Why is physiology called one of the main branches of biology?

Physiology is called one of the main branches of biology. This branch of
biology deals with the biochemical activities of different organs of
organisms. Besides, a detailed description of all the physiological processes
of an organism is found in it. All of these physiological processes are much
important for every organism. Without any of these processes, organism can’t
do their regular activities. That’s why physiology is called one of the main
branches of biology.