AQA AS Biology Unit 1 3.1.5 The Heart

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3.1.5 The Heart

Heart Structure and Function

Mammals have a double circulatory system;

Pulmonary circulation
Systemic circulation

Right Side (Pulmonary Circulation):

Receives deoxygenated blood from the body via the Vena Cava.
Pumps it to the lungs via the Pulmonary Artery where it is oxygenated.

Left Side (Systemic Circulation):

Receives oxygenated…

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1. Both atria fill with blood.
2. An electrical impulse from the sino-atrial node (SAN) [pacemaker] spreads over the atria causing atrial systole
(contraction). The impulse cannot pass directly to the ventricles due to the band of non-conducting tissue that
separates the atria and the ventricles.

3. Pressure in the…

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Angina ­ Chest pains caused by an inadequate supply of blood (and therefore oxygen) to the heart muscle.

Arteriosclerosis ­ Hardening of the arteries. Associated with old age, the blood vessel walls, particularly of the
arteries, become less elastic and more liable to rupture.

Atheroma ­ The fatty deposit that…

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The build up of an atheroma is usually the result of a combination of risk factors, both environmental and genetic.

1. Diet and blood cholesterol.

Cholesterol is important in cells and your body can make its own cholesterol, but it's also found in a lot of the
foods that we…


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