L8: Control of Blood Flow

Question 1

What happens to the blood flow after a large meal?

Answer 1

Increased blood flow to stomach & intestines

Question 2

What happens to blood flow at a localised inflammation?

Answer 2

Increased blood flow to affected areas only

Question 3

What happens to blood flow during diving?

Answer 3

Reduced blood flow to skeletal muscle, skin, kidneys, GI tract

Question 4

What happens to blood flow to brain & heart during diving?

Answer 4

Maintained

Question 5

What happens to the blood flow during aerobic exercise?

Answer 5

Increased blood flow to skeletal & cardiac muscle

Decreased blood flow to kidneys, GI tract

Question 6

What happens to blood flow to brain during aerobic exercise?

Answer 6

Maintained

Question 7

How can blood flow in some tissues be increased while at the same time others are decreased?

Answer 7

Different organs use different mechanisms or a combination of mechanisms for control of blood flow

Question 8

Equation for blood flow?

Answer 8

Flow = Pressure / Resistance

Question 9

What happens to resistance & blood flow during VASOCONSTRICTION?

Answer 9

Resistance INCREASED
Blood flow DECREASED

Question 10

What happens to resistance & blood flow during VASODILATION?

Answer 10

Resistance DECREASED
Blood flow INCREASED

Question 11

4 mechanisms for blood flow control

Answer 11

1) Sympathetic (neuronal) control
2) Endocrine control
3) Local metabolic control
4) Local myogenic vs metabolic control

Question 12

Tissues affected in sympathetic control

Answer 12

Muscle, skin, kidney, GI tract

Question 13

How are arterioles constricted at rest?

Answer 13

Partially constricted

Question 14

Mechnism of sympathetic control of blood flow

Answer 14

At rest, arterioles are partially constricted

MORE noradrenaline released-> arterioles constrict LESS-> REDUCED blood flow

LESS noradrenaline released -> arterioles construct LESS -> INCREASED blood flow

Question 15

Where are vasoactive hormones secreted into?

Answer 15

Blood

Question 16

Vasconstrictors in the hormonal control of blood flow

Answer 16

Angiotensin II (kidney)
Adrenaline (a-receptors)

Question 17

Vasodilators in the hormonal control of blood flow

Answer 17

ANP
Adrenaline (beta-receptors in muscle)

Question 18

What is active hyperaemia?

Answer 18

Increased blood flow

Question 19

What are blood flow controlled by?

Answer 19

Metabolites

Question 20

Define flow auto-regulation

Answer 20

When a tissue can regulate its own blood flow

Question 21

2 opposing mechanisms of flow auto-regulation

Answer 21

1) Metabolic Control
2) Myogenic control

Question 22

What is metabolic control in flow auto-regulation?

Answer 22

Dilates arterioles in response to metabolite accumulation

Question 23

What is myogenic control in flow auto-regulation?

Answer 23

Constricts arterioles in response to increased pressure

Question 24

What happens to muscle arterioles at rest?

Answer 24

Partially constricted by noradrenaline from sympathetic nerves

Question 25

What happens to sympathetic control when metabolic demand of the muscle increases?

Answer 25

Over-ridden by local metabolites & adrenaline, both causing vasodilation = 6 fold increase in blood flow = active hyperaemia

Question 26

Is adrenaline both a vasoconstrictor & vasodilator?

Answer 26

Yes

Question 27

What must happen to cardiac output to support increased blood flow to skeletal muscle?

Answer 27

Be doubled

Question 28

What happens to cardiac muscle & coronary blood flow when cardiac output is doubled?

Answer 28

Both doubled

Question 29

Why is blood supply more extensive in left ventricle than right?

Answer 29

Left ventricle is more thicker

Question 30

What happens when blood flow is during early DIASTOLE?

Answer 30

At its peak

Question 31

What happens when blood flow is during SYSTOLE?

Answer 31

Blood flows STOPS

Question 32

What is diastole?

Answer 32

Time between heart beats

Question 33

Does blood flow to the brain always have to remain constant?

Answer 33

Yes

Question 34

How is the blood flow staying constant in the brain achieved?

Answer 34

Flow Auto-regulation

Question 35

How does cerebral arterioles respond to changes in?

Answer 35

In perfusion pressure

Question 36

Define perfusion pressure

Answer 36

How much pressure it takes to push blood through all the blood vessels in a specific area

Question 37

What does increased CO & MAP increase?

Answer 37

Increase cerebral blood flow & cerebral perfusion pressure

Question 38

What is control of skin blood flow an essential component of?

Answer 38

Thermoregulation

Question 39

What are skin arterioles effectors in?

Answer 39

Thermoregulation Reflux

Question 40

What happens to skin arterioles at normal core body temp?

Answer 40

Partially constricted

Question 41

What nerves constrict skin arterioles that supply blood to the surface of the skin?

Answer 41

Sympathetic Nerves

Question 42

What detects changes in core temperature?

Answer 42

The Hypothalamus

Question 43

What reduces blood flow to the skin surface?

Answer 43

Constriction

Question 44

What increases blood flow to the skin surface?

Answer 44

Dilation

Question 45

What are the 2 types of circulation ?

Answer 45

Pulmonary & Systemic

Question 46

Are pulmonary & systemic circulation in series OR in parallel?

Answer 46

In series

Question 47

Equation for cardiac output for the right & left ventricle

Answer 47

RV CO = LV CO