Blood vessels Flashcards
What is the overall primary purpose of blood vessels?
to ensure rapid delivery of oxygen and nutrients and bring them close enough to cells for diffusion to take place
Describe the pathway of circulation through the blood vessels in the body?
-blood leaves heart via artery (carries oxygenated blood away from heart)
-As it moves down the body it divides into small arteries then arterioles
-then further break down into capillaries (where diffusion takes place & also collects waste products and transport them back to heart)
-Then travel thru venules (allow blood to move away from capillary)
-Into Veins (carry deoxygenated blood back to heart)
What are the 2 types of artery?
elastic or muscular
Artery-mean diameter, wall thickness and layers containing?
-4mm
-1mm
-endothelium
-elastic tissue
-smooth muscle
-fibrous tissue
Arteriole-mean diameter, wall thickness and layers containing?
30 micro meteres
6 micro meteres
-endothelium
-smooth muscle
Capillary-mean diameter, wall thickness and layers containing?
8 micrometeres
0.5 micrometres
-endothelium
venule-mean diameter, wall thickness and layers containing?
20 micrometeres
1 micrometres
-endothelium
–fibrous tissue
vein-mean diameter, wall thickness and layers containing?
5mm
0.5mm
-endothelium
-elastic tissue
-smooth muscle
-fibrous tissue
What is the reservoir holding within the venous system of total blood when at rest?
65% of total blood
Describe the structural characteristic of arteries and why they have this structure?
-have thick walls and smooth muscle layer
-They carry blood away from the heart & blood is pumped out of the heart at a high pressure
-The thick walls help to withstand the high pressure
Describe the structural characteristic of capillaries and why they have this structure?
-Have extremely thin walls compared to other blood vessels ——–
Capillaries is where a point of exchange takes place
-thin walls allow for short diffusion distance
What are the 3 ways in which exchange takes place within capillaries?
-diffusion(the movement of gases eg.O2, CO2)
-transcytosis (larger lipid-insoluble molecules transported across enclosed within vesicles)
- bulk flow (mass movement of fluid- pressure driven)
what is the movement of substances between endothelial cells within capillaries called?
paracellular pathway
what is the movement of substances through endothelial cells within capillaries called?
transendothelial transport
What are the 3 different types of capillaries called and what is the structure of each?
-Continuous- found in skin/ muscles, Structure: endothelial cells provide uninterrupted lining
-Fenestrated- found in kidneys, intestines, endocrine organs, structure: contain large pores
-Discontinuos- found in liver, bone marrow, spleen, structure: endothelial lining few tight junctions and large intercellular clefts
Describe the structural characteristic of veins and why they have this structure?
-carry blood back towards the heart
-Blood is low pressure so veins have thin walls and valves to help blood flow back to heart
What are the 4 different layers that make up a blood vessel called?
-Lumen
-tunica intima
-tunica media
-tunica externa
what is the lumen?
transport area
-a hollow passageway where blood flows
what is the tunica intima and where is it in the blood vessels?
inner most layer
-arteries- endothelium, basement membrane & internal elastic lamina
-Veins- endothelium & basement membrane
-Capillaries- endothelium & internal elastic lamina
What is the endothelium and what does it do?
made up of many endothelial cells- releases nitric oxide- allows for widening of a blood vessel to increase blood flow
what is the tunica media and where is it in the blood vessels?
middle layer
(arteries-smooth muscle and elastic lamina)
(veins-smooth muscle)
-Important within role of vasodilation (making lumen bigger) and vasoconstriction (making lumen smaller)
what is the tunica externa and where is it in the blood vessels?
outer layer
-in arteries & veins
-made up primarily of collagen fibres
-Role is to protect and reinforce vessel and anchor it to its surroundings
What is the response of the blood vessels to acute exercise?
-blood vessels need to increase delivery of blood flow to muscles and increase removal of substances
-blood flow is redistributed from areas of low demand to areas of high metabolic demand, eg.muscles
-happens by vasodilation and vasoconstriction
Describe the process of vasodilation?
-as we exercise increase in cardiac output, increase in blood flow- blood travels thru blood vessel and applies friction to endothelial layer
-nitric oxide is produced an then diffuses thru the membrane into smooth muscle causing relaxation and the vessel to widen, allowing more blood to flow thru
Desricbe the process of vasoconstriction?
-increased contraction of smooth muscle, so lumen layer gets smaller, restricting blood flow thru the vessel
-caused by increase in sympathetic nerve activity-signal is sent to outside of blood vessel and acts on smooth muscle, causing contrqaction
In response to exercise what features do the veins have in order to help blood flow back to heart?
-Valves- to ensure blood goes towards heart, preventing backflow
-muscle pump and respiratory pump: as we start to exercise muscles tart to contract, veins therefore act as pump in order to force blood back to heart
