Regulation of Arteriolar Resistance

Question 1

What does Darcy’s Law state?

Answer 1

Flow = ∆Pressure / resistance

Question 2

The radius of resistance vessels is used to control flow and redirect blood, it is also used to

Answer 2

control total peripheral resistance (TPR) and regulate mean arterial pressure (MAP)

Question 3

Arteriolar radius affects flow through individual

Answer 3

vascular beds and mean arterial pressure

Question 4

What two mechanisms are used to keep blood flow to each vascular bed and MAP in the right range?

Answer 4

Intrinsic and extrinsic mechanisms

Question 5

Intrinsic mechanisms control

Answer 5

the needs of each individual tissue

Question 6

Extrinsic mechanisms ensure

Answer 6

total peripheral resistance of the whole body stays within the right range

Question 7

What nerves are involved in extrinsic mechanisms?

Answer 7

Sympathetic

Question 8

What is released by sympathetic nerves in extrinsic mechanisms?

Answer 8

Noradrenaline

Question 9

What effect does noradrenaline have on arterioles?

Answer 9

Causes arteriolar constriction

Question 10

What receptors does noradrenaline bind to?

Answer 10

Alpha-1

Question 11

What effect does arteriolar constriction have on blood flow through tissues and TPR?

Answer 11

• decreases flow through that tissue

- tends to increase TPR

Question 12

What hormone is involved in extrinsic control?

Answer 12

Adrenaline

Question 13

From where is adrenaline released?

Answer 13

Adrenal medulla

Question 14

What receptors does adrenaline bind to?

Answer 14

Alpha-1

Beta-2 in skeletal and cardiac muscle

Question 15

What effect does adrenaline have on arterioles when it binds to alpha-1 receptors?

Answer 15

Causes arteriolar constriction

Question 16

What effect does adrenaline have on arterioles when it binds to Beta-2 receptors?

Answer 16

Causes arteriolar dilation

Question 17

Other than adrenaline, what hormones are released to control extrinsic mechanisms?

Answer 17

• angiotensin II
• vasopressin
• atrial natriuretic peptide
• brain natriuretic peptide

Question 18

What hormones are released in response to high blood volume?

Answer 18

• atrial natriuretic peptide

- brain natriuretic peptide

Question 19

What hormones are produced/released in response to low blood volume?

Answer 19

• angiotensin II

- vasopressin

Question 20

What hormones produced in the control of extrinsic mechanisms cause arteriolar constriction and increase TPR?

Answer 20

• angiotensin II

- vasopressin

Question 21

What hormones produced in the control of extrinsic mechanisms cause arteriolar dilation and decrease TPR

Answer 21

• atrial natriuretic peptide

- brain natriuretic peptide

Question 22

What are the 4 mechanisms involved in intrinsic control?

Answer 22

• active (metabolic) hyperaemia
• pressure (flow) autoregulation
• reactive hyperaemia
• the injury response

Question 23

What effects does active hyperaemia have on

• metabolic activity
• arterioles
• blood flow?

Answer 23

• metabolic activity increases
• arterioles dilate
• blood flow increases

Question 24

Active hyperaemia matches blood supply to

Answer 24

the metabolic needs of the tissue

Question 25

What effects does pressure autoregulation have on - mean arterial pressure - arterioles - blood flow?

Answer 25

- MAP decreases - arterioles dilate - blood flow decreases

Question 26

Pressure autoregulation ensures that a tissue maintains its blood supply despite

Answer 26

changes in MAP

Question 27

What is reactive hyperaemia?

Answer 27

The occlusion of blood supply causing a subsequent increase in blood flow

Question 28

What does the injury response do?

Answer 28

Aids the delivery of blood borne immune cells to the injured area

Question 29

In coronary circulation, blood supply is interrupted by

Answer 29

systole

Question 30

When does the coronary circulation have to cope with increased demand?

Answer 30

During exercise

Question 31

What receptors are expressed by the coronary circulation?

Answer 31

Many Beta-2 receptors

Question 32

What method of intrinsic control is shown in coronary circulation?

Answer 32

Active hyperaemia

Question 33

Beta-2 receptors and active hyperaemia in the coronary circulation negate what in the arterioles?

Answer 33

Sympathetic arteriolar constriction

Question 34

Cerebral circulation needs to be kept

Answer 34

stable

Question 35

What method of intrinsic control is seen in the cerebral circulation?

Answer 35

Pressure autoregulation

Question 36

In pulmonary circulation, decreased oxygen causes

Answer 36

arteriolar constriction

Question 37

Arteriolar constriction in the pulmonary circulation ensures that

Answer 37

blood is directed to the best ventilated parts of the lung

Question 38

What is the main function of renal circulation?

Answer 38

Filtration

Question 39

What changes would have big effects on blood volume in the renal circulation?

Answer 39

Changes in MAP

Question 40

What method of intrinsic control is shown in the renal circulation?

Answer 40

Pressure autoregulation