Physiology is the study of function in living organisms. Based on knowledge of anatomy, physiology seeks to demonstrate the manner in which organs perform their tasks, and in which the body is organized and maintained in a state of homeostasis. Normal responses to various stresses on the whole or on parts of an organism are studied. Important branches of physiology deal with respiration, the circulatory system, the nervous system, the digestive system, the kidneys, the fluid and electrolyte balance, the endocrine glands, and metabolism. Knowledge of physiology is basic to medicine and provides the physician with a perspective in which to view the body's disordered function in disease.