What is the study of how an organism's parts work together?

• A. Anatomy
• B. Biochemistry
• C. Histology
• D. Physiology

Answer: (D)

Understanding how body parts work together—how organs and tissues coordinate to perform complex tasks and keep internal conditions stable—this is physiology. It focuses on function and the way systems interact to sustain life, such as how the heart and blood vessels regulate circulation, how the lungs manage gas exchange, or how nerves and hormones coordinate actions to maintain homeostasis. This functional, integrative view distinguishes physiology from anatomy, which maps structure; histology, which examines tissues under a microscope; and biochemistry, which examines chemical processes and molecules, often at a smaller scale rather than the whole-organism integration. In short, physiology explains the how of living systems—the dynamic processes that let an organism operate as a coordinated whole.