Physiology (Latin: physiologia, from Greek: φυσιολογια from φυσισ-, physis-, nature, + λογος, logos, speech or study) is the study of how living things function, and therefore, is part of of biology. Just which part has changed focus over the years. Historically, subjects like biochemistry, pharmacology and immunology, have each, serially, been considered a primary focus of physiology. As those fields of study developed and came to be regarded as separate disciplines, each split off as a distinct area of biological study, with separate departments in universities, separate journals for the publication of original research, and xxxx. Despite that, aspects of each of these fields still remain at the heart of the science of life functions.
What distinguishes a particular topic from being squarely within the field of physiology, rather than at the core of a related field? One criterion is the concept of physiological relevance. Is the intrinsic importance of the phenomenon vital for the normal functioning of the organism involved? If the answer is "yes", than that phenomenon counts as physiology.
When a drug is absorbed by Thus a pharmacological response merely demonstrates the presence of functional receptors, a physiological response entails showing the involvement of an endogenous ligand in an effect that has demonstrably adaptive consequences.
A relatively recent offshoot of physiology is the field of biophysics.
Within physiology, there has been a traditional divide between the study of plants (Botany) and the study of animals (Zoology). In centuries past, when whole organisms were universally studied in biology, this XXX made sense. As the study of life functions has xxx to a microscopic and molecular level, many processes within the bodies of plants and animals have been recognized as being very similar. So, although both birds and trees absorb water into their bodies, for historic reasons, animal physiologists use osmotic pressure (π) whereas plant physiologists use osmotic potential (ψs) to describe xxxx.
This article describes general principles of physiology,
Scale: molecules to systems
See also: Systems biology, Life, Human physiology
Important physiologists of the Twentieth Century
Major names in the history of physiology in the first half of the 20th century might include Hodgkin and Huxley (physiology of the nervous impulse), Starling (endocrine scretions), Ringer (frog heart), Katz (neuromuscular junction), Adrian (nerve impulses), Sharpey-Shafer (adrenals and other endocrine systems), Sherrington (spinal reflexes), Dale (transmitter release), Eccles (synapses), Geoffrey Harris (neuroendocrine systems) (a very UK-centric list of our glory days), but also Nernst, Cajal, Banting and Best, Howard Florey. All living thing ( by most definitions) are composed of cells, and so the life functions that are present in every cell, like metabolism are an important part of physiology. Specialized functions of cells and organs are also included in this branch of biology. So, in the heart, for example, the electrical conducting system for the co-ordination of the beat of muscle cells is an important part of cardiac physiology. In Medicine, normal healthy functioning of tissues is called physiologic, and pathophysiology describes the specific mechanisms of disease processes.
Some fields within physiology focus on certain kinds of living things, such as microbial physiology.