structure of blood vessels

Question 1

what is the structure and function of arteries

Answer 1

carry blood away from heart

Small lumen, for high pressure
Lined with folded endothelium which unfolds when artery wall stretches

Thick wall of collagen for strength and elastic fibres for stretch and recoil as blood pumped creating pulse, also includes smooth muscle so artery can contract and constrict to limit blood flow

Question 2

what is the structure and function of veins

Answer 2

-carry blood back to the heart

larger lumen, to allow easy flow of blood
Lined with endothelium
Thinner wall consisting of smaller amounts of collagen, elastic fibres and smooth muscle - as they do not need to stretch and recoil and do not actively contract and constrict to limit blood flow although they can be flattened by the action of surrounding skeletal muscle.
Main feature: Contain valves to assist blood flow back to the heart and prevent backflow.-

Question 3

what is the structure and function of capillaries

Answer 3

allow exchange of materials between blood and tissue fluid

Tiny lumen diameter same size as a red blood cell. = dcrease diffusion distance = increase rate of diffusion

Capillary wall only consists of endothelium squamous, which are flattened endothelial cells to further assist diffusion distance

Question 4

what is the structure and function of arterioles

venules?

Answer 4

arterioles- deliver blood to capillaries, thinner collagen and elastic layer than arteries due to lower pressure, thicker muscle layer to regulate blood flow into capillaries

venules- receives blood from capillaries before veins, thin walled