Deck 3: Cardiovascular Physiology

Question 1

A 53-year-old woman is found, by arteriography, to have $50 \%$ narrowing of her left renal artery. What is the expected change in blood flow through the stenotic artery?

A) Decrease to $1 / 2$
B) Decrease to $1 / 4$
C) Decrease to $1 / 8$
D) Decrease to $1 / 16$
E) No change

Answer 1

Decrease to $1 / 16$

Question 2

When a person moves from a supine position to a standing position, which of the following compensatory changes occurs?

A) Decreased heart rate
B) Increased contractility
C) Decreased total peripheral resistance (TPR)
D) Decreased cardiac output
E) Increased PR intervals

Answer 2

Increased contractility

Question 3

At which site is systolic blood pressure the highest?

A) Aorta
B) Central vein
C) Pulmonary artery
D) Right atrium
E) Renal artery
F) Renal vein

Answer 3

Renal artery

Question 4

A person's electrocardiogram (ECG) has no $\mathrm{P}$ wave, but has a normal QRS complex and a normal $\mathrm{T}$ wave. Therefore, his pacemaker is located in the

A) sinoatrial (SA) node
B) atrioventricular (AV) node
C) bundle of His
D) Purkinje system
E) ventricular muscle

Question 5

If the ejection fraction increases, there will be a decrease in

A) cardiac output
B) end-systolic volume
C) heart rate
D) pulse pressure
E) stroke volume
F) systolic pressure

Question 6

An electrocardiogram (ECG) on a person shows ventricular extrasystoles.

-The extrasystolic beat would produce

A) increased pulse pressure because contractility is increased
B) increased pulse pressure because heart rate is increased
C) decreased pulse pressure because ventricular filling time is increased
D) decreased pulse pressure because stroke volume is decreased
E) decreased pulse pressure because the PR interval is increased

Question 7

An electrocardiogram (ECG) on a person shows ventricular extrasystoles.

-After an extrasystole, the next "normal" ventricular contraction produces

A) increased pulse pressure because the contractility of the ventricle is increased
B) increased pulse pressure because total peripheral resistance (TPR) is decreased
C) increased pulse pressure because compliance of the veins is decreased
D) decreased pulse pressure because the contractility of the ventricle is increased
E) decreased pulse pressure because TPR is decreased

Question 8

An increase in contractility is demonstrated on a Frank-Starling diagram by

A) increased cardiac output for a given enddiastolic volume
B) increased cardiac output for a given endsystolic volume
C) decreased cardiac output for a given end-diastolic volume
D) decreased cardiac output for a given end-systolic volume

Question 9

-On the graph showing left ventricular volume and pressure, isovolumetric contraction occurs between points

A) $4 \rightarrow 1$
B) $1 \rightarrow 2$
C) $2 \rightarrow 3$
D) $3 \rightarrow 4$

Question 10

-The aortic valve closes at point

A) 1
B) 2
C) 3
D) 4

Question 11

-The first heart sound corresponds to point

A) 1
B) 2
C) 3
D) 4

Question 12

-If the heart rate is 70 beats/min, then the cardiac output of this ventricle is closest to

A) $3.45 \mathrm{~L} / \mathrm{min}$
B) $4.55 \mathrm{~L} / \mathrm{min}$
C) $5.25 \mathrm{~L} / \mathrm{min}$
D) $8.00 \mathrm{~L} / \mathrm{min}$
E) $9.85 \mathrm{~L} / \mathrm{min}$

Question 13

In a capillary, $\mathrm{P}_{\mathrm{c}}$ is $30 \mathrm{~mm} \mathrm{Hg}, \mathrm{P}_{\mathrm{i}}$ is $-2 \mathrm{~mm} \mathrm{Hg}$ , $\pi_{\mathrm{c}}$ is $25 \mathrm{~mm} \mathrm{Hg}$ , and $\pi_{\mathrm{i}}$ is $2 \mathrm{~mm} \mathrm{Hg}$ .

-What is the direction of fluid movement and the net driving force?

A) Absorption; $6 \mathrm{~mm} \mathrm{Hg}$
B) Absorption; $9 \mathrm{~mm} \mathrm{Hg}$
C) Filtration; $6 \mathrm{~mm} \mathrm{Hg}$
D) Filtration; $9 \mathrm{~mm} \mathrm{Hg}$
E) There is no net fluid movement

Question 14

In a capillary, $\mathrm{P}_{\mathrm{c}}$ is $30 \mathrm{~mm} \mathrm{Hg}, \mathrm{P}_{\mathrm{i}}$ is $-2 \mathrm{~mm} \mathrm{Hg}$ , $\pi_{\mathrm{c}}$ is $25 \mathrm{~mm} \mathrm{Hg}$ , and $\pi_{\mathrm{i}}$ is $2 \mathrm{~mm} \mathrm{Hg}$ .

-If $\mathrm{K}_{\mathrm{f}}$ is $0.5 \mathrm{~mL} / \mathrm{min} / \mathrm{mm} \mathrm{Hg}$ , what is the rate of water flow across the capillary wall?

A) $0.06 \mathrm{~mL} / \mathrm{min}$
B) $0.45 \mathrm{~mL} / \mathrm{min}$
C) $4.50 \mathrm{~mL} / \mathrm{min}$
D) $9.00 \mathrm{~mL} / \mathrm{min}$
E) $18.00 \mathrm{~mL} / \mathrm{min}$

Question 15

The tendency for blood flow to be turbulent is increased by

A) increased viscosity
B) increased hematocrit
C) partial occlusion of a blood vessel
D) decreased velocity of blood flow

Question 16

A 66-year-old man, who has had a sympathectomy, experiences a greaterthan-normal fall in arterial pressure upon standing up. The explanation for this occurrence is

A) an exaggerated response of the reninangiotensin-aldosterone system
B) a suppressed response of the reninangiotensin-aldosterone system
C) an exaggerated response of the baroreceptor mechanism
D) a suppressed response of the baroreceptor mechanism

Question 17

The ventricles are completely depolarized during which isoelectric portion of the electrocardiogram (ECG)?

A) PR interval
B) QRS complex
C) QT interval
D) ST segment
E) $\mathrm{T}$ wave

Question 18

In which of the following situations is pulmonary blood flow greater than aortic blood flow?

A) Normal adult
B) Fetus
C) Left-to-right ventricular shunt
D) Right-to-left ventricular shunt
E) Right ventricular failure
F) Administration of a positive inotropic agent

Question 19

The change indicated by the dashed lines on the cardiac output/venous return curves shows
Right atrial pressure $(\mathrm{mm} \mathrm{Hg})$ or end-diastolic volume (L)

A) decreased cardiac output in the "new" steady state
B) decreased venous return in the "new" steady state
C) increased mean systemic pressure
D) decreased blood volume
E) increased myocardial contractility

Question 20

A 30-year-old female patient's electrocardiogram (ECG) shows two $P$ waves preceding each QRS complex. The interpretation of this pattern is

A) decreased firing rate of the pacemaker in the sinoatrial (SA) node
B) decreased firing rate of the pacemaker in the atrioventricular (AV) node
C) increased firing rate of the pacemaker in the SA node
D) decreased conduction through the AV node
E) increased conduction through the HisPurkinje system

Question 21

An acute decrease in arterial blood pressure elicits which of the following compensatory changes?

A) Decreased firing rate of the carotid sinus nerve
B) Increased parasympathetic outflow to the heart
C) Decreased heart rate
D) Decreased contractility
E) Decreased mean systemic pressure

Question 22

The tendency for edema to occur will be increased by

A) arteriolar constriction
B) increased venous pressure
C) increased plasma protein concentration
D) muscular activity

Question 23

Inspiration "splits" the second heart sound because

A) the aortic valve closes before the pulmonic valve
B) the pulmonic valve closes before the aortic valve
C) the mitral valve closes before the tricuspid valve
D) the tricuspid valve closes before the mitral valve
E) filling of the ventricles has fast and slow components

Question 24

During exercise, total peripheral resistance (TPR) decreases because of the effect of

A) the sympathetic nervous system on splanchnic arterioles
B) the parasympathetic nervous system on skeletal muscle arterioles
C) local metabolites on skeletal muscle arterioles
D) local metabolites on cerebral arterioles
E) histamine on skeletal muscle arterioles

Question 25

-Curve A in the figure represents

A) aortic pressure
B) ventricular pressure
C) atrial pressure
D) ventricular volume

Question 26

-Curve $B$ in the figure represents

A) left atrial pressure
B) ventricular pressure
C) atrial pressure
D) ventricular volume

Question 27

An increase in arteriolar resistance, without a change in any other component of the cardiovascular system, will produce

A) a decrease in total peripheral resistance (TPR)
B) an increase in capillary filtration
C) an increase in arterial pressure
D) a decrease in afterload

Question 28

The following measurements were obtained in a male patient:
Central venous pressure: $10 \mathrm{~mm} \mathrm{Hg}$
Heart rate: 70 beats/min
Systemic arterial $\left[\mathrm{O}_{2}\right]=0.24 \mathrm{~mL} \mathrm{O}_{2} / \mathrm{mL}$
Mixed venous $\left[\mathrm{O}_{2}\right]=0.16 \mathrm{~mL} \mathrm{O}_{2} / \mathrm{mL}$
Whole body $\mathrm{O}_{2}$ consumption: $500 \mathrm{~mL} / \mathrm{min}$
What is this patient's cardiac output?

A) $1.65 \mathrm{~L} / \mathrm{min}$
B) $4.55 \mathrm{~L} / \mathrm{min}$
C) $5.00 \mathrm{~L} / \mathrm{min}$
D) $6.25 \mathrm{~L} / \mathrm{min}$
E) $8.00 \mathrm{~L} / \mathrm{min}$

Question 29

Which of the following is the result of an inward $\mathrm{Na}^{+}$ current?

A) Upstroke of the action potential in the sinoatrial (SA) node
B) Upstroke of the action potential in Purkinje fibers
C) Plateau of the action potential in ventricular muscle
D) Repolarization of the action potential in ventricular muscle
E) Repolarization of the action potential in the SA node

Question 30

Right atrial pressure $(\mathrm{mm} \mathrm{Hg})$

-The dashed line in the figure illustrates the effect of

A) increased total peripheral resistance (TPR)
B) increased blood volume
C) increased contractility
D) a negative inotropic agent
E) increased mean systemic pressure

Question 31

Right atrial pressure $(\mathrm{mm} \mathrm{Hg})$

-The $\mathrm{x}$ -axis in the figure could have been labeled

A) end-systolic volume
B) end-diastolic volume
C) pulse pressure
D) mean systemic pressure
E) heart rate

Question 32

The greatest pressure decrease in the circulation occurs across the arterioles because

A) they have the greatest surface area
B) they have the greatest cross-sectional area
C) the velocity of blood flow through them is the highest
D) the velocity of blood flow through them is the lowest
E) they have the greatest resistance

Question 33

Pulse pressure is

A) the highest pressure measured in the arteries
B) the lowest pressure measured in the arteries
C) measured only during diastole
D) determined by stroke volume
E) decreased when the capacitance of the arteries decreases
F) the difference between mean arterial pressure and central venous pressure

Question 34

In the sinoatrial (SA) node, phase 4 depolarization (pacemaker potential) is attributable to

A) an increase in $\mathrm{K}^{+}$ conductance
B) an increase in $\mathrm{Na}^{+}$ conductance
C) a decrease in $\mathrm{Cl}^{-}$ conductance
D) a decrease in $\mathrm{Ca}^{2+}$ conductance
E) simultaneous increases in $\mathrm{K}^{+}$ and $\mathrm{Cl}^{-}$ conductances

Question 35

A healthy 35 -year-old man is running a marathon. During the run, there is a increase in his splanchnic vascular resistance. Which receptor is responsible for the increased resistance?

A) $\alpha_{1}$ Receptors
B) $\beta_{1}$ Receptors
C) $\beta_{2}$ Receptors
D) Muscarinic receptors

Question 36

During which phase of the cardiac cycle is aortic pressure highest?

A) Atrial systole
B) Isovolumetric ventricular contraction
C) Rapid ventricular ejection
D) Reduced ventricular ejection
E) Isovolumetric ventricular relaxation
F) Rapid ventricular filling
G) Reduced ventricular filling (diastasis)

Question 37

Myocardial contractility is best correlated with the intracellular concentration of

A) $\mathrm{Na}^{+}$
B) $\mathrm{K}^{+}$
C) $\mathrm{Ca}^{2+}$
D) $\mathrm{Cl}^{-}$
E) $\mathrm{Mg}^{2+}$

Question 38

Which of the following is an effect of histamine?

A) Decreased capillary filtration
B) Vasodilation of the arterioles
C) Vasodilation of the veins
D) Decreased $\mathrm{P}_{\mathrm{c}}$
E) Interaction with the muscarinic receptors on the blood vessels

Question 39

Carbon dioxide $\left(\mathrm{CO}_{2}\right)$ regulates blood flow to which one of the following organs?

A) Heart
B) Skin
C) Brain
D) Skeletal muscle at rest
E) Skeletal muscle during exercise

Question 40

Cardiac output of the right side of the heart is what percentage of the cardiac output of the left side of the heart?

A) $25 \%$
B) $50 \%$
C) $75 \%$
D) $100 \%$
E) $125 \%$

Question 41

The physiologic function of the relatively slow conduction through the atrioventricular (AV) node is to allow sufficient time for

A) runoff of blood from the aorta to the arteries
B) venous return to the atria
C) filling of the ventricles
D) contraction of the ventricles
E) repolarization of the ventricles

Question 42

Blood flow to which organ is controlled primarily by the sympathetic nervous system rather than by local metabolites?

A) Skin
B) Heart
C) Brain
D) Skeletal muscle during exercise

Question 43

Which of the following parameters is decreased during moderate exercise?

A) Arteriovenous $\mathrm{O}_{2}$ difference
B) Heart rate
C) Cardiac output
D) Pulse pressure
E) Total peripheral resistance (TPR)

Question 44

A 72-year-old woman, who is being treated with propranolol, finds that she cannot maintain her previous exercise routine. Her physician explains that the drug has reduced her cardiac output. Blockade of which receptor is responsible for the decrease in cardiac output?

A) $\alpha_{1}$ Receptors
B) $\beta_{1}$ Receptors
C) $\beta_{2}$ Receptors
D) Muscarinic receptors
E) Nicotinic receptors

Question 45

During which phase of the cardiac cycle is ventricular volume lowest?

A) Atrial systole
B) Isovolumetric ventricular contraction
C) Rapid ventricular ejection
D) Reduced ventricular ejection
E) Isovolumetric ventricular relaxation
F) Rapid ventricular filling
G) Reduced ventricular filling (diastasis)

Question 46

Which of the following changes will cause an increase in myocardial $\mathrm{O}_{2}$ consumption?

A) Decreased aortic pressure
B) Decreased heart rate
C) Decreased contractility
D) Increased size of the heart
E) Increased influx of $\mathrm{Na}^{+}$ during the upstroke of the action potential

Question 47

Which of the following substances crosses capillary walls primarily through water-filled clefts between the endothelial cells?

A) $\mathrm{O}_{2}$
B) $\mathrm{CO}_{2}$
C) $\mathrm{CO}$
D) Glucose

Question 48

A 24-year-old woman presents to the emergency department with severe diarrhea. When she is supine (lying down), her blood pressure is $90 / 60 \mathrm{~mm} \mathrm{Hg}$ (decreased) and her heart rate is 100 beats/min (increased). When she is moved to a standing position, her heart rate further increases to 120 beats/ min. Which of the following accounts for the further increase in heart rate upon standing?

A) Decreased total peripheral resistance
B) Increased venoconstriction
C) Increased contractility
D) Increased afterload
E) Decreased venous return

Question 49

A 60-year-old businessman is evaluated by his physician, who determines that his blood pressure is significantly elevated at 185/130 mm Hg. Laboratory tests reveal an increase in plasma renin activity, plasma aldosterone level, and left renal vein renin level. His right renal vein renin level is decreased. What is the most likely cause of the patient's hypertension?

A) Aldosterone-secreting tumor
B) Adrenal adenoma secreting aldosterone and cortisol
C) Pheochromocytoma
D) Left renal artery stenosis
E) Right renal artery stenosis

Question 50

-During which phase of the ventricular action potential is the membrane potential closest to the $\mathrm{K}^{+}$ equilibrium potential?

A) Phase 0
B) Phase 1
C) Phase 2
D) Phase 3
E) Phase 4

Question 51

-During which phase of the ventricular action potential is the conductance to $\mathrm{Ca}^{2+}$ highest?

A) Phase 0
B) Phase 1
C) Phase 2
D) Phase 3
E) Phase 4

Question 52

-Which phase of the ventricular action potential coincides with diastole?

A) Phase 0
B) Phase 1
C) Phase 2
D) Phase 3
E) Phase 4

Question 53

Propranolol has which of the following effects?

A) Decreases heart rate
B) Increases left ventricular ejection fraction
C) Increases stroke volume
D) Decreases splanchnic vascular resistance
E) Decreases cutaneous vascular resistance

Question 54

Which receptor mediates slowing of the heart?

A) $\alpha_{1}$ Receptors
B) $\beta_{1}$ Receptors
C) $\beta_{2}$ Receptors
D) Muscarinic receptors

Question 55

Which of the following agents or changes has a negative inotropic effect on the heart?

A) Increased heart rate
B) Sympathetic stimulation
C) Norepinephrine
D) Acetylcholine (ACh)
E) Cardiac glycosides

Question 56

The low-resistance pathways between myocardial cells that allow for the spread of action potentials are the

A) gap junctions
B) T tubules
C) sarcoplasmic reticulum (SR)
D) intercalated disks
E) mitochondria

Question 57

Which agent is released or secreted after a hemorrhage and causes an increase in renal $\mathrm{Na}^{+}$ reabsorption?

A) Aldosterone
B) Angiotensin I
C) Angiotensinogen
D) Antidiuretic hormone (ADH)
E) Atrial natriuretic peptide

Question 58

During which phase of the cardiac cycle does the mitral valve open?

A) Atrial systole
B) Isovolumetric ventricular contraction
C) Rapid ventricular ejection
D) Reduced ventricular ejection
E) Isovolumetric ventricular relaxation
F) Rapid ventricular filling
G) Reduced ventricular filling (diastasis)

Question 59

A hospitalized patient has an ejection fraction of 0.4 , a heart rate of 95 beats/min, and a cardiac output of $3.5 \mathrm{~L} / \mathrm{min}$ . What is the patient's end-diastolic volume?

A) $14 \mathrm{~mL}$
B) $37 \mathrm{~mL}$
C) $55 \mathrm{~mL}$
D) $92 \mathrm{~mL}$
E) $140 \mathrm{~mL}$