Blood vessels Flashcards
What are the parts of the blood vessel?
elastic fibres - stretch and recoil, make walls flexible
smooth muscle - contracts or relax to change the size of the lumen
collagen - maintain shape and volume of the vessel
What is the function and structure of the arteries?
carry oxygenated bulb (except in the pulmonary and umbilical artery)
thick walls - has to withstand force from the heart pumping
elastic fibres help even out surges of blood to create a continuous flow
What is the structure and function of the capillaries?
link arterioles and venules
small lumen - diameter of a red blood cell
site of substance exchange
have gaps
made from flattened endothelial cells
What adaptations do the capillaries have?
large surface area for diffusion
greater cross sectional area, slows blood, more time for exchange
thin diffusion distance
walls are one cell thicj
What are the function of veins?
carry blood from the cells towards the heart, with the exception of the pulmonary and umbilical vein
venules carry deoxygenated blood from the capillaries to the vein
What is the structure and features of the vein?
continuous blood flow
low pressure, little elastic fibre as they dont need to stretch in comparison to collagen
wide lumen and smooth thin lining so blood can flow easily
contain valves
What adaptations do veins have to move blood under loiw pressure and against gravity?
valves at intervals, closed when blood flows backwards
many big veins run through muscles, when they contract is squeezes blood towards the heart
breathing movements of the chest act as pump to move blood
