What is physiology?

• A. The study of function at many levels
• B. The study of structure
• C. The study of anatomy
• D. The science of cells

Answer: (A)

Physiology is about how the body and its parts work—the functions and processes that keep life going. It looks at how mechanisms operate across multiple levels, from molecules and cells to tissues, organs, and the whole organism, and how these processes are regulated to maintain homeostasis. For example, understanding how the heart pumps blood, how neurons transmit signals, or how hormones coordinate digestion all illustrate physiological function in action.

The other descriptions focus on structure rather than function—for instance, studying anatomy emphasizes form and organization, while the science of cells or cytology centers on cellular structure and behavior. So the description that best fits physiology is the study of function at many levels.