Blood vessels part 2

Blood vessels

• All blood vessels- inner layer/ lining- made from a single layer of cells- endothelium
• Particularly smooth- reduce friction with flowing blood

Arteries

• Carry blood away from heart- high pressure
• Small lumen- maintain pressure
• Thick walls- contain collagen- high strength
• Wall has elastic tissue- wall can stretch & recoil when heart pumps- recoiling maintains high pressure while heart relaxes
• Wall contains smooth muscle- can contract & constrictthe arter- contriction narrows the lumen (in aterioles- limits blood flow to certain organs or tissues- can be directed to other tissues)
• Endothelium is folded & can unfold when artery stretches

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