Cardiac output is best defined as the volume of blood pumped each minute into the:

A. pulmonary artery
B. aorta
C. left atrium
D. vena cava

B. aorta

Venous return is the volume of blood entering the heart each minute through the:

A. left ventricle
B. pulmonary veins
C. aorta
D. right atrium

D. right atrium

At rest, young healthy men generally have ______ cardiac output than women.

A. lower
B. equal
C. greater
D. more variable

C. greater

The average resting cardiac output of an adult is closest to:

A. 3 L/min
B. 4 L/min
C. 7 L/min
D. 5 L/min

D. 5 L/min

When indexed to body size, cardiac output generally ______ with greater body surface area.

A. decreases
B. increases
C. normalizes downward
D. becomes unpredictable

B. increases

Cardiac index is best defined as cardiac output per:

A. kilogram body weight
B. beat-to-beat interval
C. square meter body surface
D. milliliter stroke volume

C. square meter body surface

A declining cardiac index with aging most strongly suggests declining:

A. plasma osmolarity and muscle mass
B. vascular compliance and muscle mass
C. renal filtration and muscle mass
D. activity and muscle mass

D. activity and muscle mass

A sudden rise in venous return stretches ventricular muscle, causing a stronger contraction that ejects the extra blood. This is the:

A. Bainbridge reflex
B. Fick principle
C. Frank-Starling law
D. baroreceptor reflex

C. Frank-Starling law

Stretch of the right atrium also triggers which reflex increase in heart rate?

A. Cushing reflex
B. Bainbridge reflex
C. Bezold-Jarisch reflex
D. chemoreceptor reflex

B. Bainbridge reflex

The Bainbridge reflex first sends afferent information to the:

A. vasomotor center
B. SA node
C. carotid sinus
D. adrenal medulla

A. vasomotor center

Local tissue blood flow usually ______ when tissue oxygen consumption rises.

A. decreases
B. oscillates
C. increases
D. plateaus

C. increases

In a person with a normal heart, total cardiac output is determined mainly by the:

A. central venous pressure
B. left ventricular thickness
C. aortic compliance
D. tissues’ metabolic needs

D. tissues’ metabolic needs

When total peripheral resistance rises above normal, cardiac output usually:

A. increases
B. decreases
C. stays fixed
D. doubles

B. decreases

A heart pumping better than normal is termed:

A. hypoeffective
B. compensated
C. hypereffective
D. overfilled

C. hypereffective

A heart pumping below normal is termed:

A. overdistended
B. hypertrophied
C. hypereffective
D. hypoeffective

D. hypoeffective

Which pair can make the heart a better pump than normal?

A. nervous stimulation, hypertrophy
B. vagal excess, bradycardia
C. increased TPR, afterload
D. venous pooling, dilation

A. nervous stimulation, hypertrophy

Maximum pumping effectiveness rises most with sympathetic ______ plus parasympathetic ______.

A. inhibition, stimulation
B. withdrawal, stimulation
C. blockade, activation
D. stimulation, inhibition

D. stimulation, inhibition

With strong sympathetic stimulation plus parasympathetic inhibition, the plateau of the cardiac output curve can rise to about:

A. twice normal
B. half normal
C. 10% above normal
D. unchanged normal

A. twice normal

A patient with severe longstanding hypertension develops reduced cardiac pumping performance because the ventricle must eject against a markedly elevated afterload. This is best described as:

A. Hypoeffectivity
B. Hypereffectivity
C. Cardiac reserve
D. Autoregulation

A. Hypoeffectivity

Which factor can directly cause cardiac hypoeffectivity?

A. Reduced afterload
B. Nervous inhibition of the heart
C. Decreased venous capacitance
D. Lower systemic resistance

B. Nervous inhibition of the heart

During exercise, increased metabolism in active skeletal muscle acts directly on local arterioles to:

A. Constrict them
B. Relax them
C. Occlude them
D. Fibrose them

B. Relax them

Despite local arteriolar relaxation in active muscle, the nervous system still tends to:

A. Lower venous return
B. Decrease arterial pressure
C. Increase total arterial pressure
D. Abolish sympathetic tone

C. Increase total arterial pressure

High-output states are classically associated with:

A. Increased total peripheral resistance
B. Reduced total peripheral resistance
C. Markedly increased afterload
D. Decreased venous capacitance

B. Reduced total peripheral resistance

In beriberi, the primary peripheral vascular abnormality is:

A. Vasospasm
B. Peripheral vasodilation
C. Arteriolar thrombosis
D. Venous obstruction

B. Peripheral vasodilation

The fall in total peripheral resistance in beriberi tends to cause venous return and cardiac output to:

A. Drop to half normal
B. Stay near normal
C. Rise, often near double
D. Oscillate unpredictably

C. Rise, often near double

An arteriovenous fistula typically causes:

A. Higher TPR, lower CO
B. Lower TPR, higher CO
C. Higher TPR, lower VR
D. Lower TPR, lower VR

B. Lower TPR, higher CO

Hyperthyroidism raises cardiac output mainly because tissue metabolism and oxygen use increase, causing release of:

A. Vasodilator products
B. Vasoconstrictor peptides
C. Fibrinolytic enzymes
D. Oncotic proteins

A. Vasodilator products

In anemia, cardiac output rises partly because blood viscosity is:

A. Increased
B. Reduced
C. Unchanged
D. Highly variable

B. Reduced

In anemia, decreased oxygen delivery to tissues tends to:

A. Increase TPR
B. Decrease cardiac output
C. Decrease TPR, raise CO
D. Increase pleural pressure

C. Decrease TPR, raise CO

Abnormally low cardiac output is caused mainly by abnormalities that reduce pumping effectiveness and:

A. Increase venous return
B. Decrease venous return
C. Increase tissue oxygen use
D. Decrease afterload

B. Decrease venous return

When cardiac output falls so low that tissues develop widespread nutritional deficiency, the condition is called:

A. Distributive shock
B. Neurogenic syncope
C. Cardiogenic edema
D. Cardiac shock

D. Cardiac shock

Decrease in cardiac output from noncardiac peripheral causes is due mainly to:

A. Reduced venous return
B. Reduced coronary flow
C. Increased contractility
D. Increased pulse pressure

A. Reduced venous return

Acute venous dilation with fainting most often follows sudden inactivity of the:

A. Parasympathetic system
B. Enteric nervous system
C. Sympathetic nervous system
D. Somatic motor system

C. Sympathetic nervous system

Loss of skeletal muscle mass tends to lower cardiac output because it decreases total tissue:

A. Sodium retention
B. Oxygen consumption
C. Venous pressure
D. Hemoglobin content

B. Oxygen consumption

Hypothyroidism lowers cardiac output chiefly because it reduces:

A. Metabolic rate
B. Blood viscosity
C. Intrapleural pressure
D. Venous compliance

A. Metabolic rate

The normal external pressure outside the heart is approximately equal to normal intrapleural pressure, which is about:

A. 0 mm Hg
B. +4 mm Hg
C. −4 mm Hg
D. −10 mm Hg

C. −4 mm Hg

During normal breathing, cyclical respiratory changes in intrapleural pressure are about:

A. ±2 mm Hg
B. ±5 mm Hg
C. ±20 mm Hg
D. ±50 mm Hg

A. ±2 mm Hg

During strenuous breathing, intrapleural pressure swings may become as large as:

A. ±10 mm Hg
B. ±25 mm Hg
C. ±35 mm Hg
D. ±50 mm Hg

D. ±50 mm Hg

A patient generates strongly negative intrathoracic pressure during inspiration against resistance. The cardiac output curve shifts:

A. Upward
B. Leftward
C. Downward
D. Rightward

C. Downward

Accumulation of fluid in the pericardial sac that raises external cardiac pressure is called:

A. Pleural effusion
B. Cardiac tamponade
C. Tension pneumothorax
D. Constrictive bronchiolitis

B. Cardiac tamponade

Cardiac tamponade shifts the cardiac output curve:

A. Left
B. Down
C. Right
D. Up

B. Down

Cardiac tamponade = fluid compressing the heart → limits ventricular filling → ↓ stroke volume → ↓ cardiac output.

The main hemodynamic reason tamponade shifts the cardiac output curve is:

A. Lower venous tone
B. Reduced afterload
C. Increased external pressure
D. Greater sympathetic drive

C. Increased external pressure

A hypereffective heart combined with increased intrapleural pressure would be expected to produce:

A. Lower maximum output
B. Increased maximum output
C. Fixed venous return
D. Zero atrial pressure

B. Increased maximum output

Which pressure exerts a backward force that impedes venous return into the heart?

A. Mean arterial pressure
B. Right atrial pressure
C. Pulmonary wedge pressure
D. Pulse pressure

B. Right atrial pressure

Which pressure is the main forward force driving systemic blood toward the heart?

A. Right ventricular pressure
B. Mean systemic filling pressure
C. Capillary hydrostatic pressure
D. Intrapleural pressure

B. Mean systemic filling pressure

When cardiac pumping ability falls, right atrial pressure usually:

A. Decreases
B. Is unchanged
C. Increases
D. Becomes negative

C. Increases

As right atrial pressure rises from impaired pumping, venous return usually:

A. Increases
B. Decreases
C. Oscillates
D. Plateaus upward

B. Decreases

If all nervous circulatory reflexes are abolished, venous return falls to zero when right atrial pressure reaches about:

A. +2 mm Hg
B. +5 mm Hg
C. +7 mm Hg
D. +10 mm Hg

C. +7 mm Hg

The plateau of the normal venous return curve at negative atrial pressures is caused by:

A. Arteriolar spasm
B. Large vein collapse
C. Ventricular failure
D. Capillary filtration

B. Large vein collapse

Very negative right atrial pressure cannot keep increasing venous return because it eventually causes:

A. Venous thrombosis
B. Large-vein collapse
C. Arterial constriction
D. Atrial fibrillation

B. Large-vein collapse

When all systemic flow stops, arterial and venous pressures equilibrate near 7 mm Hg. This value is the:

A. Mean arterial pressure
B. Mean pulmonary pressure
C. Mean systemic filling pressure
D. Right ventricular pressure

C. Mean systemic filling pressure

When blood flow ceases everywhere and all vascular pressures equalize, that equilibrated pressure is called:

A. Mean circulatory filling pressure
B. Mean systolic filling pressure
C. Central venous pressure
D. Effective filling pressure

A. Mean circulatory filling pressure

The greater the blood volume in the circulation, the ______ the mean circulatory filling pressure.

A. lower
B. more variable
C. less relevant
D. greater

D. greater

Sympathetic stimulation changes vascular capacitance and filling pressure in which direction?

A. Higher capacitance, lower mean systemic filling pressure
B. Lower capacitance, higher mean systemic filling pressure
C. Lower capacitance, lower mean systemic filling pressure
D. Higher capacitance, higher mean systemic filling pressure

B. Lower capacitance, higher mean systemic filling pressure

Complete inhibition of the sympathetic nervous system tends to ______ mean circulatory filling pressure.

A. increase
B. stabilize
C. decrease
D. double

C. decrease

Mean systemic filling pressure is usually nearly equal to mean circulatory filling pressure because the pulmonary circulation has:

A. very high resistance
B. very low capacitance
C. much higher volume
D. major autoregulation only

B. very low capacitance

As mean systemic filling pressure rises, the venous return curve shifts:

A. Upward and rightward
B. Upward and leftward
C. Downward and rightward
D. Downward and leftward

A. Upward and rightward

As mean systemic filling pressure falls, the venous return curve shifts:

A. Upward and leftward
B. Downward and rightward
C. Downward and leftward
D. Rightward only

C. Downward and leftward

As right atrial pressure progressively falls below mean systemic filling pressure, venous return:

A. Decreases abruptly
B. Increases proportionately
C. Becomes fixed
D. Falls to zero

B. Increases proportionately

Venous return becomes zero when right atrial pressure is:

A. Lower than Psf
B. Equal to Psf
C. Higher than MAP
D. Equal to CVP only

B. Equal to Psf

Why is a rise in venous pressure relatively ineffective at overcoming resistance to venous return?

A. Veins are highly distensible
B. Veins actively constrict first
C. Arterioles collapse first
D. Atria become noncompliant

A. Veins are highly distensible

A rise in which pressure is most effective at overcoming resistance to venous return?

A. Capillary pressure
B. Venous pressure
C. Arteriolar pressure
D. Right atrial pressure

C. Arteriolar pressure

In normal steady-state circulation, venous return must equal:

A. Stroke volume
B. Heart rate
C. Cardiac output
D. Pulse pressure

C. Cardiac output

In a normal person, the equilibrium cardiac output is closest to:

A. 3 L/min
B. 5 L/min
C. 7 L/min
D. 9 L/min

B. 5 L/min

At the normal equilibrium point, right atrial pressure is about:

A. −4 mmHg
B. +7 mmHg
C. 0 mmHg
D. +2 mmHg

C. 0 mmHg

Increased blood volume raises cardiac output initially. Which compensatory change then increases fluid movement into tissues?

A. Lower capillary pressure
B. Higher capillary pressure
C. Lower venous tone
D. Higher oncotic pressure

B. Higher capillary pressure

After increased blood volume, stress-relaxation of veins tends to ______ mean systemic filling pressure.

A. increase
B. double
C. stabilize
D. reduce

D. reduce

Simple idea:

• When blood volume first increases → veins stretch → ↑ mean systemic filling pressure (MSFP)
• Then stress-relaxation happens: veins gradually relax and become more compliant

An increased cardiac output can trigger autoregulatory changes that ______ peripheral vascular resistance.

A. reduce
B. increase
C. abolish
D. normalize downward

B. increase

By increasing peripheral vascular resistance, this autoregulatory response tends to ______ cardiac output.

A. increase further
B. double immediately
C. decrease
D. fix it permanently

C. decrease

Sympathetic stimulation raises mean systemic filling pressure mainly by:

A. Arterial dilation and vascular constriction
B. Venous and vascular constriction
C. Lowering blood volume and vascular constriction
D. Increasing atrial compliance and vascular constriction

B. Venous and vascular constriction

Sympathetic stimulation also tends to ______ resistance to venous return.

A. decrease
B. normalize
C. increase
D. abolish

C. increase

Which intervention would most likely lower mean systemic filling pressure by blocking sympathetic transmission?

A. Epinephrine infusion
B. Total spinal anesthesia
C. Angiotensin infusion
D. Volume expansion alone

B. Total spinal anesthesia

Which drug classically lowers mean systemic filling pressure by blocking autonomic ganglia?

A. Propranolol
B. Atropine
C. Hexamethonium
D. Phenylephrine

C. Hexamethonium

Total spinal anesthesia or hexamethonium would be expected to:

A. Raise Psf and CO
B. Lower Psf and CO
C. Raise Psf only
D. Lower CO only

B. Lower Psf and CO

During major sympathetic stimulation or inhibition, which variable changes little at the new equilibrium?

A. Mean systemic pressure
B. Right atrial pressure
C. Venous resistance
D. Cardiac output curve

B. Right atrial pressure

Immediately after opening a large arteriovenous fistula, resistance to venous return:

A. markedly increases
B. slightly increases
C. markedly decreases
D. remains unchanged

C. markedly decreases

Immediately after opening a large AV fistula, the cardiac output curve shows a:

A. slight increase
B. major decrease
C. leftward shift only
D. fall in plateau

A. slight increase

Several weeks after creation of a large AV fistula, the kidneys tend to:

A. increase urine output
B. reduce urine output
C. waste potassium only
D. excrete pure water

B. reduce urine output

Large AV fistula → ↓ total peripheral resistance → ↓ effective arterial pressure sensed by kidneys → kidneys activate RAAS → retain Na⁺ and water → ↓ urine output

Over weeks with a persistent AV fistula, the heart muscle tends to:

A. atrophy markedly
B. fibrose rapidly
C. hypertrophy slightly
D. lose compliance only

C. hypertrophy slightly

Cardiac output is calculated as:

A. SV ÷ HR
B. HR ÷ SV
C. SV × HR
D. MAP × HR

C. SV × HR

On an aortic electromagnetic flow tracing, blood flow normally rises to a ______ during systole.

A. trough
B. plateau
C. nadir
D. peak

D. peak

Brief reverse flow at end-systole helps the aortic valve to:

A. open wider
B. close
C. prolapse
D. calcify

B. close

For the Fick method, the mixed venous sample is best taken from the:

A. right ventricle
B. pulmonary artery
C. femoral vein
D. superior vena cava

B. pulmonary artery

For the Fick method, the arterial sample can be taken from:

A. only the aorta
B. only the carotid
C. any systemic artery
D. only the brachial

C. any systemic artery

A normal cardiac index is approximately:

A. 1 L/min/m²
B. 2 L/min/m²
C. 3 L/min/m²
D. 5 L/min/m²

C. 3 L/min/m²

With increasing age, cardiac output generally:

A. increases
B. decreases
C. stays fixed
D. doubles first

B. decreases

Which statement best distinguishes cardiac output from venous return in normal physiology?

A. They are usually unequal
B. CO exceeds VR
C. VR exceeds CO
D. They are equal

D. They are equal

Which pair can produce a hypoeffective heart?

A. Beriberi and anemia
B. Hypertension and myocarditis
C. AV fistula and hyperthyroidism
D. Exercise and sympathetic drive

B. Hypertension and myocarditis

Dinitrophenol is best classified here as a:

A. positive inotrope
B. potent vasoconstrictor
C. potent vasodilator
D. ganglion blocker

C. potent vasodilator

The long-term hemodynamic effect of beriberi is:

A. increased TPR, lower CO
B. lower VR, lower CO
C. fixed TPR, fixed CO
D. increased VR and CO

D. increased VR and CO

In anemia, the usual pattern is:

A. increased TPR, increased CO
B. decreased TPR, increased CO
C. increased TPR, decreased CO
D. decreased TPR, decreased CO

B. decreased TPR, increased CO

A large arteriovenous fistula most directly causes:

A. increased TPR, lower CO
B. lower TPR, lower CO
C. lower TPR, higher CO
D. increased TPR, higher CO

C. lower TPR, higher CO

Cardiac tamponade most directly causes:

A. decreased cardiac output
B. increased venous return
C. increased cardiac output
D. no change in output

A. decreased cardiac output

Myocarditis generally causes:

A. increased CO
B. unchanged CO
C. increased VR
D. decreased CO

D. decreased CO

In hypothyroidism, venous return usually:

A. increases
B. is unchanged
C. decreases
D. becomes pressure-independent

C. decreases

Normal intrapleural pressure is closest to:

A. 0 to +2 mmHg
B. −4 to −2 mmHg
C. +2 to +4 mmHg
D. −8 to −6 mmHg

B. −4 to −2 mmHg

If right atrial pressure falls below 0 mmHg, venous return no longer rises because:

A. arterioles collapse
B. the SA node slows
C. Psf falls to zero
D. large veins collapse

D. large veins collapse

Sympathetic stimulation tends to ______ mean circulatory filling pressure.

A. increase
B. decrease
C. abolish
D. not affect

A. increase

Mean systemic filling pressure is best defined as the pressure in the systemic circulation after:

A. maximal exercise
B. inspiration
C. flow is stopped
D. venous return doubles

C. flow is stopped

At a constant filling pressure, strong sympathetic stimulation tends to ______ vascular capacitance.

A. increase
B. normalize
C. ignore
D. decrease

D. decrease

Venous return rises when the difference between Psf and right atrial pressure:

A. becomes greater
B. becomes zero
C. reverses direction
D. becomes irrelevant

A. becomes greater

About two thirds of resistance to venous return is determined by:

A. arteriolar resistance
B. capillary resistance
C. venous resistance
D. atrial resistance

C. venous resistance

Which formula best represents venous return?

A. Psf × RAP × RVR
B. (Psf − RAP) / RVR
C. RAP / Psf
D. (RAP − Psf) / RVR

B. (Psf − RAP) / RVR

If right atrial pressure increases, venous return usually:

A. increases
B. stays constant
C. first rises then falls
D. decreases

D. decreases

When right atrial pressure equals mean systemic filling pressure, venous return:

A. doubles
B. equals stroke volume
C. falls to zero
D. becomes pulsatile only

C. falls to zero

The Fick principle calculates cardiac output as:

A. oxygen uptake / AV O2 difference
B. stroke volume × heart rate
C. dye dilution × time
D. RAP / venous return

A. oxygen uptake / AV O2 difference

The indicator dilution method involves:

A. ultrasound through the esophagus
B. dye into vein or RA
C. oxygen uptake measurement
D. pulse contour analysis

B. dye into vein or RA

Echocardiography estimates cardiac output using:

A. ultrasound waves
B. radioactive tracer
C. arterial dye sampling
D. oxygen extraction curves

A. ultrasound waves