Cardiovascular System

Fitness for activities Circulation The muscles need to receive nutrients and oxygen. This is one of the three functions of the circulatory system. What is the circulatory system? Essentially it is a pumped system. Fluid is pumped around the body. The fluid: Transports nutrients and oxygen Regulates your body temperature Provides protection against disease

Fitness for activities Circulation Transports nutrients and oxygen Lungs Heart Body Oxygenated blood Deoxygenated blood Oxygenated blood circulates from the lungs to the rest of the body and back to the heart. It also carries glucose, other nutrients, water and waste all around the body.

Fitness for activities Circulation Regulates your body temperature Lungs Heart Body Oxygenated blood Deoxygenated blood As the blood gets close to the surface of your body, it loses heat quickly. This is why your skin goes red when you exercise. Blood comes closer to the surface and loses heat, cooling you down.

Fitness for activities Circulation Provides protection from disease Lungs Heart Body Oxygenated blood Deoxygenated blood Antibodies, which fight infection, are transported around the body by the blood. When exposed to the air, blood clots, sealing wounds from infection and beginning the process of repair.

Fitness for activities Circulation The key element of the circulatory system is the heart which is responsible for pumping the blood all around your body. Right lung Left lung

Fitness for activities Circulation The key element of the circulatory system is the heart which is responsible for pumping the blood all around your body. Right lung Left lung Heart

Fitness for activities Circulation The key element of the circulatory system is the heart which is responsible for pumping the blood all around your body. Aorta – carries oxygenated blood from the heart to the body Right lung Left lung

Fitness for activities Circulation The key element of the circulatory system is the heart which is responsible for pumping the blood all around your body. Pulmonary arteries – carry used blood to the lungs to be reoxygenated Right lung Left lung

Fitness for activities Circulation The key element of the circulatory system is the heart which is responsible for pumping the blood all around your body. Pulmonary veins – carry oxygenated blood from the lungs to the heart Right lung Left lung

Fitness for activities Circulation The key element of the circulatory system is the heart which is responsible for pumping the blood all around your body. Superior vena cava – carries used blood to the heart from the upper body Right lung Left lung

Fitness for activities Circulation The key element of the circulatory system is the heart which is responsible for pumping the blood all around your body. Inferior vena cava – carries used blood to the heart from the lower body Right lung Left lung

Fitness for activities Circulation Deoxygenated blood (blue in the diagram) returns from the body via veins and is pumped to the lungs. The blood is then reoxygenated (red in the diagram) in the lungs and returned to the heart before it is pumped around the body again. When the oxygen content has been reduced by the muscles, the cycle begins again.

Fitness for activities Circulation You can clearly see that each time blood is cycled around the body, it passes through the heart twice. There are effectively two circuits for the blood to pass through.

Fitness for activities Circulation Lungs Heart Body Oxygenated blood Deoxygenated blood We saw this earlier with a simplified diagram of the two circuits. We can now look at this in a little more detail:

Fitness for activities Circulation Lungs Here we see the functions of the four chambers of the heart. Right Atrium Left Atrium Right Ventricle Left Ventricle Note that we are looking at the heart from the front so the left and right seem transposed. Body

Fitness for activities Circulation Lungs The right side of the heart pumps the deoxygenated blood from the body into the lungs. Right Atrium Left Atrium Right Ventricle Left Ventricle In the lungs, the blood is reoxygenated. Body

Fitness for activities Circulation Lungs The left side of the heart pumps the oxygenated blood from the lungs into the body. Right Atrium Left Atrium Right Ventricle Left Ventricle In the body, the muscles remove some of the oxygen as they “burn” energy. Body

Fitness for activities Circulation Lungs The pulmonary circuit is responsible for getting oxygen back into the blood. Pulmonary circuit Right Atrium Left Atrium Right Ventricle Left Ventricle It does this by pumping the blood from the heart, to the lungs and back into the heart again. Body

Fitness for activities Circulation Lungs The systemic circuit is responsible for getting oxygenated blood to where it is needed. Right Atrium Left Atrium Right Ventricle Left Ventricle It does this by pumping the blood from the heart, to the body and back into the heart again. Systemic circuit Body Remember that arteries carry blood out of the heart and veins carry blood into the heart.