Physiology (from Greek _gr. φύσις, "physis", "nature, origin"; and _gr. -λογία, "-logia") is the study of the mechanical, physical, and biochemical functions of
living organisms. Physiology has traditionally been divided between plant physiologyand animal physiology but the principles of physiology are universal, no matter what particular organismis being studied. For example, what is learned about the physiology of yeastcells may also apply to humancells.
The field of animal physiology extends the tools and methods of
human physiologyto non-human animal species. Plant physiology also borrows techniques from both fields.Its scope of subjects is at least as diverse as the tree of lifeitself. Due to this diversity of subjects, research in animal physiology tends to concentrate on understanding how physiological traits changed throughout the evolutionary history of animals. Other major branches of scientific study that have grown out of physiology research include biochemistry, biophysics, paleobiology, biomechanics, and pharmacology.
Physiology can trace its roots back more than two millennia to
classical antiquity, to the Greek and Indian medical traditions. The critical thinking of Aristotleand his emphasis on the relationship between structure and function marked the beginning of physiology in Greece, while Claudius Galenus (c. 126-199), known as Galen, was the first to use experiments to probe the function of the body. The ancient Indian books of Ayurveda, the " Sushruta Samhita" and " Charaka Samhita", also had descriptions on human anatomy and physiology.
Middle Ages, the ancient Greek and Indian medical traditions were further developed by Muslim physicians, most notably Avicenna(980-1037), who introduced experimentationand quantificationinto the study of physiology in " The Canon of Medicine". Many of the ancient physiological doctrines were eventually discredited by Ibn al-Nafis(1213-1288), who was the first physician to correctly describe the anatomyof the heart, the coronary circulation, the structure of the lungs, and the pulmonary circulation, for which he is considered the father of circulatory physiology. [Chairman's Reflections (2004), "Traditional Medicine Among Gulf Arabs, Part II: Blood-letting", "Heart Views" 5 (2), p. 74-85  .] He was also the first to describe the relationship between the lungs and the aerationof the blood, the cause of pulsation, [Nahyan A. G. Fancy (2006), "Pulmonary Transit and Bodily Resurrection: The Interaction of Medicine, Philosophy and Religion in the Works of Ibn al-Nafīs (d. 1288)", pp. 224-229, "Electronic Theses and Dissertations", University of Notre Dame. [http://etd.nd.edu/ETD-db/theses/available/etd-11292006-152615] ] and an early concept of capillarycirculation.Dr. Paul Ghalioungui (1982), "The West denies Ibn Al Nafis's contribution to the discovery of the circulation", "Symposium on Ibn al-Nafis", Second International Conference on Islamic Medicine: Islamic Medical Organization, Kuwait ( cf.[http://www.islamset.com/isc/nafis/drpaul.html The West denies Ibn Al Nafis's contribution to the discovery of the circulation] , "Encyclopedia of Islamic World")]
Following from the Middle Ages, the
Renaissancebrought an increase of physiological research in the Western worldthat triggered the modern study of anatomy and physiology. Anatomist William Harveydescribed the circulatory systemin the 17th century, [Zimmer, Carl. 2004. "Soul Made Flesh: The Discovery of the Brain - and How It Changed the World." New York: Free Press.] demonstrating the fruitful combination of close observations and careful experiments to learn about the functions of the body, which was fundamental to the development of experimental physiology. Herman Boerhaaveis sometimes referred to as a father of physiology due to his exemplary teaching in Leiden and textbook 'Institutiones medicae' (1708).
In the 19th century, physiological knowledge began to accumulate at a rapid rate, most notably with
Matthias Schleidanand Theodor Schwann's Cell theorywhich radically stated in 1838 that organisms are made up of units called cells, along with Claude Bernard's (1813-1878) many discoveries that ultimately led to his concept of, interieur (internal environment) which would later be taken up and championed as Homeostasisby American physiologist Walter Cannon(1871-1945).
In the 20th century, biologists also became interested in how organisms other than human beings function, eventually spawning the fields of
comparative physiologyand ecophysiology[Feder, M. E., A. F. Bennett, W. W. Burggren, and R. B. Huey, eds. 1987. "New directions in ecological physiology." Cambridge Univ. Press, New York.] Major figures in these fields include Knut Schmidt-Nielsenand George Bartholomew. Most recently, evolutionary physiologyhas become a distinct subdiscipline [ [http://www.biology.ucr.edu/people/faculty/Garland/GarlCa94.pdf Garland, T., Jr., and P. A. Carter. 1994. Evolutionary physiology. "Annual Review of Physiology" 56:579-621.] ] .
The Physiological Society
* [http://www.intellecttoday.com Scientific Discussion - Physiology]
* [http://www.physiology.info Physiology.info]
* [http://www.physoc.org The Physiological Society]
* [http://www.biol.unt.edu/developmentalphysiology/ Developmental physiology]
* [http://www.the-aps.org/ The American Physiological Society]
* [http://www.biophysics.org/ The Biophysical Society]
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