Module 8: The structure and function of the cardiovascular system

The Body in Action

1. Introduction to the cardiovascular system
2. The heart
   1. Structure of the heart
   2. The heart valves
3. Labelling the heart activity
4. Circulatory system
   1. Animation of the circulation systems
5. Blood vessels
   1. Arteries
   2. Capillaries
   3. Veins
6. Characteristics of blood vessels activity
7. Function of the cardiovascular system
8. Function of the blood

The heart valves

Blood is pumped through the chambers of the heart aided by four heart valves which prevent the backflow of blood, ensuring a one way flow. They consist of two or three flaps (cusps) of tissue that open to let blood through then seal shut to prevent any backflow.

Atrioventricular valves (tricuspid and bicuspid valves)

• The tricuspid valve is located between the right atrium and right ventricle. Deoxygenated blood is returned from the body via the vena cava into the right atrium. From the right atrium the blood passes through the tricuspid valve into the right ventricle.
• The bicuspid (also referred to as the mitral valve) is located between the left atrium and left ventricle. After receiving a fresh supply of oxygen the blood is returned from the lungs via the pulmonary vein into the left atrium. From the left atrium the blood passes through the bicuspid valve into the left ventricle.

Semilunar valves

• The pulmonary semilunar valve is located between the right ventricle and the pulmonary artery. The right ventricle pumps blood through the pulmonary semi-lunar valve into the pulmonary artery which carries the blood to the right and left lungs.
• The aortic semilunar valve is located between the left ventricle and the aorta. The left ventricle pumps blood leaves through the aortic semilunar valve into the aorta which ultimately carries the oxygenated blood out to all parts of the body.