Four chambers
The human heart contains four chambers. The two upper chambers are the atria, while the two lower chambers are the ventricles.
| Chamber | Blood received or pumped |
|---|---|
| Right atrium | Receives deoxygenated blood returning from the body. |
| Right ventricle | Pumps deoxygenated blood towards the lungs. |
| Left atrium | Receives oxygenated blood returning from the lungs. |
| Left ventricle | Pumps oxygenated blood towards the body. |
Keeping the two sides separate
A muscular wall called the septum separates the left and right sides of the heart.
This separation prevents oxygenated blood on the left side from mixing with deoxygenated blood on the right side.
- Right side: contains deoxygenated blood.
- Left side: contains oxygenated blood.
- Septum: separates the two sides.
Exam Tip: Heart diagrams are labelled as though the heart belongs to a person facing you. The anatomical right side of the heart can therefore appear on the left of the page; use the chamber labels rather than relying on page position.