b3-4

Question	Answer
What are the 4 main chambers of the heart?	There are four main chambers (left and right atria and ventricles) of the heart.
Describe how the heart works	Blood enters the atria of the heart. The atria contract and force blood into the ventricles. The ventricles contract and force blood out of the heart. Valves in the heart ensure that blood flows in the correct direction. Blood flows from the heart to the organs through arteries and returns through veins.
What are the 2 circulation systems ?	There are two separate circulation systems, one for the lungs and one for all other organs of the body.
compare arteries and veins	Arteries have thick walls containing muscle and elastic fibres. Veins have thinner walls and often have valves to prevent back-flow of blood.
Describe the function of stents	If arteries begin to narrow and restrict blood flow stents are used to keep them open.
Describe the structure and function of capillaries	In the organs, blood flows through very narrow, thin-walled blood vessels called capillaries. Substances needed by the cells in body tissues pass out of the blood, and substances produced by the cells pass into the blood, through the walls of the capillaries.
Give two differences in the composition of the blood from an artery in the leg and a vein in the leg	• (artery has) more oxygen • (artery has) more glucose • (artery has) less carbon dioxide • (artery has) less lactic acid

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	Created by david doran about 7 years ago