Spring 2024 Exam 1 lang qs

Question 1

Which of the following would increase blood flow through a skeletal muscle?
a. an increase in tissue P CO2
b. an increase in tissue adenosine
c. the presence of α-receptor-blocking drugs d. sympathetic activation

Answer 1

The correct answers are a, b, and c.

Question 2

Autoregulation of blood flow implies that arterial pressure is adjusted by local mechanisms to ensure constant flow through an organ. True or false?

Answer 2

False. Autoregulation of blood flow implies that vascular resistance is adjusted to maintain constant flow in spite of changes in arterial pressure.

Question 3

Coronary blood flow will normally increase when
a. arterial pressure increases .
b. the heart rate increases .
c. sympathetic activity increases .

Answer 3

All, because they all increase myocardial oxygen consumption. Myocardial blood flow is controlled primarily by local metabolic mechanisms.

Question 4

The arterioles of skeletal muscle would have little or no tone in the absence of normal sympathetic vasoconstrictor fiber activity. True or false?

Answer 4

False. Sympathectomy will cause some dilation of skeletal muscle arterioles but not a maximal dilation because skeletal muscle arterioles have a strong inherent basal tone.

Question 5

A person who hyperventilates (breathes rapidly and deeply) gets dizzy. Why?

Answer 5

Hyperventilation decreases the blood P CO 2 level. This, in turn, causes cerebral arterioles to constrict (recall that cerebral vascular
tone is highly sensitive to changes in P CO 2). The increased cerebral vascular resistance causes a decrease in cerebral blood
flow, which produces dizziness and disorientation.

Question 6

A patient complains of severe leg pains after walking a short distance. The pains disappear after the patient rests. (This symptom is called intermittent claudication.) What might be the problem?

Answer 6

It is likely that the increased metabolic demands evoked by the exercising skeletal muscle cannot be met by an appropriate increase in blood flow to the muscle. This patient may have some sort of arterial disease (atherosclerosis) that provides a high resistance to flow that cannot be overcome by local metabolic vasodilator mechanisms.

Question 7

How would a stenotic aortic valve influence coronary blood flow?

Answer 7

High left ventricular pressures must be developed to eject blood through the stenotic valve ( Figure 5–4A). This increases myocardial oxygen consumption, which tends to increase coronary flow. At the same time, however, high intraventricular pressure development enhances the systolic compression of coronary vessels and tends to decrease flow. The local metabolic mechanisms may be adequate to compensate for the increased compressional forces and meet the increased myocardial metabolic needs in a resting individual. However, there may not be enough “reserve” to meet additional needs such as those that accompany exercise. Coronary perfusion pressure may also be decreased if the systemic arterial pressure is lower than normal.

Question 8

Vascular smooth muscle differs from cardiac muscle in that it
a. contains no actin molecules .
b. can be directly activated in the absence of action potentials .
c. is unresponsive to changes in intracellular calcium levels .
d. is unresponsive to changes in membrane potentials .
e. is unresponsive to changes in muscle length .

Answer 8

b

Question 9

Arteriolar constriction tends to do which of the following?
a. decrease total peripheral resistance
b. decrease mean arterial pressure
c. decrease capillary hydrostatic pressure
d. increase transcapillary fluid filtration
e. increase blood flow through the capillary bed

Answer 9

c

Question 10

When an organ responds to an increase in metabolic activity with a decrease in its arteriolar resistance, this is known as
a. active hyperemia
b. reactive hyperemia
c. autoregulation of blood flow
d. flow-dependent vasodilation
e. metabolic vasoconstriction

Answer 10

a

Question 11

In which of the following organs does decreased P O 2 cause arteriolar vasoconstriction?
a. lungs
b. skin
c. skeletal muscle d. brain
e. none of the above

Answer 11

a. Hypoxic arteriolar vasoconstriction is a phenomenon that is known to occur only in the lungs.

Question 12

Coronary blood flow occurs largely during diastole. True or false?

Answer 12

True. During systole, coronary vessels are collapsed by external compression forces.

Question 13

Which of the following conditions favor edema formation?
a. lymphatic blockage
b. thrombophlebitis (venous clot)
c. decreased plasma protein concentration
d. greatly increased capillary pore size

Answer 13

All do: a and d, by allowing interstitial protein buildup; b, by raising P c; and c for decreasing plasma oncotic pressure.

Question 14

Answer 14

Question 15

TPR is always greater than the resistance to flow through any of the systemic organs. True or false?

Answer 15

False. TPR is less than the resistance to flow through any of the organs. Each organ, in effect, provides an additional pathway through which blood may flow. Thus, the individual organ resistances must be greater than the total resistance and

Question 16

If the resistance to flow through the kidneys increases and the resistance to flow through other systemic organs remains constant, TPR will increase. True or false?

Answer 16

true

Question 17

Chronic elevation of arterial pressure requires that either cardiac output or TPR (or both) be chronically elevated. True or false?

Answer 17

Question 18

Constriction of arterioles in an organ promotes reabsorption of interstitial fluid from that organ. True or false?

Answer 18

True. Because arteriolar constriction tends to reduce the hydrostatic pressure in the capillaries, reabsorptive forces will exceed filtration forces and net reabsorption of interstitial fluid into the vascular bed will occur.

Question 19

Acute rapid increases in arterial pulse pressure usually result from increases in stroke volume. True or false?

Answer 19

Question 20

Whenever cardiac output is increased, mean arterial pressure must also be increased. True or false?

Answer 20

False. Increases in cardiac output are often accompanied by decreases in total peripheral resistance. Depending on the relative magnitude of these changes, mean arterial pressure could rise, fall, or remain constant.

Question 21

Answer 21

Question 22

At rest the patient has a pulse rate of 70 beats/min and an arterial blood pressure of 119/80 mm Hg. During exercise on a treadmill, pulse rate is 140 beats/min and blood pressure is 135/90 mm Hg. Use this information to estimate the exercise-related changes in the following variables:
stroke volume
cardiac output
total peripheral resistance (TPR)

Answer 22

Question 23

Answer 23

d

Question 24

Question 25

Massage of the neck over the carotid sinus area in a person experiencing a bout of paroxysmal atrial tachycardia is often effective in terminating the episode. Why?

Answer 25

Carotid sinus massage causes arterial baroreceptors to fire, which in turn increases parasympathetic activity from the medullary cardiovascular centers. This can either slow the pacemaker activity or interrupt a reentry tachycardia and allow a more normal rhythm to be established.

Question 26

Answer 26

a, b, and d would increase sympathetic nerve activity; c and e would decrease it.

Question 27

Describe the immediate direct and reflex cardiovascular
consequences of giving a healthy person a drug that blocks α 1- adrenergic receptors. Describe the possible changes in mean arterial pressure, sympathetic nerve activity, cardiac output, total peripheral resistance, and shifts in the cardiac function and venous return curves.

Answer 27

Step 1. The influence of sympathetic nerve activity on arteriolar tone will be blocked. Arteriolar tone will fall and so will TPR. This will directly lower mean arterial pressure.
Step 2. The arterial baroreceptor firing rate will decrease, which will increase sympathetic nerve activity from the medullary CV centers.
Step 3. The heart rate and cardiac output will reflexly increase because of the cardiac effects of the increased sympathetic activity on β 1-adrenergic receptors. Total peripheral resistance will not be
improved by the increase in sympathetic drive because the drug has blocked the α 1-adrenergic receptors.
Step 4. The cardiac function curve will shift upward, but the venous return curve will not shift, because the α-receptor blockade blocks the effect of increased sympathetic activity on the veins. Consequently, central venous pressure will be lower than normal (see Figure 8–6).

Question 28

What net short-term alterations in mean arterial pressure and sympathetic activity would the following produce?
a. blood loss through hemorrhage
b. cutaneous pain
c. systemic hypoxia
d. local metabolic vasodilation in the skeletal muscle

Answer 28

a and d are primary disturbances to the cardiovascular system. These will directly reduce the mean arterial pressure. Reflex adjustments largely mediated by the arterial baroreceptors will result in a higher-than-normal sympathetic activity.

b and c elicit set point–increasing inputs to the medullary cardiovascular system that result in a higher-than-normal sympathetic output for any given level of input from the arterial baroreceptors. Thus, in the presence of these disturbances, the system will operate at higher-than-normal mean arterial pressure and sympathetic activity.

Question 29

Your patient has lower-than-normal mean arterial pressure and higher-than-normal pulse rate. Which of the following are possible diagnoses?
a. low blood volume
b. anxiety
c. a cardiac valve problem
d. elevated intracranial pressure

Answer 29

a and c. These disturbances would tend to directly lower blood pressure, which would then lead to a reflex increase in the heart rate. Disturbances b and d have no direct effect on the heart or vessels. Rather they act on the medullary cardiovascular centers to raise the set point and cause an increase in sympathetic activity. Consequently, one would expect b (and d in early phases) to cause increases in both the heart rate and the mean arterial pressure. In the case of prolonged and severely elevated intracranial pressure, the increased sympathetic activity does indeed raise arterial pressure to very high levels, but the arterial baroreceptors can fight this by simultaneously increasing parasympathetic drive to decrease the heart rate (second phase of Cushing reflex).

Question 30

In the normal operation of the arterial baroreceptor reflex, a cardiovascular disturbance that lowers mean arterial pressure will evoke a decrease in
a. baroreceptor firing rate
b. sympathetic nerve activity
c. heart rate
d. total peripheral resistance
e. myocardial contractility

Answer 30

a

Question 31

Answer 31

c

Question 32

If your patient’s mean systemic arterial pressure changes, it must be because of changes in
a. the heart rate and/or myocardial contractility
b. cardiac output and/or total peripheral resistance
c. blood volume and/or venous tone
d. sympathetic and/or parasympathetic nerve activity
e. arterial compliance and/or stroke volume

Answer 32

b

Question 33

You hear a systolic murmur that seems to be coming from the right side of the heart.
a. Which valve condition(s) might be the cause of this abnormal sound?
b. A finding of a right electrical axis deviation might support which of your possible diagnoses?
c. Would you expect your patient to have pulmonary congestion?

Answer 33

Question 34

Answer 34

a and b, because filling time is reduced; c, if ventricular rate is rapid; d, for obvious reasons; but not e, because ventricular pacemakers produce a lower heart rate, which is associated with a longer filling time and therefore, a larger stroke volume.

Question 35

You notice an abnormally large pulsation of your patient’s jugular vein, which occurs at about the same time as heart sound, S 1 . What is your diagnosis?

Answer 35

Tricuspid insufficiency. With proper positioning of the patient, pulsations in the neck veins can be observed. Regurgitant flow of blood through a leaky tricuspid valve during systole produces this large abnormal wave.

Question 36

Describe the primary pressure abnormalities across the cardiac valve that are associated with
a. aortic stenosis b. mitral stenosis

Answer 36

Aortic stenosis produces a significant pressure difference between the left ventricle and the aorta during systolic ejection (a time when this valve normally should be widely open and create little resistance to flow).

Mitral stenosis produces a significant pressure difference between the left atrium and the left ventricle during diastole (a time when this valve normally should be widely open)

Question 37

What alteration in jugular venous pulsations might accompany third-degree heart block?

Answer 37

Irregular giant a waves (called cannon waves) are observed in the jugular veins whenever the atrium contracts against a closed tricuspid valve (i.e., during ventricular systole). Because in third- degree heart block the atria and ventricles are beating independently, this situation may occur at irregular intervals.

Question 38

Your 75-year-old male patient is alert with complaints of general fatigue. His heart rate = 90 beats/min and arterial pressure = 180/50 mm Hg. A diastolic murmur is present. There are no ECG abnormalities identified and mean electrical axis = 10 degrees. Cardiac catheterization indicates that LV pressure = 180/20 mm Hg and left atrial pressure = 10/3 mm Hg (as peak systolic/end- diastolic). What abnormality is most consistent with these findings?

Answer 38

Aortic insufficiency.

Question 39

Evaluation of your patient’s electrocardiogram shows that P waves occur at a regular rate of 90/min and QRS complexes occur at a regular rate of 37/min. Which of the following is the most likely diagnosis?
a. supraventricular tachycardia
b. first-degree heart block
c. second-degree heart block
d. third-degree heart block
e. bundle branch block

Answer 39

d. The total dissociation of atrial and ventricular rates indicates lack of AV communication.

Question 40

An otherwise healthy, vigorous 74-year-old woman comes to your office with complaints of having recent episodes of intermittent dizziness and weakness associated with a feeling of fluttering and/or pounding in her chest. Her blood pressure is 135/88 mm Hg and her overall pulse rate is about 80 beats per minute with an irregularly irregular rhythm (i.e., no discernable pattern). What is the most likely diagnosis? What will you do next?

Answer 40

Although atrial fibrillation is the most likely diagnosis, without ECG validation, paroxysmal supraventricular tachycardia, atrial flutter, AV nodal block, and even ventricular flutter cannot be ruled out. Subsequent steps should include chronic cardiac monitoring over a week or more (Holter monitor), followed by pharmacological interventions to subdue the arrhythmia and, if atrial fibrillation, an anticoagulant to suppress clot formation in the atria and potential stroke.

Question 41

If pulmonary artery pressure is 24/8 mm Hg (systolic/diastolic), what are the respective systolic and diastolic pressures of the right ventricle?

Answer 41

The ventricular systolic pressure is also 24 mm Hg because the normal pulmonic valve provides negligible resistance to flow during ejection. The right ventricular diastolic pressure, however, cannot be determined from the pulmonary artery pressure. It is determined by systemic venous pressure and normally will be close to 0 mm Hg.

Question 42

Which of the following interventions will increase cardiac stroke volume?
a. increased ventricular filling pressure
b. decreased arterial pressure
c. increased activity of cardiac sympathetic nerves
d. increased circulating catecholamine levels

Answer 42

All of them are correct answers: a, by increasing preload; b, by decreasing afterload; and c and d by augmenting contractility

Question 43

In which direction will cardiac output change if central venous pressure is lowered while cardiac sympathetic tone is increased?

Answer 43

One cannot tell from the information given because the two alterations would have opposite effects on cardiac output (i.e., although decreased filling will reduce stroke volume, increased sympathetic tone will increase both stroke volume and heart rate). A complete set of ventricular function curves, as well as quantitative information about the changes in filling pressure and sympathetic tone, would be necessary to answer the question. (See Figure 3–8.)

Question 44

Increases in sympathetic neural activity to the heart will result in an increase in stroke volume by causing a decrease in end-systolic volume for any given end-diastolic volume. True or false?

Answer 44

True. (See Figure 3–6.) Increased sympathetic activity will increase contractility and ejection fraction.

Question 45

Four of these conditions exist during the same phase of the cardiac cycle and one does not. Which one is the odd one?
a. The mitral valve is open.
b. The ST segment of the ECG is occurring.
c. Ventricular volume is increasing.
d. Aortic pressure is falling.

Answer 45

b, because the ST segment of the ECG occurs during systole, whereas all the other events occur during diastole.

Question 46

Answer 46

a, because the isovolumic contraction phase is the most energetically costly part of the cardiac cycle and increases in heart rate multiply this effect. Note, increases in end-diastolic volume (choice c) will also increase myocardial oxygen demands (because wall tension is proportional to pressure and radius, T ∼ Pr) but to a much lesser extent than do increases in heart rate.

Question 47

Answer 47

b, because sympathetic activation will increase action potential conduction through the AV node and thereby decrease the PR interval. All of the other choices will be increased by activation of cardiac sympathetic nerves. (The increase in metabolic demands will increase coronary blood flow by mechanisms described in more detail in Chapter 7.)

Question 48

An increase in total peripheral resistance (TPR) normally results in an increase in the external work rate required by the heart. True or false?

Answer 48

False. Recall that changes in TPR are caused by peripheral
vascular responses and that the heart normally responds by adjustments in its cardiac output so as to keep arterial pressure constant. At constant arterial pressure, an increase in TPR implies a reduction in CO. According to the cardiac external work rate equation (WR = MAP × CO), a decrease in CO at constant MAP will cause a decrease in the work rate of the heart. This is the main reason that your heart is working less hard when you are at rest than when you are exercising.

Question 49

The metabolic requirement of the heart muscle in any situation is always equal to how much external work the heart is doing in that situation. True or false?

Answer 49

False. Whereas basic thermodynamics says that to produce any given amount of external work, the heart must expend at least an equal amount of chemical energy. But the heart muscle is only about 30% efficient in converting chemical energy into mechanical work. Thus for openers, to produce any given external work, the heart consumes roughly 3 times that amount of chemical energy. Moreover, because of the peculiarities of cardiac muscle, the heart is somewhat more efficient in producing a given CO with higher SV and lower HR than the other way around. So, metabolic requirements depend on how a given CO is accomplished .

Question 50

Which of the following will decrease the mean circulatory filling pressure?
a. increased circulating blood volume
b. decreased arteriolar tone
c. increased venous tone

Answer 50

None of the choices are correct. (The tiny change in vascular volume that accompanies a decrease in arteriolar tone is not sufficient to have a significant effect on mean circulatory filling pressure.)

Question 51

What determines central venous pressure?

Answer 51

Central venous pressure always settles at the value that makes cardiac output and venous return equal. Therefore, anything that shifts the cardiac function curve or the venous return curve affects central venous pressure

Question 52

According to the Starling law, cardiac output always decreases when central venous pressure decreases. True or false?

Answer 52

False. Starling’s law of the heart says that, if other influences on the heart are constant, cardiac output decreases when central venous pressure decreases (e.g., A → B in Figure 8–7). In the intact cardiovascular system, where many things may happen simultaneously, cardiac output and central venous pressure may change in opposite directions (

Question 53

In a steady state, venous return will be greater than cardiac output when
a. peripheral venous pressure is higher than normal
b. blood volume is higher than normal
c. cardiac sympathetic nerve activity is lower than normal

Answer 53

None. Venous return must always equal cardiac output in the steady-state situation.

Question 54

What approaches might a physician logically pursue in an attempt to lower a patient’s cardiac preload?

Answer 54

Because cardiac preload is central venous pressure, the physician will try to lower central venous pressure. This requires a left shift of the venous return curve. The two ways that can be done are decreasing circulating volume or decreasing venous tone. The former is often accomplished with diuretic drugs, and the latter can be achieved with certain vasodilator drugs that specifically influence venous tone (i.e., venodilators)

Question 55

In a severely dehydrated patient, you might expect to find a. a depressed cardiac function curve
b. an increased mean circulatory filling pressure
c. an increased central venous pressure
d. distended jugular veins
e. decreased cardiac output

Answer 55

e. Dehydration directly tends to lower blood volume, mean circulatory filling pressure, cardiac filling pressure, end-diastolic volume, and stroke volume. Heart rate will increase as a compensatory response to maintain cardiac output and arterial pressure.

Question 56

If you gave a blood transfusion to a patient who had recently experienced a severe hemorrhage, you would expect
a. to expand arterial volume
b. to expand venous volume
c. to decrease central venous pressure
d. to decrease the mean circulatory filling pressure
e. to reduce cardiac output

Answer 56

b

Question 57

Which of the following would directly (by themselves in the absence of any compensatory responses) tend to decrease central venous (cardiac filling) pressure?
a. increased sympathetic nerve activity to only the heart
b. increased parasympathetic nerve activity to only the heart
c. increased blood volume
d. decreased total peripheral resistance
e. immersion in water up to the waist

Answer 57

a

Question 58

How are the thin-walled capillaries in the feet able to withstand pressures greater than 100 mm Hg in a standing individual without rupturing?

Answer 58

Because capillaries have such a small radius, according to the law of Laplace ( T = P × r), the tension in the capillary wall is rather modest despite very high internal pressures.

Question 59

The “iron lung,” used to help polio victims breathe in the mid- 20th century, applied an external intermittent negative pressure to the patient’s thoracic cavity. How might this be better than positive-pressure artificial ventilation of the patient’s lungs?

Answer 59

The external negative pressure served to expand the thorax and “pull” air into the lungs through the patient’s airways in much the same way that the thoracic muscle and diaphragm expand the thorax in normal breathing. This method of ventilating the lungs did not have the adverse cardiovascular consequences that positive-pressure artificial ventilation has.

Question 59

Soldiers faint when standing at attention on a very hot day more often than on a cooler day. Why?

Answer 59

Fainting occurs because of decreased cerebral blood flow when mean arterial pressure falls below approximately 60 mm Hg. On a hot day, temperature reflexes override pressure reflexes to produce the increased skin blood flow required for thermal regulation. Thus, TPR may be lower when standing on a hot day than on a cool one. This vasodilation combined with the absence of the skeletal muscle pump during standing motionless at attention makes it quite likely that brain blood flow will be compromised.

Question 60

For several days after an extended period of bed rest, patients often become dizzy when they stand upright quickly because of an exaggerated transient fall in arterial pressure (orthostatic hypotension). Why might this be so?

Answer 60

The cardiovascular response to lying down is just the opposite of that shown in Figure 10–3. Therefore, during extended bed rest, patients tend to lose rather than retain fluid and end up with lower-than-normal blood volumes. Because of low blood volume, central venous pressure and cardiac filling are significantly reduced when the patient assumes an upright posture. Short-term compensatory actions (increased sympathetic drive, skeletal muscle pump, and respiratory pump) may be inadequate and blood pressure may fall. This may lead to a decrease in brain blood flow and dizziness ensues. Such patients are less able to cope with standing until blood volume is restored to normal values.

Question 61

Phenylephrine is a drug that specifically stimulates cardiovascular α -adrenergic receptors. If you gave phenylephrine to a patient, what would you expect would happen to sympathetic nerve activity, to myocardial contractility, to total peripheral resistance, and to heart rate?

Question 62

Your 70-year-old 70-kg patient has an ejection fraction of 67% at rest. Left ventricular end-diastolic volume is 210 mL. Which of the following statements best fits these data?
a. These are normal data for someone this age.
b. Your patient may be a competitive polka dancer.
c. Your patient may be suffering from chronic systolic heart
failure.
d. Your patient may be severely hypovolemic.
e. Stroke volume is ∼70 mL.

Answer 62

b. Stroke volume is ∼140 mL which is higher-than-normal at rest. High stroke volumes (coupled with low resting heart rates) are typical for trained athletes.

Question 63

Which of the following represents a normal compensatory response to chronic endurance exercise training?
a. an increase in circulating blood volume
b. an increase in the resting heart rate
c. an increase in resting mean arterial pressure
d. a decrease in resting stroke volume
e. a decrease in resting blood flow to the kidneys

Answer 63

a

Question 64

All of the following tend to occur when a person lies down.
Which one is the primary disturbance that causes all the others to happen?
a. The heart rate will decrease.
b. Cardiac contractility will increase.
c. Sympathetic activity will decrease.
d. Parasympathetic activity will increase.
e. Central venous pressure will increase.

Answer 64

e. All other choices are part of the reflex compensatory responses to the increase in central venous pressure.

Question 65

Aortic stiffness may increase substantially with old age. What is/are the expected consequences of this change?
a. an increase in total peripheral resistance
b. an increase in stroke volume
c. an increase in pulse pressure
d. an increase in mean arterial pressure

Answer 65

C

Question 66

Clinical signs of hypovolemic shock often include pale and cold skin, dry mucous membranes, weak but rapid pulse, muscle weakness, and mental disorientation or unconsciousness. What are the physiological conditions that account for these signs?

Answer 66

Intense sympathetic activation drastically reduces skin blood flow, promotes transcapillary reabsorption of fluids, increases the heart rate and contractility (but may not restore stroke volume because of low central venous pressure), and reduces skeletal muscle blood flow. Cerebral blood flow falls if the compensatory mechanisms do not prevent mean arterial pressure from falling below 60 mm Hg.

Question 67

Which of the following would be helpful to hemorrhagic shock victims?
a. Keep them on their feet.
b. Warm them up.
c. Give them fluids to drink.
d. Maintain their blood pressure with catecholamine-type drugs.

Answer 67

a. Not helpful because gravity tends to promote peripheral venous blood pooling and cause a further fall in arterial pressure.
b. Not helpful if carried to an extreme. Cutaneous vasodilation produced by warming adds to the cardiovascular stresses.
c. Helpful if the victim is conscious and can drink because fluid will be rapidly absorbed from the gut to increase circulating blood volume.
d. Might be helpful as an initial emergency measure to prevent brain damage due to severely reduced blood pressure, but prolonged treatment will promote the decompensatory mechanisms associated with decreased organ blood flow.