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The heart - GCSE Biology

The heart is seen from the front in the diagram. So the right side of the heart is shown on the left of the diagram. The left side is on the right side of the diagram.The heart is a muscular pump. When it beats it pumps blood to the lungs and around the body. The amount of blood pumped can be calculated: heart beat x stroke volume = cardiac output

The heart has four chambers. The two atria collect the blood. The two ventricles pump the blood out of the heart.Valves prevent the blood from flowing backwards The septum separates the two sides of the heart.

The right side of the heart pumps de-oxygenated blood (blood not containing oxygen) to the lungs to pick up oxygen. The left side of the heart pumps the oxygenated blood from the lungs around the rest of the body.

Arteries

- Have thick muscular walls

- Carry blood away from the heart ( always oxygeneted apart from the pulmonary artery which goes to the lungs.

- Have small passageways for blood

- Contain blood over high pressure

Veins

- Carry the blood to the heart ( always from the pulmonary vein which goes from the lungs to the heart)

- Have thin walls

- Have larger internal lumen ( the centre cavity in a hollow structure in an organism / cell

- Contains blood under low pressure

Capilaries

- Found in the muscles and lungs

- They are microscopic

- Very low blood pressure

- Where gas exchange takes place. Oxygen passes through the capillary wall and into the tissues, carbon dioxide passes from the tissues into the blood

The four main blood vessels of the heart are:

a) Vena Cava

b) Pulmonary artery

c) Pulmonary Vein

d) Aotra