Blood Vessels

Arteries, Capillaries and Veins

Arteries

• Carry blood from the heart to the body.
• Thick and muscular walls with elastic tissue to cope with high pressure produced by heartbeat. 
• The inner lining (endothelium) is folded, allowing the artery to expand - also helps cope with pressure.
• All arteries carry oxygenated blood except for the PULMONARY - deoxygenated to the lungs. 

Capillaries

• Substances like glucose and oxygen are exchanged between cells and capillariesvso they are adped for efficient diffusion (one cell thick)
• Capillaries branch off of arteries and connect to veins. 

Veins

• Veins take blood back to the heart under low pressure.
• They are wider than arteries with very little elastic or muscle tissue. 
• Veins contain valves to stop the blood flowing backwards.
• Blood flow through the veins is helped by contraction of the body muscles surrounding them. 
• All veins carry deoxygenated blood except for the PULMONARY - oxygenated blood to the heart from the lungs. 

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