Blood vessels

Question 1

What is the overall primary purpose of blood vessels?

Answer 1

to ensure rapid delivery of oxygen and nutrients and bring them close enough to cells for diffusion to take place

Question 2

Describe the pathway of circulation through the blood vessels in the body?

Answer 2

-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)

Question 3

What are the 2 types of artery?

Answer 3

elastic or muscular

Question 4

Artery-mean diameter, wall thickness and layers containing?

Answer 4

-4mm
-1mm
-endothelium
-elastic tissue
-smooth muscle
-fibrous tissue

Question 5

Arteriole-mean diameter, wall thickness and layers containing?

Answer 5

30 micro meteres
6 micro meteres
-endothelium
-smooth muscle

Question 6

Capillary-mean diameter, wall thickness and layers containing?

Answer 6

8 micrometeres
0.5 micrometres
-endothelium

Question 7

venule-mean diameter, wall thickness and layers containing?

Answer 7

20 micrometeres
1 micrometres
-endothelium
–fibrous tissue

Question 8

vein-mean diameter, wall thickness and layers containing?

Answer 8

5mm
0.5mm
-endothelium
-elastic tissue
-smooth muscle
-fibrous tissue

Question 9

What is the reservoir holding within the venous system of total blood when at rest?

Answer 9

65% of total blood

Question 10

Describe the structural characteristic of arteries and why they have this structure?

Answer 10

-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

Question 11

Describe the structural characteristic of capillaries and why they have this structure?

Answer 11

-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

Question 12

What are the 3 ways in which exchange takes place within capillaries?

Answer 12

-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)

Question 13

what is the movement of substances between endothelial cells within capillaries called?

Answer 13

paracellular pathway

Question 14

what is the movement of substances through endothelial cells within capillaries called?

Answer 14

transendothelial transport

Question 15

What are the 3 different types of capillaries called and what is the structure of each?

Answer 15

-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

Question 16

Describe the structural characteristic of veins and why they have this structure?

Answer 16

-carry blood back towards the heart
-Blood is low pressure so veins have thin walls and valves to help blood flow back to heart

Question 17

What are the 4 different layers that make up a blood vessel called?

Answer 17

-Lumen
-tunica intima
-tunica media
-tunica externa

Question 18

what is the lumen?

Answer 18

transport area
-a hollow passageway where blood flows

Question 19

what is the tunica intima and where is it in the blood vessels?

Answer 19

inner most layer
-arteries- endothelium, basement membrane & internal elastic lamina
-Veins- endothelium & basement membrane
-Capillaries- endothelium & internal elastic lamina

Question 20

What is the endothelium and what does it do?

Answer 20

made up of many endothelial cells- releases nitric oxide- allows for widening of a blood vessel to increase blood flow

Question 21

what is the tunica media and where is it in the blood vessels?

Answer 21

middle layer
(arteries-smooth muscle and elastic lamina)
(veins-smooth muscle)
-Important within role of vasodilation (making lumen bigger) and vasoconstriction (making lumen smaller)

Question 22

what is the tunica externa and where is it in the blood vessels?

Answer 22

outer layer
-in arteries & veins
-made up primarily of collagen fibres
-Role is to protect and reinforce vessel and anchor it to its surroundings

Question 23

What is the response of the blood vessels to acute exercise?

Answer 23

-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

Question 24

Describe the process of vasodilation?

Answer 24

-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

Question 25

Desricbe the process of vasoconstriction?

Answer 25

-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

Question 26

In response to exercise what features do the veins have in order to help blood flow back to heart?

Answer 26

-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