Cardiovascular Physiology II

Question 1

What is necessary to have flow in a vascular system?

Answer 1

A pressure gradient is required; flow occurs from an area of higher pressure to an area of lower pressure.

Question 2

What equation represents the relationship among pressure, flow, and resistance?

Answer 2

Flow = Pressure Gradient / Resistance

Question 3

What happens to flow when resistance increases, assuming pressure remains constant?

Answer 3

Flow decreases as resistance increases.

Question 4

What factors determine resistance in a tube (e.g., blood vessels)?

Answer 4

Resistance = (8 × viscosity × length) / (π × radius^4)

Question 5

How does shortening a tube affect flow and resistance?

Answer 5

Shortening the tube decreases resistance, making it easier to maintain flow.

Question 6

What effect does narrowing a tube have on flow?

Answer 6

Narrowing a tube increases resistance, making it harder to maintain the same level of flow.

Question 7

How does viscosity affect the ease of flow through a tube?

Answer 7

Higher viscosity (like a milkshake) makes flow more difficult compared to lower viscosity (like soda).

Question 8

Which factor has the greatest impact on regulating blood flow in the body?

Answer 8

The radius of the blood vessel; small changes in radius lead to significant changes in resistance.

Question 9

How does vessel radius relate to resistance?

Answer 9

Resistance is inversely related to the fourth power of the radius, meaning small changes in radius can lead to large changes in resistance.

Question 10

Can the length of blood vessels change acutely?

Answer 10

No, the length of blood vessels does not change acutely; they are structured to be as long as needed.

Question 11

Under what circumstances can blood viscosity change significantly?

Answer 11

Blood viscosity can change in disease processes or in cases like blood doping, which can lead to cardiovascular events.

Question 12

What primarily regulates blood flow distribution in the vascular system?

Answer 12

The diameter of the arterioles.

Question 13

What are the two broad categories of mechanisms that change the diameter of arterioles?

Answer 13

Local mechanisms and distant mechanisms.

Question 14

What are three examples of local mechanisms that affect arterioles?

Answer 14

1. Tissue metabolites (leading to dilation)
2. Myogenic response
3. Endothelial factors

Question 15

What is “active hyperemia”?

Answer 15

The increase in blood flow resulting from increased metabolic activity in a tissue.

Question 16

What is “reactive hyperemia”?

Answer 16

The increase in blood flow following a temporary restriction of blood flow.

Question 17

How do tissue metabolites affect arterioles during active hyperemia?

Answer 17

Increased metabolic activity releases metabolites that cause arterioles to dilate.

Question 18

What role do endothelial cells play in regulating blood flow?

Answer 18

Endothelial cells release vasoactive substances in response to shear stress from blood flow, contributing to vasodilation.

Question 19

What is “myogenic control” in relation to blood flow?

Answer 19

The ability of arterioles to respond to changes in blood pressure by dilating or constricting to maintain constant blood flow.

Question 20

What is the baroreceptor reflex?

Answer 20

A rapid reflex that maintains blood pressure by adjusting heart rate and vascular resistance in response to changes in arterial blood pressure.

Question 21

How does the sympathetic nervous system affect blood pressure during the baroreceptor reflex?

Answer 21

It increases cardiac output and total peripheral resistance to raise blood pressure when it decreases.

Question 22

What is the renin-angiotensin-aldosterone system’s role in blood pressure regulation?

Answer 22

It increases blood pressure through mechanisms such as vasoconstriction, sodium reabsorption, and fluid retention.

Question 23

How can pharmacological agents help manage high blood pressure?

Answer 23

By decreasing cardiac output (e.g., beta blockers), reducing total peripheral resistance (e.g., ACE inhibitors), or decreasing fluid volume (e.g., diuretics).

Question 24

What are the components of mean arterial pressure?

Answer 24

Cardiac output and total peripheral resistance.

Question 25

Why is the production of vasodilator metabolites important during exercise?

Answer 25

It facilitates the increase in blood flow to meet the heightened metabolic demands of active tissues.

Question 26

What happens to cardiac output during exercise?

Answer 26

Cardiac output increases due to an increase in heart rate and stroke volume.

Question 27

How is blood flow redistributed during exercise?

Answer 27

More blood flow is directed to active skeletal muscle, while less blood flow goes to other organs.

Question 28

What is the effect of sympathetic nervous system activation on blood flow to the viscera?

Answer 28

The sympathetic nervous system causes vasoconstriction of the blood vessels feeding the viscera, leading to decreased blood flow.

Question 29

How do active muscles receive increased blood flow despite sympathetic vasoconstriction?

Answer 29

Increased blood flow to active muscles is driven by local metabolic signals that induce vasodilation, counteracting the vasoconstrictor effect.

Question 30

What is active hyperemia?

Answer 30

The increase in blood flow due to increased metabolic activity of the tissue.

Question 31

What is reactive hyperemia?

Answer 31

The increase in blood flow following a temporary restriction of blood flow.

Question 32

What contributes to the widening of the arterial-venous (a-v) oxygen difference during exercise?

Answer 32

The drop in venous oxygen content due to increased oxygen consumption by the muscles and blood shunting from less active tissues.

Question 33

How does arterial oxygen content change during intense exercise?

Answer 33

Arterial oxygen content generally remains stable during peak exercise in most individuals.

Question 34

What changes occur in blood pressure during exercise?

Answer 34

Mean arterial pressure increases modestly, diastolic blood pressure may remain constant or decrease, and systolic blood pressure increases linearly with workload.

Question 35

What indicates a potential problem if systolic blood pressure falls during exercise?

Answer 35

A falling systolic blood pressure during increasing workload suggests possible ischemia or heart problems.