Blood Vessels Flashcards
Purpose of collagen in vessel walls
It is a tough fibrous protein which makes them strong and durable to withstand pressure
Purpose of elastic fibres in vessel walls
Allow vessels to stretch and recoil to maintain pressure on blood
Purpose of smooth muscle cells in vessel walls
Allow vessels to constrict and dilate to maintain blood pressure
Properties of arteries
Narrow lumen(maintain high pressure),thicker walls(withstand high pressure w/o damage), more collagen smooth muscle and elastic fibres and no valves
Properties of veins
Wide lumen(ensure little resistance to blood flow), thinner walls(for skeletal muscle movement), less collagen and smooth muscle and elastic fibres, valves(blood continues to move to heart)
Properties of capillaries
Thin walls(decrease diffusion distance), form large network near cells(increase SA), narrow lumen(blood flow slows down to allow time for diffusion)
How do arteries maintain pressure on blood
Heart contracts(systole) so blood forced into arteries and elastic walls stretch to accommodate this. Diastole(relaxation of heart) the elasticity of artery walls means they recoil behind the blood which helps to push blood forward. Blood moved along length of artery in this way.
Layers of blood vessels from outside to inside
-outer coat(connective tissue with collagen fibres)
-muscle and elastic tissue
-endothelium(smooth to reduce friction)
-lumen(channel which blood flows along)
How do skeletal muscles assist blood flow in veins
Assisted by contraction of skeletal muscles during movement of limbs and breathing, contraction pushed blood forward towards heart through open valves, when muscles relax the valves close to prevent back flow
How’s does breathing assist blood flow in the veins
Low pressure developed in thorax(chest cavity) when breathing helps draw blood back into heart from veins as fluid moves from high to low pressure
What is a cardiac cycle
One complete sequence of filling and pumping blood
