Short answer
Anatomy asks what the human body is made of and how its parts are arranged; physiology asks how those parts work. They describe the same body through complementary questions, because structure helps explain function and function helps explain the significance of structure. 1 2
On this page
At a glance
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| Question or attribute | Anatomy | Physiology |
|---|---|---|
| Main focus | Body structure | Body function |
| Typical question | How are these parts arranged? | How do these parts work together? |
| Hand example | Thumb positioned opposite the fingers | Pinching, grasping, and manipulating tools |
| Explanatory emphasis | Form and organization | Chemistry, physics, and mechanisms |
These are differences in emphasis, not two unrelated subjects. 1
What each thing is
Anatomy studies bodily structure; MedlinePlus frames it through descriptions and pictures of body parts and organ systems. Physiology studies the chemistry and physics of those structures and their coordinated activity. Much physiological study concerns homeostasis: the maintenance of steady internal conditions. 2 1
Key differences
The central difference is the question being investigated, not the body part involved. A structural description explains an arrangement; a functional explanation addresses what that arrangement enables and how it works. Physiology therefore goes beyond naming an activity to investigating its mechanisms, including molecular and ionic interactions. 1
How to tell them apart
A practical rule is to ask whether a passage primarily describes parts and their arrangement or explains an activity and its mechanism. The first emphasis is anatomical; the second is physiological. The limit is that a single explanation may do both: eyelid movement depends on the arrangement and activity of its nerves and muscles. 1
Where they overlap
Structure and function meet within explanations of the same body part. OpenStax connects the eyelid’s thin form with its rapid movement, then connects that movement with nerves, muscles, molecules, and ions. Neither perspective replaces the other; together they connect a visible action with the structures and processes supporting it. 1
Edge cases
A statement about molecular shape can sit at the boundary. OpenStax notes that certain molecules require a particular three-dimensional structure to function. Describing that shape emphasizes structure; explaining why it matters emphasizes function. This also shows why physiology should not be identified solely by descriptions of visible movement. 1
Why the distinction exists
The distinction separates two useful explanatory tasks: describing organization and explaining operation. OpenStax’s hand example shows why both matter: the thumb’s alignment becomes more meaningful when considered alongside pinching, grasping, and tool use. Studying structure without its functional context can leave its significance unclear. 1
Common misconceptions
Anatomy is not limited to naming individual organs: systemic anatomy can examine all the skeletal muscles as a body system. Nor must a resource labeled anatomy contain only structural material. MedlinePlus’s anatomy page also links to a resource about how eyes work, illustrating that topic labels can accommodate related functional questions. 1 2
Examples
Two cases apply the distinction. For the eyelid, describing its thin flap and the arrangement of its nerves and muscles is anatomical; explaining its rapid clearing and reopening action is physiological. For the hand, describing the thumb opposite the four fingers is anatomical; explaining how that arrangement supports pinching and grasping brings in physiology. Both cases concern one body part, not competing descriptions of different parts. 1