Blood Flow

Question 1

What are the three factors that affect diffusion?

Answer 1

Area
Diffusion resistance
Concentration gradient

Question 2

Where is capillary density greatest?

Answer 2

Metabolically active tissues

Question 3

What factors contribute to the diffusion resistance?

Answer 3

Diffusion distance

Molecule size/charge/hydrophobicity/hydrophilicity

Question 4

At which end of a capillary is the diffusion rate greatest for metabolites used by tissues?

Answer 4

Arteriolar end (greatest concentration gradient)

Question 5

What affect does a loss of blood flow have on concentration gradient?

Answer 5

Causes the concentration gradient to dissipate

Question 6

What is the average cardiac output of a 75kg male at rest?

Answer 6

~5L/min

Question 7

How much can cardiac output increase by during exercise?

Answer 7

5x (~25L/min)

Question 8

What is the “perfusion rate”?

Answer 8

The rate of blood flow

Question 9

What are the blood flow requirements of the brain?

Answer 9

High, constant flow (0.5ml/min/g)

Question 10

What are the blood flow requirements of cardiac muscle?

Answer 10

High flow which increases with exercise (0.9-3.6ml/min/g)

Question 11

What are the blood flow requirements of the kidneys?

Answer 11

High, constant flow (3.5ml/min/g)

Question 12

What is the function of arterioles?

Answer 12

Resistance vessels to regulate blood flow - increasing flow resistance to some areas increases perfusion to more difficult to perfume areas (e.g brain vs gravity)

Question 13

What mechanism allows for total flow to change?

Answer 13

Venous capacitance - acts as a reservoir

Question 14

Where is blood distributed to each of the following areas approximately?
Arteries and arterioles
Capillaries
Heart and lungs
Veins

Answer 14

Veins - 65% 3.9L
Heart and lungs - 20% 1.2L
Arteries and arterioles - 10% 0.6L
Capillaries - 5% 0.3L