Cardiovascular Physiology 31

Question 1

What pressure drives blood flow to all the organs and tissues (except the lungs) in the average cardiac cycle?

Answer 1

The mean arterial pressure (MAP)

Question 2

What is the prerequisite for ensuring adequate blood flow to all organs and tissues?

Answer 2

Maintaining MAP

Question 3

What would happen if blood pressure were to decrease significantly?

Answer 3

The tissues of the body would quickly die as the would not receive significant oxygen and metabolites would build up

Question 4

What are the consequences of chronically high blood pressure?

Answer 4

Damage to the arteries, heart and kidneys

Question 5

How can MAP be calculated in relation to CO and TPR?

Answer 5

MAP = CO x TPR

Question 6

What does MAP depend on?

Answer 6

The cardiac output (CO) and the total peripheral resistance (TPR)

Question 7

What alters MAP?

Answer 7

Cardiac output and total peripheral resistance

Question 8

What is total peripheral resistance?

Answer 8

The combined resistance to flow of all the systemic blood vessels

Question 9

Why doesn’t the pulmonary circulation provide a lot of resistance to flow?

Answer 9

Because the vessels are very short, do not contain much smooth muscle and are not as numerous compared to those in the systemic circulation

Question 10

What produces resistance in blood vessels?

Answer 10

Friction between the blood and the walls of the blood vessels

Question 11

Where is the major site of resistance in the system circulation?

Answer 11

The arterioles

Question 12

What are changes in TPR due mostly to?

Answer 12

Changes in the resistance of the arterioles. ex contraction of the smooth muscle in the walls of the arterioles

Question 13

What is TPR primarily determined by?

Answer 13

Total arteriolar resistance

Question 14

What allows arterioles to change their diameter?

Answer 14

The smooth muscle in their vessel walls

Question 15

Why is the pressure drop through arterioles great?

Answer 15

Because blood experiences a lot of resistance to flow in them

Question 16

What are the types of controls that can affect TPR?

Answer 16

• Local controls
• Neural controls
• Hormonal controls

Question 17

What do the controls that affect TPR do?

Answer 17

Cause vasodilation or vasoconstriction

Question 18

What will any change in arterial pressure elicit?

Answer 18

Homeostatic mechanisms

Question 19

What two types of mechanisms are used to regulate the MAP?

Answer 19

• Short-term regulation

* Long-term regulation

Question 20

How long do short term adjustments of MAP last?

Answer 20

Seconds to hours

Question 21

What are short-term regulation of MAP brought about by?

Answer 21

Baroreceptor reflexes

Question 22

What do Baroreceptor Reflexes do?

Answer 22

Modify the activity of autonomic nerves supplying the heart and blood vessels and changes in the secretion of hormones like epinephrine

Question 23

What are the long-term regulations of MAP?

Answer 23

Adjusts in blood volume and normal salt and water balance through mechanisms that require urine output and thirst

Question 24

What kind of receptors are Arterial Baroreceptors?

Answer 24

Mechanoreceptors

Question 25

What do Arterial Baroreceptors detect?

Answer 25

Changes in the blood pressure

Question 26

Where are the Baroreceptors found?

Answer 26

In the carotid sinus and the aortic arch

Question 27

What is the wall of the artery like a baroreceptors?

Answer 27

Thinner than usual and has a large number of branching sensory neuronal processes

Question 28

What changes do the Arterial Baroreceptors response to?

Answer 28

Changes in MAP and changes in pulse pressure

Question 29

When do the Arterial Baroreceptors respond to changes in pressure?

Answer 29

When the walls of the vessel stretch and relax

Question 30

What is the degree of wall stretching proportional to?

Answer 30

The pressure within the artery

Question 31

What is the Pulse pressure?

Answer 31

The difference between the systolic and diastolic pressures

Question 32

What is the rate of discharge of a baroreceptor proportional to?

Answer 32

The MAP

Question 33

How is the rate of discharge of the baroreceptor affected by an increase in MAP?

Answer 33

The baroreceptor increases the frequency with which it fires

Question 34

What does the rate of the Baroreceptor action potential flucuate with?

Answer 34

Changes in pressure

Question 35

How is the firing rate of baroreceptors affected by a decrease in pressure?

Answer 35

The baroreceptor has a decreased firing rate

Question 36

What is the primary integrating center for the baroreceptor reflexes?

Answer 36

The medullary cardiovascular center in the medulla oblongata

Question 37

What do the inputs that the medullary cardiovascular center receives from baroreceptors determine?

Answer 37

The frequency of action potential sent from the center to neural pathways that terminate on the cell bodies of neurons of the vagus or parasympathetic neurons to the heart or sympathetic neurons to the heart, arterioles and veins

Question 38

What does an increase in firing by the arterial baroreceptors signal the medullary cardiovascular center to do?

Answer 38

Decrease the sympathetic activity to the heart, arterioles and veins and increase parasympathetic activity to the heart decreases arterial pressure

Question 39

What do Baroreceptors adapt to?

Answer 39

Sustained changes in arterial pressure

Question 40

Why are Baroreceptors only used in short term regulation of blood pressure?

Answer 40

Because they adapt to sustained changes in blood pressure

Question 41

What mechanisms does the long term regulation of arterial blood pressure require?

Answer 41

Hormonal and Renal mechanisms