Explain the mail differences between arteries, veins and capillaries.
Answers
Answer:
arteries- carry pure blood from heart to all parts of the body
veins- carry impure blood from all parts of the body to heart
capillaries- are narrow blood vessels which connects arteries and veins together
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Walls:
=>Arteries have a narrower lumen and have thicker elastic muscular walls that can distend and relax.
=>Veins have a wider lumen and have thinner muscular walls.
=>Capillaries have a thin single cell layer called the endothelium, their walls have narrow pores to allow amoeboid leucocytes to squeeze out. They are extremely thin and minute.
Valves:
=>Arteries do not have valves in them.
=>Veins, especially present in the legs, have pocket valves in them to prevent backflow of blood due to gravity.
=>Capillaries do not have any valves in them.
Pressure and speed:
=>In arteries, blood flows under great pressure and with great speeds.
=>In veins blood flows sluggishly and is directed by valves, flowing under low pressure.
=>In capillaries, blood flows at higher pressures due to very thin and minute nature, the very high hydrostatic pressure allows leucocytes and blood plasma to be squeezed out.