Physiologist conducts research into biological functions and activities of human organisms to increase scientific knowledge and develop practical applications in medical and related fields. He/she studies functions and working of the brain, nervous system, sensory organs, glands, respiratory and blood circulation systems and other life processes of the human organism and investigates reactions of life processes and functions to changes in altitude, noise levels, motion, light intensity, temperature, humidity and other environmental factors. He/she applies scientific knowledge to problems of physical fitness, nutrition, human endurance and similar matters.