A physiologist is a scientist who studies how living things work. While an anatomist might examine the shape and structure of a heart, a physiologist wants to know how it pumps blood, what makes it beat faster during exercise, and how it responds to different conditions. Physiologists investigate the mechanics of life: how muscles contract, how nerves send signals, how the body digests food and turns it into energy.

Physiologists might research how athletes' bodies adapt to training, how the brain processes information, or how plants transport water from their roots to their leaves. Some physiologists focus on humans, others on animals, and some on plants.

Their work often leads to important medical discoveries. For instance, physiologists studying how the pancreas works helped doctors understand and treat diabetes. Others researching muscle function have improved treatments for injuries. A physiologist might spend their day running experiments in a laboratory, measuring heart rates during different activities, or analyzing how cells communicate with each other. They're essentially detectives of the living world, figuring out the “how” behind what organisms do.