Structure of the Heart
Biology: Cambridge International A Level, topic 8.3.1
Structure
The heart is the muscular organ that pumps blood to and from the lungs and around the body. The heart consists of four chambers and each chamber is very important.
Right atrium
- Deoxygenated blood flows into the right atrium from the body.
- The vein that carries deoxygenated blood into the right atrium is called the vena cava.
- The right atrium is the first chamber that deoxygenated blood flows through.
Right ventricle
- When the walls of the right atrium contracts, deoxygenated blood flows into the right ventricle.
- The atrioventricular valves prevent blood from flowing back into the atria from the ventricles.
- Then the walls of the right ventricle contracts, blood is pumped out of the pulmonary artery to the lungs.
- The semi-lunar valves prevent blood from flowing back into the right ventricle from the pulmonary artery.
Left atrium
- Oxygenated blood flows into the left atrium from the lungs.
- The vein that pumps oxygenated blood into the left atrium is called the pulmonary vein.
Left ventricle
- When the walls of the left atrium contracts, oxygenated blood flows into the left ventricle.
- The atrioventricular valves prevent blood from flowing back into the atria from the ventricles.
- The walls of the left ventricle are considerably thicker than the right ventricle.
- The left ventricle has to transport blood all the way around the body but the right ventricle only has to transport blood to the lungs.
Aorta
- When the left ventricle contracts, blood is pumped out of the heart to the rest of the body.
- Oxygenated blood leaves the heart through the aorta.
- The semi-lunar valves prevent blood from flowing back into the left ventricle from the aorta.
Test yourself on Structure of the Heart
What direction of blood flow is halted by the semi-lunar valves?