Unit 2 - KA5 - The structure and Function of Arteries, capillaries and veins Flashcards
What is the central space of a blood vessel called?
the lumen
function of the endothelium
lines the central lumen of the artery
the role of an artery
carries blood away from the heart
the function of elastic fibres
in the outer and middle layers allow the artery to strech and contract as the waves of blood arrive.
function of the smooth muscle
allows the diameter of the artery to be reduced to control flow through the vessel
what happens as the blood gets further from the heart
pressure falls
why does pressure fall as the blood gets further away from the heart?
-Because energy has been dissipated during the process of stretching the vessels walls
-As a result of friction against the walls
what are the smallest arteries also know as
arterioles
what do arterioles do?
supply blood to the capillaries where exchange with the tissues takes place.
function of thin walls in capillaries
allows exchange of substances with tissues through their thin walls
vasoconstriction and vasodilation
where smooth muscles surrounding arteries can contract causing vasoconstriction or relax causing vasodilation.
what is the role of vasoconstriction with the control of blood flow
it is used to close down the flow of blood into the capillary beds supplied by these arteries.
what is the role of vasodilation with the control of blood flow
to resupply the tissues with blood, the muscles relax and blood flows again into the capillaries
function of a vein
carry blood back to the heart
why are the walls of veins thinner than those of an arteries?
the blood pressure is far lower
