7.6 blood vessels

Question 1

what does the muscle layer do?

Answer 1

contract & control blood flow

Question 2

what does the elastic layer do?

Answer 2

maintain pressure by stretching & recoiling

Question 3

what does the outer layer do?

Answer 3

• tough & fibrous
• resist pressure changes within & without

Question 4

what is the lumen?

Answer 4

central cavity

Question 5

what is the role of the artery?

Answer 5

transport blood from the heart -> arteriole

Question 6

describe & explain the 6 structures in the artery.

Answer 6

1- muscle layer
- thick - to control blood flow by constriction & dilation

2- elastic layer
- thick to maintain high blood pressure (to get blood to extremities)
- smooths pressure surges

3- outer layer
- thick to prevent bursting from pressure

4- lumen
- narrow for higher pressure

5- valves
n/a

6- blood pressure
- high

Question 7

describe & explain the 6 structures in the arteriole.

Answer 7

1- muscle layer
- thicker to control blood flow by constriction & restrict blood flow into capillaries

2- elastic layer
- thinner -> lower pressure

3- outer layer
- thinner -> lower pressure

4- lumen
- narrow (variable)

5- valves
n/a

6- blood pressure
lower than arteries

Question 8

describe and explain the 6 structures of the vein.

Answer 8

1- muscle layer
- thin as it can’t control blood flow to tissues

2- elastic layer
- thinner -> lower pressure & can’t recoil

3- outer layer
- thinner -> lower pressure & no risk of bursting

4- lumen
- wide

5- valves
present

6- blood pressure
lower than arteries

Question 9

describe & explain the 6 structures of capillaries.

Answer 9

1- muscle layer
n/a

2- elastic layer
n/a

3- outer layer
- consists of endothelium, 1 cells thick only for rapid diffusion

4- lumen
- very narrow (squeezes red blood cell against the wall for low diffusion distance)

5- valves
n/a

6- blood pressure
very low for more time for exchanging materials

Question 10

how is tissue fluid formed?

Answer 10

blood plasma leaking out of capillaries

Question 11

explain how tissue fluid is formed & how it is returned to the circulatory system. (6)

Answer 11

1- higher hydrostatic blood pressure at arterial end

2- fluid / H2O / soluble molecules pass out

3- proteins & large molecules remain

4- this lowers water potential

5- H2O moves back into venous end of capillary by osmosis

6- lymph system collects extra tissue fluid & returns back to blood