treatment if the practitioner are not experienced or does not follow sanitation guidelines.

Chinese herbal medicines, in certain cases, involve risk of poisoning or allergic reactions. Cases of acute and chronic poisoning due to treatment through ingested Chinese medicines are relatively common in China, Hong Kong, and Taiwan, with numerous deaths occurring each year. For example, the Chinese herb má huáng — known commonly in the west by its Latin name Ephedra — is currently banned by the FDA. Although an effective bronchial dilator for the treatment of asthma in some cases, its active constituent ephedrine has an elevating effect on heart rate and blood pressure and has been linked to deaths. Although some of these cases can be attributed to practitioners who participate in quackery or people who self-medicate, poisonings are also caused by certified herbalists and doctors of Chinese medicine.

Furthermore, potentially toxic and carcinogenic compounds such as arsenic and cinnabar are sometimes prescribed as part of a medicinal mixture or used on the basis of "using poison to cure poison". Unprocessed herbals are sometimes adulterated with chemicals that may alter the intended effect of a herbal preparation or prescription. Much of these can be prevented with more empirical studies of Chinese herbals and tighter regulation regarding the growing, processing, and prescription of various herbals.

The relationship between TCM and Western medicine

Within China, there has been a great deal of cooperation between TCM practitioners and Western medicine, especially in the field of ethnomedicine. Chinese herbal medicine includes many compounds which are unused by Western medicine, and there is great interest in those compounds as well as the theories which TCM practitioners use to determine which compound to prescribe. For their part, advanced TCM practitioners in China are interested in statistical and experimental techniques which can better distinguish medicines that work from those that do not. One result of this collaboration has been the creation of peer reviewed scientific journals and medical databases on traditional Chinese medicine.

The relationship between TCM and Western medicine in the West is more contentious. While more and more medical schools are including classes on alternative medicine in their curricula, older Western doctors and scientists are far more likely than their Chinese counterparts to skeptically view TCM as archaic pseudoscience and superstition. This skepticism can come from a number of sources. For one, TCM in the West tends to be advocated either by Chinese immigrants or by those that have lost faith in conventional medicine. Many people in the West have a stereotype of the East as mystical and unscientific, which attracts those in the West who have lost hope in science and repels those who believe in scientific explanations. There have also been experiences in the West with unscrupulous or well-meaning but improperly-trained "TCM practitioners" who have done people more harm than good in many instances.

As an example of the different roles of TCM in China and the West, a person with a broken bone in the West (i.e. a routine, "straightforward" condition) would almost never see a Chinese medicine practitioner or visit a martial arts school to get the bone set, whereas this is routine in China. As another example, most TCM hospitals in China have electron microscopes and many TCM practitioners know how to use one.

This is not to say that TCM techniques are considered worthless in the West. In fact, Western pharmaceutical companies have recognized the value of traditional medicines and are employing teams of scientists in many parts of the world to gather knowledge from traditional healers and medical practitioners. After all, the active ingredients of most modern medicines were discovered in plants or animals. The particular contribution of Western medicine is that it strictly applies the scientific method to promising traditional treatments, separating those that work from those that do not. As another example, most Western hospitals and increasing numbers of other clinics now offer T'ai Chi Ch'uan or qigong classes as part of their inpatient and community health programs.

Most Chinese in China do not see traditional Chinese medicine and Western medicine as being in conflict. In cases of emergency and crisis situations, there is generally no reluctance in using conventional Western medicine. At the same time, belief in Chinese medicine remains strong in the area of maintaining health. To put it simply, you see a Western doctor if you have acute appendicitis, but you do exercises or take Chinese herbs to keep your body healthy enough to prevent appendicitis, or to recover more quickly from the surgery. Very few practitioners of Western medicine in China reject traditional Chinese medicine, and most doctors in China will use some elements of Chinese medicine in their own practice.

A degree of integration between Chinese and Western medicine also exists in China. For instance, at the Shanghai cancer hospital, a patient may be seen by a multidisciplinary team and be treated concurrently with radiation surgery, Western drugs and a traditional herbal formula.

It is worth noting that the practice of Western medicine in China is somewhat different from that in the West. In contrast to the West, there are relatively few allied health professionals to perform routine medical procedures or to undertake procedures such as massage or physical therapy.

In addition, Chinese practitioners of Western medicine have been less impacted by trends in the West that encourage patient empowerment, to see the patient as an individual rather than a collection of parts, and to do nothing when medically appropriate. Chinese practitioners of Western medicine have been widely criticized for overprescribing drugs such as corticosteroids or antibiotics for common viral infections. It is likely that these medicines, which are generally known to be useless against viral infections, would provide less relief to the patient than traditional Chinese herbal remedies.

TCM and Animals

As animal products are used in Chinese formulas, vegans and vegetarians should inform their practitioner, if their beliefs forbid the ingestion of animals. Often alternative substances can be used.

The use of endangered species is controversial within TCM. In particular, the belief that tiger penis and rhinoceros horn are aphrodisiacs has been blamed for depleting these species in the wild. Medicinal use is also having a major impact on the populations of sea horses.

The animal rights movement notes that a few traditional Chinese medicinal solutions use bear bile. To extract maximum amounts of the bile, the bears are often fitted with a sort of permanent catheter. The treatment itself and especially the extraction of the bile is very painful, causes damage to the intestines of the bear, and often even kills the bears. However, due to international attention on the issues surrounding its harvesting, bile is now rarely used by practitioners outside of China.

See also

• History of traditional Chinese medicine
• Public health in the People's Republic of China
• Traditional Japanese medicine (Kampo)
• Traditional Korean medicine

References

• Chang, Stephen T. The Great Tao; Tao Longevity; ISBN 0942196015 Stephen T. Chang
• Kaptchuck, Ted J., The Web That Has No Weaver; Congdon & Weed; ISBN 0809229331Z
• Maciocia, Giovanni, The Foundations of Chinese Medicine: A Comprehensive Text for Acupuncturists and Herbalists; Churchill Livingstone; ISBN 0443-039801
• Ni, Mao-Shing, The Yellow Emperor's Classic of Medicine : A New Translation of the Neijing Suwen with Commentary; Shambhala, 1995; ISBN 1570620806
• Holland, Alex Voices of Qi: An Introductory Guide to Traditional Chinese Medicine; North Atlantic Books, 2000; ISBN 1556433263
• Unschuld, Paul U., Medicine in China: A History of Ideas; University of California Press, 1985; ISBN 0520050231
• Qu, Jiecheng, When Chinese Medicine Meets Western Medicine - History and Ideas (in Chinese); Joint Publishing (H.K.), 2004; ISBN 9620423364
• Chan, T.Y. (2002). Incidence of herb-induced aconitine poisoning in Hong Kong: impact of publicity measures to promote awareness among the herbalists and the public. Drug Saf. 25:823–828.
• Benowitz, Neal L. (2000) Review of adverse reaction reports involving ephedrine-containing herbal products. Submitted to U.S. Food and Drug Administration. Jan. 17.

External links

• State Administration of Traditional Chinese Medicine for the People's Republic of China
• State Administration of Traditional Chinese Medicine for the People's Republic of China (English)
• Acumedic - The Comprehensive Organisation for Acupuncture, Chinese and Herbal Medicine
• Journal of Chinese Medicine
• General information about Chinese Medicine
• Classics of Traditional Chinese Medicine, by the National Library of Medicine (NLM)
• Modern Medicine and Traditional Chinese Medicine - Diabetes
• Acupuncture. NIH Consensus Statement 1997 Nov 3-5; 15(5):1-34.
• China, Chi, and Chicanery (a sceptical view)
• Effects of acupuncture on gastroparesis study
• Traditional Chinese Medicine--A Favored Adjunctive Therapy for American Cancer Patients
• Merging Chinese Traditional Medicine into the American Health System
• The Chinese Medicine Sampler- Historical Roots of Traditional Chinese Medicine
• A Visit to a Chinese Pharmacy, a virtual tour
• Chinese medicine, Chinese Herbal Medicine and Acupuncture Medline Most recent research articles on Chinese medicine, Chinese Herbal Medicine and Acupuncture from Medline/Entrez PubMed
• A selection of best-selling books on Traditional Chinese Medicine By well known author and chinese health and healing expert, Daniel Reid

Yin	Yang
moon	sun
night	day
dark	light
cool	warm
rest	active
feminine	masculine
north	south
winter	summer
right	left
introversion	extroversion
earth	heaven
even	odd
6*	9*
8**	7**
* major symbol numbers; ** minor symbol numbers

The concept of yin and yang (Traditional Chinese: 陰陽; Simplified Chinese: 阴阳; Pinyin: yīnyáng; Korean hangul: 음양; hanja: 陰陽; revised: eumyang; McCune-Reischauer: ŭmyang; Vietnamese: Âm-Dương) originates in ancient Chinese philosophy and metaphysics, which describes two primal opposing but complementary forces found in all things in the universe. Yin, the darker element, is passive, dark, feminine, downward-seeking, and corresponds to the night; yang, the brighter element, is active, light, masculine, upward-seeking and corresponds to the day. Yin is often symbolized by water, while yang is symbolized by fire.

The pair probably goes back to ancient agrarian religion; it exists in Confucianism, and it is prominent in Taoism. Though the words yin and yang only appear once in the Tao Te Ching, the book is laden with examples and clarifications of the concept of mutual arising.

Yin and yang are descriptions of complementary opposites rather than absolutes. Any yin/yang dichotomy can be seen as its opposite when viewed from another perspective. The categorisation is seen as one of convenience. Most forces in nature can be broken down into their respective yin and yang states, and the two are usually in movement rather than held in absolute stasis.

The symbol can also be written as ☯, with unicode 0x262f.

Contents 1 Meaning of terms 2 Principles 3 Notes 4 See Also 5 External links

Meaning of terms

The meaning of the characters for yin and yang, necessarily, has more than just one connotation. Because yang means "sunny", it corresponds to the day and more active functions, whereas yin, meaning "shady", corresponds to night and dormancy. Yin and yang can be compared in the chart to the right.

It is also possible to look at yin and yang with respect to the flow of time. Noon, is full yang, sunset is yang turning to yin; midnight is full yin and sunrise is yin turning to yang. This flow of time can also be expressed in seasonal changes and directions. South and summer are full yang; west and autumn are yang turning to yin; north and winter are full yin, and east and spring are yin turning over to yang.

Yin and yang is often used in reference to disease, and many Asian cultures treat the hot/cold or wet/dry diseases with opposite treatments. For example, a yin symptom such as coldness would be treated with yang treatments, such as hot foods. A yang symptom such as nervousness would be treated with yin treatments--cold foods such as fruits.

Yin and yang can also be seen as a process of transformation which describes the changes between the phases of a cycle. For example, cold water (yin) can be boiled and eventually turn into steam (yang).

One way to write the symbols for yin and yang are a solid line (yang) and a broken line (yin) which could be divided into the four stages of yin and yang and further divided into the eight trigrams (these trigrams are used on the South Korean flag). The symbol shown at the top righthand corner of this page, called Taijitu (太極圖), is another way to show yin and yang. The mostly white portion, being brighter, is yang and the mostly dark portion, being dim, is yin. Each, however, contains the seed of its opposite. Yin and yang are equally important, unlike the typical dualism of good and evil.

The concept is called yin yang, not yang yin, just because the former has a preferred pronunciation in Chinese (see Standard Mandarin - Tones for detail), and the word order has no cultural or philosophical meaning.

Principles

Everything can be described as either yin or yang.

1. Yin and yang are opposites.

Everything has its opposite—although this is never absolute, only comparative. No one thing is completely yin or completely yang. Each contains the seed of its opposite. For example, winter can turn into summer; "what goes up must come down".

2. Yin and yang are interdependent.

One cannot exist without the other. For example, day cannot exist without night.

3. Yin and yang can be further subdivided into yin and yang.

Any yin or yang aspect can be further subdivided into yin and yang. For example, temperature can be seen as either hot or cold. However, hot can be further divided into warm or burning; cold into cool or icy. Within each spectrum, there is a smaller spectrum; every beginning is a moment in time, and has a beginning and end, just as every hour has a beginning and end.

4. Yin and yang consume and support each other.

Yin and yang are usually held in balance—as one increases, the other decreases. However, imbalances can occur. There are four possible imbalances: Excess yin, excess yang, yin deficiency, and yang deficiency. They can again be seen as a pair: by excess of yin there is yang deficiency and vice versa. The imbalance is also a relative factor: the excess of yang "forces" yin to be more "concentrated".

5. Yin and yang can transform into one another.

At a particular stage, yin can transform into yang and vice versa. For example, night changes into day; warmth cools; life changes to death. However this transformation is relative too. Night and day coexist on Earth at the same time when shown from space.

6. Part of yin is in yang and part of yang is in yin.

The dots in each serve: 1. as a reminder that there are always traces of one in the other. For example, there is always light within the dark (e.g., the stars at night), these qualities are never completely one or the other. 2. as a reminder that absolute extreme side transforms instantly into the opposite, or that the labels yin and yang are conditioned by an observer's point of view. For example, the hardest stone is easiest to break. This can show that absolute discrimination between the two is artificial.

Notes

- Yin and Yang have also appeared as characters in various stories, representing the direct opposites and complementary nature of the two characters.

- Yin and Yang, in Otogi 2:Immortal Warriors, were two Guardians from the Land of the Dead that blocked the passage to the Land of the Living.

See Also

• Chinese mythology
• Chinese philosophy
• Metaphysics
• Agrarian
• Confucianism
• Taoism
• Tao Te Ching

External links

• Yin-yang symbol defined and illustrated
• Online course on the philosophy of yin-yang from the Way of Perfect Emptiness
• Yin and Yang Yin and Yang information page translated from historic text.

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Pushing hands, (推手, Wade-Giles t'ui¹ shou³, pinyin tuī shǒu), is a name for two-person training routines practiced in internal Chinese martial arts such as Pa Kua Chang (Baguazhang), Hsing-i Ch'uan (Xingyiquan), T'ai Chi Ch'uan (Taijiquan) and I Ch'uan (Yiquan).

Contents 1 Overview 2 History 3 Training pushing hands 3.1 See also

Overview

Pushing hands is said to be the gateway for students to understand experientially the martial art aspects of the nei chia (內家 nèi jiā or internal style) martial arts; leverage, reflex, sensitivity, timing, coordination and positioning. The theory being that there is a limit to the amount of physical conditioning available from performing solo form routines, so pushing hands adds the weight of the training partner's pushes onto the legs of the student, legs already bearing the student's own weight. The student then has to deal with the extra work load effectively from a martial point of view before returning their own pushes to the partner in turn. In that sense pushing hands is a contract between students to train the defensive and offensive movement principles of their martial art; learning to generate, coordinate and deliver power to another and also how to effectively neutralize incoming forces in a relatively safe environment.

History

Pushing hands is said by T'ai Chi's Chen family to have been be created by Chen Wangting (1600-1680) the founder of the Chen style Tai Chi Chuan and was originally known as hitting hands (da shou) or crossing hands (ke shou). Chen was said to have devised pushing hands methods for both empty hands and armed with spears. Other T'ai Chi schools attribute the invention of pushing hands to Zhang Sanfeng.

Training pushing hands

In T'ai Chi Ch'üan, pushing hands is used to acquaint students with the principles of what are known as the "Eight Gates and Five Steps," eight different leverage applications in the arms accompanied by footwork in a range of motion which proponents say will eventually allow students to defend themselves calmly and competently if attacked.

The Eight Gates (八門 bā mén):

P'eng (掤, py péng) - An upward circular movement, forward or backward, yielding or offsetting usually with the arms to disrupt the opponent's centre of gravity, often translated as "Ward Off."

Lü (履, lǜ) - A sideways, circular yielding movement, often translated as "Roll Back."

Chi (擠, jǐ) - A pressing or squeezing offset in a direction away from the body, usually done with the back of the hand or outside edge of the forearm. Chi is often translated as "Press."

An (按, àn) - To offset with the hand, usually a slight lift up with the fingers then a push down with the palm, which can appear as a strike if done quickly. Often translated as "Push."

Tsai (採, cǎi) - To pluck or pick downwards with the hand, especially with the fingertips or palm. The word tsai is part of the compound that means to gather, collect or pluck a tea leaf from a branch (採茶, cǎi chá). Often translated "Pluck."

Lieh (挒, liè) - Lieh means to separate, to twist or to offset with a spiral motion, often with the metacarpal and carpal bone area of the thumb as the contact point. Lieh is often translated as "Split."

Chou (肘, zhǒu) - To strike or push with the elbow. Usually translated as "Elbow Strike" or "Elbow Stroke" or just plain "Elbow."

K'ao (靠, kào) - To strike or push with the shoulder or upper back. The word k'ao implies leaning or inclining. Usually translated "Shoulder Strike," "Shoulder Stroke" or "Shoulder."

The Five Steps (五步 wǔ bù):

Chin Pu (進步 jìn bù) - Forward step.

T'ui Pu (退步 tùi bù) - Backward step.

Tsuo Ku (左顧 zǔo gù) - Left step.

You P'an (右盼 yòu pàn) - Right step.

Chung Ting (中定 zhōng dìng) - The central position, balance, equilibrium. Not just the physical center, but a condition which is expected to be present at all times in the first four steps as well, associated with the concept of rooting (the stability said to be achieved by a correctly aligned, thoroughly relaxed body as a result of correct T'ai Chi training).

The Eight Gates are said to be associated with the eight trigrams (八卦 bā guà) of the I Ching, the Five Steps with the five cosmological elements of the Taoist Wu Hsing (五行 wǔ xíng); metal, wood, water, fire and earth. Collectively they are sometimes referred to as the "Thirteen Postures of T'ai Chi Ch'uan" and their combinations and permutations are catalogued more or less exhaustively in the different styles of solo forms which T'ai Chi is mostly known for by the general public. Pushing hands is practiced so that students have an opportunity for "hands-on" experience of the theoretical implications of the solo forms. Traditional internal teachers say that just training solo forms isn't enough to learn a martial art, that without the pushing hands reflex and sensitivity to another's movements and intent are lost. Each component is seen as equally necessary, yin and yang, for realizing the health, meditative, and self-defence applications.

Pushing hands trains these technical principles in ever increasing complexity of patterns. At first students work basic patterns, then patterns with moving steps coordinated in different directions, patterns at differing heights (high, middle, low and combinations) and then finally different styles of "freestyle" push hands, which lead into sparring that combines closing and distancing strategies with long, medium and short range techniques. These exchanges are characterized as "question and answer" sessions between training partners; the person pushing is asking a question, the person receiving the push answers with their response. The answers should be "soft," without resistance or stiffness. The students hope to learn to not fight back when pushed, but rather to allow the direction of the push, the intent of the one asking, to determine their answer. The intent thereby is for the students to condition themselves and their reflexes to the point that they can meet an incoming force in softness, move with it until they determine its intent and then allow it to exhaust itself or redirect it into a harmless direction. The degree to which students maintain their balance while observing these requirements determines the appropriateness of their "answers." The expression used in some T'ai Chi schools to describe this is "Give up oneself to follow another." The eventual goal for self-defence purposes is to achieve meeting the force, determining its direction and effectively redirecting it in as short a time as possible, with examples provided of seemingly instantaneous redirections at the highest levels of kung fu by traditional teachers. Pushing hands also teaches students safety habits in regard to their own vital areas, especially acupressure points, as well as introducing them to the principles of chin na and some aspects of the manipulative therapy or tui na also taught in traditional T'ai Chi Ch'uan schools. At a certain point, pushing hands begins to take on aspects of ch'i kung, as the students learn to coordinate their movements in attack and defense with their breathing.

See also

• Chi Sao
• Ching
• Nei chin
• Taijitu
• Tao Te Ching
• Wudangshan

A time-space diagram of a peristaltic wave after a water swallow. High pressure values are red, zero pressure is blue-green. The ridge in the upper part of the picture is the high pressure of the upper esophageal sphincter which only opens for a short time to let water pass.

Peristalsis is the process of involuntary wave-like successive muscular contractions by which food is moved through the digestive tract. The large, hollow organs of the digestive system contain muscles that enable their walls to move. The movement of organ walls can propel food and liquid and also can mix the contents within each organ. Typical movement of the esophagus, stomach, and intestine is called peristalsis. The action of peristalsis looks like an ocean wave moving through the muscle. The muscle of the organ produces a narrowing and then propels the narrowed portion slowly down the length of the organ. These waves of narrowing push the food and fluid in front of them through each hollow organ.

The process of peristalsis is used by peristaltic pumps.

Peristalsis is also used at oviducts, ureters and other tube-like organs.

In the digestive tract, the muscularis externa (which consists of circular and longitudinal muscle) propels the material along the alimentary canal. During a peristaltic movement, the circular muscles contract behind the digested material; then a contraction of the longitudinal muscle follows which pushes the digested food further along the oesophagus. (These peristaltic movements also occur in the large and small intestines.)

The word is derived from New Latin and comes from the Greek peristaltikos, peristaltic, from peristellein, "to wrap around," and stellein, "to place."

As opposed to the more continuous peristalsis of the small intestines, fecal contents are propelled into the large intestine by periodic Mass Movements. These mass movements occur anywhere from 1-3 times per day, occur in the large intestines and colon, and help propel the contents from the large intestine, through the colon, to the rectum.

External link

• Interactive 3D display of swallow waves