Structure of the Human Heart
- The heart is an organ made of muscle called cardiac muscle which contracts to pump blood around the body
- The heart organ is a double-pump
- Oxygenated blood from the lungs enters the left side of the heart and is pumped to the rest of the body (the systemic circuit)
- The left ventricle has a thicker muscle wall than the right ventricle as it has to pump blood at high pressure around the entire body,
- Deoxygenated blood from the body enters the right side of the heart and is pumped to the lungs (the pulmonary circuit)
- The right ventricle is pumping blood at lower pressure to the lungs
- A muscle wall (called the septum) separates the two sides of the heart
- Oxygenated blood from the lungs enters the left side of the heart and is pumped to the rest of the body (the systemic circuit)
- Blood is pumped towards the heart in veins and away from the heart in arteries
Structure of the heart diagram
Structure of the heart showing the four main chambers, the four main blood vessels and the valves
Examiner Tip
The heart is labelled as if it was in the chest so the left side of a diagram is the right-hand side of the heart and vice versa.
The outside of the heart
- The external surface of the heart is covered in small blood vessels called coronary arteries
- Coronary arteries supply blood to the heart muscle itself
- The blood supply to the heart muscle provides oxygen and glucose for the respiring cardiac muscle cells and removes the waste products of metabolism
The external view of the heart diagram
The external view of the heart showing the coronary arteries surrounding the outside of the heart
Examiner Tip
You will not be required to identify the coronary arteries and veins on diagrams; the above is just for reference and to deepen your understanding of the structure of the heart.