It is the biological study of the cell's mechanism and interaction with its environment. It deals with all the normal functions that take place in a living organism. Water absorption by roots, food production in the leaves, and shoot growth towards light are examples of plant physiology. The heterotrophic metabolism of food derived from plants and animals and the use of movement to obtain nutrients are characteristic of animal physiology. In humans it deals with membrane transport, neuron transmission, and muscle contraction. There are two types of cells, Prokaryotes and Eukaryotes of which prokaryotes were the first came into existence and contained no nucleus, due to which their mechanisms are much simpler than the Eukaryotes which evolved later and contain a nucleus enveloping the cell's DNA and nuclear organelles. Certain organisms such as viruses, viroids, prions depend entirely on the physiology of other cells (i.e., cells containing their own physiology), therefore former entities are often not considered to be "living" by the biologists who study them.
Last date updated on July, 2014