The term physiology -physio meaning native and logos meaning discourse, is a Greek word, a synonym for natural philosophy.
As the evolutionary processes progressed, the need for a better functioning (viability) system became necessary. Thus, multicellularity evolved. These lead to the formation of group of cells performing function in a responsible*manner. Similarity between cells helped them to group together. Thus, cells which are similar in structure and function formed a group called 'tissues'.The tissues further were responsible for the development . of an organ. Various organs lead to the formation of organ systems. These. organ systems contributed to an individual organism. This organism was able to hction better because of division of labour.
Physiology, therefore, is the study of the physical and chemical processes that take place in living organisms during the performance of life functions. It is concerned with such basic activities as reproduction, growth, metabolism, excitation and contraction as they are carried out within the fine structure - the cells, tissues, organs and organ systems of the body.
Physiology is intimately linked with anatomy and was historically considered a part of medicine. Its emphasis on investigating biological mechanisms with the tools of physics and chemistry made physiology a distinct discipline in the 19th century. The tendency today, however, is toward a fragmentation and merging with the many specialized branches of the life sciences. Three broad divisions are recwnized: general physiology,concerned with basic processes common to all life forms; the physiology and functional anatomy of humans and other animals, including pathology and comparative studies;and plant physiology, which include photosynthesis and other processes pertinent to plant life.
"Thales of Miletos" is known as the first physiologist, who lived around 600BC. The modem world calls "William Harvey" as the first physiologist (1578-1657). Herman Bochaave, a physician at Laden, described physiology as the science of body functions.All~recht von HaIIer wrote the first textbook ofphysiology. Some famous physiologists include Francois Magendie, Johannes Muller, Carl Ludwig, Claude Bernard, Walter Cannon, Hermann Helmholtz etc. H. Helmholtz also proposed law of conservation of energy, invented ophthalmoscope, proposed a theory of colour vision, physiology of hearing etc. Ludwig invented the Kymograph, which served as an important tool in understanding of various mechanical events during neuro-muscular transmission and muscle contraction.
Antony Van Leeuwenhoek's microscopes threw a lot of light in understanding the inner aspects of a cell. The observations made by Robert Hooke on a cork cell opened further avenues for exploring more about the cell. He also observed that the cells had different shapes and structures, which were observed in a leaf, as well as, in a liver cell. Though they differed in structural details, they could be viewed as a variation arising on a common theme. These variations were unique which attributed to a tissue. These observations culminated in formation of the cell theory - by Schwann and Schleiden (1939) - about which we shall learn in the next unit.
Among the most important advances of the 20th century are the discovery of new hormones, recognition of the role of vitamins, discovery ofblood types, development of the electrocardiograph and electroencephalograph, to record the activity of the heart and brain, discovery of the cause and cure of pernicious anaemia by George Richards Minot, William Parry Murphy and George Hoyt Whipple and greater understanding of metabolism, the role of enzymes and the immune system.
The discussion above presented a brief insight into the contributions made by different scientists in the development of physiology as'a discipline.