Lecture 11: CONTROLLING REGIONAL BLOOD FLOWS

Question 1

What does low pressure mean?

Answer 1

Lack of control of flow

Question 2

What does high pressure mean?

Answer 2

Full control of flow

Question 3

Why must high mean arterial pressure be maintained?

Answer 3

For full control over blood flow

Question 4

What is the design of the systemic circulation?

Answer 4

Parallel

Question 5

How is the arterial network in the systemic circulation?

Answer 5

Continually branching

Question 6

What does the branching in the systemic circulation do?

Answer 6

Divides blood flow among the regional (organ) circulations

Question 7

What does each organ receive?

Answer 7

An individual flow of blood which may be different to the flow of another organ

Question 8

What is flow into an organ the same as?

Answer 8

The flow out of an organ

Question 9

What is the total flow equal to?

Answer 9

All of the flows into individual organs added together

Question 10

The total flow into the pulmonary and systemic circuits is …

Answer 10

the same

Question 11

Where does blood flow to increase during exercise?

Answer 11

Muscle, heart and skin (so that heat can be lost)

Question 12

Where does blood flow to decrease during exercise?

Answer 12

GI tract and kidneys

Question 13

Where does blood flow to stay the same during exercise?

Answer 13

Brain

Question 14

What does the diverging blood flow depend on?

Answer 14

The metabolic needs of the region/organ at that time

Question 15

How is MAP controlled during exercise?

Answer 15

Cardiac output increases and so total peripheral resistance must decrease so that MAP is maintained

Question 16

How does resistance to muscle, heart and skin change during exercise?

Answer 16

It decreases so that the blood flow is able to increase

Question 17

How does resistance to the kidneys and GI tract change during exercise?

Answer 17

It increases so that blood flow is able to decrease

Question 18

What is control of organ resistance and regional flow done by?

Answer 18

The resistance vessels - arterioles

Question 19

What does a large radius mean?

Answer 19

Low resistance

Question 20

What does a small radius mean?

Answer 20

High resistance

Question 21

What is the rule of 16?

Answer 21

If the lumen changes by a factor of 2, the resistance will change by a factor of 16

Question 22

What is blood flow to an organ or region controlled by?

Answer 22

Adjusting arteriolar (vascular) tone and radius

Question 23

What does decreasing radius mean?

Answer 23

Smooth muscle contracts and the blood vessel vasoconstricts so there is less blood flow to the regions/organs

Question 24

What does increasing radius mean?

Answer 24

Smooth muscle relaxes and the blood vessel vasodilator so there is more blood flow to the regions/organs

Question 25

What is vasodilation and vasoconstriction used for?

Answer 25

To direct cardiac output