Physiology

Physiology (/ˌfɪziˈɒlədʒi/; from Ancient Greek φύσις (physis) 'nature, origin', and -λογία (-logia) 'study of') is the scientific study of the normal function in living systems. A sub-discipline of biology, its focus is in how organisms, organ systems, organs, cells, and bio-molecules carry out the chemical or physical functions that exist in a living system. Given the size of the field it is divided into, among others, animal physiology (including that of human), plant physiology, cellular physiology, microbial physiology (see microbial metabolism), bacterial physiology, and viral physiology. Nobel Prize in Physiology or Medicine is awarded to those who make significant achievements in this discipline since 1901 by the Royal Swedish Academy of Sciences. In medicine, a physiologic state is one occurring from normal body function, rather than pathologically, which is centered on the abnormalities that occur in animal diseases, including humans.

History

Physiological studies date back to ancient civilizations of India, Egypt alongside anatomical studies but did not utilize dissections and vivisection. The study of human physiology as a medical field dates back to at least 420 BC to the time of Hippocrates, also known as the "father of medicine." Hippocrates incorporated his belief system called the theory of humours, which consisted of four basic substance: earth, water, air and fire. Each substance is known for having a corresponding humour: black bile, phlegm, blood and yellow bile, respectively. Hippocrates also noted some emotional connections to the four humours, which Claudis Galenus would later expand on. The critical thinking of Aristotle and his emphasis on the relationship between structure and function marked the beginning of physiology in Ancient Greece. Like Hippocrates, Aristotle took to the humoral theory of disease, which also consisted of four primary qualities in life: hot, cold, wet and dry. Claudius Galenus (c. ~130–200 AD), known as Galen of Pergamum, was the first to use experiments to probe the functions of the body. Unlike Hippocrates though, Galen argued that humoral imbalances can be located in specific organs, including the entire body. His modification of this theory better equipped doctors to make more precise diagnoses. Galen also played off of Hippocrates idea that emotions were also tied to the humours, and added the notion of temperaments: sanguine corresponds with blood; phlegmatic is tied to phlegm; yellow bile is connected to choleric; and black bile corresponds with melancholy. Galen also saw the human body consisting of three connected systems: the brain and nerves, which are responsible for thoughts and sensations; the heart and arteries, which give life; and the liver and veins, which can be attributed to nutrition and growth. To top it off, Galen was also the founder of experimental physiology. And for the next 1,400 years, Galenic physiology was a powerful and influential tool in medicine.

Jean Fernel (1497–1558), a French physician, introduced the term "physiology".

Oil painting depicting Claude Bernard, the father of modern physiology, with his pupils

In the 19th century, physiological knowledge began to accumulate at a rapid rate, in particular with the 1838 appearance of the Cell theory of Matthias Schleiden and Theodor Schwann. It radically stated that organisms are made up of units called cells. Claude Bernard's (1813–1878) further discoveries ultimately led to his concept of milieu interieur (internal environment), which would later be taken up and championed as "homeostasis" by American physiologist Walter B. Cannon in 1929. By homeostasis, Cannon meant "the maintenance of steady states in the body and the physiological processes through which they are regulated." In other words, the body's ability to regulate its internal environment. It should be noted that, William Beaumont was the first American to utilize the practical application of physiology.

1858- Joseph Lister studied the cause of blood coagulation and inflammation that resulted after previous injuries and surgical wounds. He later discovered and implemented antiseptics in the operating room, and as a result decreases death rate from surgery by a substantial amount.

1891- Ivan Pavlov performed research on "conditional reflexes" that involved dogs' saliva production in response to a plethora of sounds and visual stimuli.

In the 20th century, biologists also became interested in how organisms other than human beings function, eventually spawning the fields of comparative physiology and ecophysiology. Major figures in these fields include Knut Schmidt-Nielsen and George Bartholomew. Most recently, evolutionary physiology has become a distinct subdiscipline.

1910 – August Krogh, in 1920 won the Nobel Prize for discovering how, in capillaries, blood flow is regulated.

1954- Andre Huxley and Hugh Huxley, alongside their research team, discovered the sliding filaments in skeletal muscle, known today as the sliding filament theory.

Today, and times before, physiologists continuously trying to find answers to important questions concerning how populations interact, the environment on earth, and in single cell functions.

Subdisciplines

There are many ways to categorize the subdiscplines of physiology:

• based on the taxa studied: human physiology, animal physiology, plant physiology, microbial physiology, viral physiology
• based on the level of organization: cell physiology, molecular physiology, systems physiology, organismal physiology, ecological physiology, integrative physiology
• based on the process that causes physiological variation: developmental physiology, environmental physiology, evolutionary physiology
• based on the ultimate goals of the research: applied physiology (e.g., medical physiology), non-applied (e.g., comparative physiology)

Human physiology

Main article: Human body § Human physiology

The human skull at birth, with its fontanelles, presents many important anatomical and physiological features.

Human physiology seeks to understand the mechanisms that work to keep the human body alive and functioning, through scientific enquiry into the nature of mechanical, physical, and biochemical functions of humans, their organs, and the cells of which they are composed. The principal level of focus of physiology is at the level of organs and systems within systems. The endocrine and nervous systems play major roles in the reception and transmission of signals that integrate function in animals. Homeostasis is a major aspect with regard to such interactions within plants as well as animals. The biological basis of the study of physiology, integration refers to the overlap of many functions of the systems of the human body, as well as its accompanied form. It is achieved through communication that occurs in a variety of ways, both electrical and chemical.

Much of the foundation of knowledge in human physiology was provided by animal experimentation. Physiology is the study of function and is closely related to anatomy which is the study of form and structure. Due to the frequent connection between form and function, physiology and anatomy are intrinsically linked and are studied in tandem as part of a medical curriculum.

Gender equality and prominent early female contributors

Initially, women were largely excluded from official involvement in any physiological society. The American Physiological Society, for example, was founded in 1887 and included only men in its ranks. In 1902, the American Physiological Society elected Ida Hyde as the first female member of the society. Hyde, a representative of the American Association of University Women and a global advocate for gender equality in education, attempted to promote gender equality in every aspect of science and medicine.

Soon thereafter, in 1913, J.S. Haldane proposed that women be allowed to formally join The Society of Physiology, which had been founded in 1876. On 3 July 1915, six women were officially admitted into The Society. These six included Florence Buchanan, Winifred Cullis, Ruth C. Skelton, Sarah C. M. Sowton, Constance Leetham Terry, and Enid M. Tribe. Male members of The Society submitted each of these women for consideration and then voted on whether or not the women's accomplishments and potential merited membership in The Society.

Though the acceptance of women into these prestigious physiological societies did not mark an end to inequality, it was a pivotal moment in determining the course of the next century.

Women in modern physiology

Gerty Cori, along with husband Carl Cori, received the Nobel Prize in Physiology or Medicine in 1947 for their discovery of the phosphate-containing form of glucose known as glycogen, as well as its function within eukaryotic metabolic mechanisms for energy production. Moreover, they discovered the Cori cycle, also known as the Lactic acid cycle, which describes how muscle tissue converts glycogen into lactic acid via lactic acid fermentation. The lactic acid yield is subsequently carried by the bloodstream to the liver where it is converted into glycogen, then broken down into glucose, which will be carried back to the muscle tissue via the circulatory system and converted back to glycogen for use as an energy source.

Gertrude Elion, along with George Hitchings and Sir James Black, received the Nobel Prize for Physiology or Medicine in 1988 for their development of drugs employed in the treatment of several major diseases, such as leukemia, some autoimmune disorders, gout, malaria, and viral herpes. Their main branch of research was the biochemical analysis of the similarities and differences between normal cells and possibly malignant structures including cancer cells, bacteria, viruses, and other pathogens.

Linda B. Buck, along with Richard Axel, received the Nobel Prize in Physiology or Medicine in 2004 for their discovery of odorant receptors and the complex organization of the olfactory system.

Françoise Barré-Sinoussi, along with Luc Montaginer, received the Nobel Prized in Physiology or Medicine in 2008 for their work on the identification of the Human Immunodeficiency Virus (HIV), the cause of Acquired Immunodeficiency Syndrome (AIDS). Through dissection of an infected patients’ lymph node, they determined that AIDS was caused by a retrovirus known as HIV. Their work led to the development of new antiviral drugs and novel diagnostic methods.

Elizabeth Blackburn, along with Carol Greider and Jack Szostak, was awarded the 2009 Nobel Prize for Physiology or Medicine for the discovery of the genetic composition and function of telomeres and the enzyme called telomerase. Her studies included the interactions of these cellular components and their roles in cancer and aging.

Susan Wray, who holds a Ph.D. in Cellular and Molecular Physiology, researched and published her paper (on March 15, 2015) about the inhibitory effect of Visfatin and Leptin on human and rat myometrial contractility. Results showed that visfatin inhibits myometrial contractility more than leptin. Data additionally suggests that the increased output of visfatin and leptin in obese pregnant women may impair uterine contractility resulting in an unplanned Caesarean delivery.

See also

• Applied physiology
• Defense physiology
• Exercise physiology
• Fish physiology
• Insect physiology
• List of physiologists
• Physiome
• Somatopsychic

External links

• The Physiological Society
• physiologyINFO.org public information site sponsored by The American Physiological Society

Bibliography

Human physiology

• Widmaier, E.P., Raff, H., Strang, K.T. Vander's Human Physiology. 11th Edition, McGraw-Hill, 2009.
• Marieb, E.N. Essentials of Human Anatomy and Physiology. 10th Edition, Benjamin Cummings, 2012.

Animal physiology

• Hill, R.W., Wyse, G.A., Anderson, M. Animal Physiology, 3rd ed. Sinauer Associates, Sunderland, 2012.
• Moyes, C.D., Schulte, P.M. Principles of Animal Physiology, second edition. Pearson/Benjamin Cummings. Boston, MA, 2008.
• Randall, D., Burggren, W., and French, K. Eckert Animal Physiology: Mechanism and Adaptation, 5th Edition. W.H. Freeman and Company, 2002.
• Schmidt-Nielsen, K. Animal Physiology: Adaptation and Environment. Cambridge & New York: Cambridge University Press, 1997.
• Withers, P.C. Comparative animal physiology. Saunders College Publishing, New York, 1992.

Plant physiology

• Larcher, W. Physiological plant ecology (4th ed.). Springer, 2001.
• Salisbury, F.B, Ross, C.W. Plant physiology. Brooks/Cole Pub Co., 1992
• Taiz, L., Zieger, E. Plant Physiology (5th ed.), Sunderland, Massachusetts: Sinauer, 2010.

Fungi physiology

• Griffin, D.H. Fungal Physiology, Second Edition. Wiley-Liss, New York, 1994.

Protist physiology

• Levandowsky, M. Physiological Adaptations of Protists. In: Cell physiology sourcebook: essentials of membrane biophysics. Amsterdam; Boston: Elsevier/AP, 2012.

Algae physiology

• Lobban, C.S., Harrison, P.J. Seaweed ecology and physiology. Cambridge University Press, 1997.
• Stewart, W. D. P. (ed.). Algal Physiology and Biochemistry. Blackwell Scientific Publications, Oxford, 1974.

Protozoa physiology

• Levandowski, M., Hutner, S.H. (eds). Biochemistry and physiology of protozoa. Volumes 1, 2, and 3. Academic Press: New York, NY, 1979; 2nd ed.
• Laybourn-Parry J. A Functional Biology of Free-Living Protozoa. Berkeley, California: University of California Press; 1984.

Bacterial physiology

• El-Sharoud, W. (ed.). Bacterial Physiology: A Molecular Approach. Springer-Verlag, Berlin-Heidelberg, 2008. ISBN 9783540749202
• Kim, B.H., Gadd, M.G. Bacterial Physiology and Metabolism. Cambridge, 2008. ISBN 9780521712309
• Moat, A.G., Foster, J.W., Spector, M.P. Microbial Physiology, 4th ed. Wiley-Liss, Inc. New York, NY, 2002. ISBN 9780471461197