Anatomy & Physiology · Chapter 1

Levels of Structural Organization

The body is built in six nested levels — each one assembled from the level below it. Zoom out from a single atom all the way to a whole human, following one thread: the smooth muscle in a blood-vessel wall.

Chemical level

~0.1 nm
Chemical levelatoms & molecules

Climb the ladder

📷 Reference image
A real labeled figure to compare with the interactive above.
Levels of Structural Organization reference figure
Levels of Structural Organization — OpenStax, CC BY 4.0 (via Wikimedia Commons)