BY: ZABIOULLAH FOKERBUX

6.2.1- Draw and label a diagram of the heart showing the four chambers, associated blood vessels, valves and the route of blood through the heart.

6.2.2- State that the coronary arteries supply heart muscle with oxygen and nutrients

The coronary arteries form part of the aorta, which branch off to the semilunar valve. The role of the coronary arteries is to supply blood to the heart muscles with nutrients and oxygen (for aerobic cell respiration, providing energy for muscle contraction).

6.2.3- Explain the action of the heart in terms of collecting blood, pumping blood, and opening and closing of valves.

The heart is split into four chambers: right and left atrium, and right and left ventricle. The atria are the collecting chambers (collecting blood from the veins at low pressure) and the ventricles are the pumping chambers (pumping blood at high pressure through the arteries to prevent backflow). There is a sequence of contraction (systole) and relaxation (diastole) of the heart muscle in one heartbeat.

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The sequence starts when blood is returning to the heart at low pressure via the atria (from the pulmonary vein and vena cava, relaxation of the atria is called atrial diastole). Oxygenated blood enters the left atrium and deoxygenated blood enters the right atrium. The tricuspid and bicuspid valves are closed. As the blood fills in the atria, the pressure overcomes the pressure of the ventricles and thus opens the valves.

Then the two atria contract simultaneously, this is called atrial systole, forcing the blood into the ventricles.

The ventricles contract, called ventricular systole, this causes the pressure in ...

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