The Human Circulatory System
How the heart pumps blood around the body.
The Heart
A muscular, four-chambered organ (two atria, two ventricles) that pumps blood through the body in a double circulation — through the lungs, and through the rest of the body.
Blood Vessels
- Arteries — carry blood away from the heart
- Veins — carry blood back to the heart
- Capillaries — tiny vessels where exchange with tissues occurs
Lesson 21 of 26