Excess K+ ions in cardiac tissue cause heart rate and stroke volume to __________ and decreased extracellular K+ ions result in a __________ in heart rate.

Excess K+ ions in cardiac tissue cause heart rate and stroke volume to __________ and decreased extracellular K+ ions result in a __________ in heart rate.

a. decrease, decrease
b. decrease, increase
c. increase, decrease
d. increase, increase
e. be unchanged, increase

Answer: A

Generally, an increase in extracellular Ca2+ ions causes __________ force of contraction, and __________ heart rate.

Generally, an increase in extracellular Ca2+ ions causes __________ force of contraction, and __________ heart rate.

a. decreased, decreased
b. decreased, increased
c. increased, decreased
d. increased, increased

Answer: C

Increased sympathetic stimulation of the heart

Increased sympathetic stimulation of the heart

a. increases the force of ventricular contraction.
b. opens a larger number of calcium slow channels.
c. increases the heart rate.
d. increases cardiac output.
e. all of these

Answer: E

If blood pH decreases and blood carbon dioxide increases,

If blood pH decreases and blood carbon dioxide increases,

a. heart rate increases.
b. stroke volume decreases.
c. increased parasympathetic stimulation of the heart occurs.
d. the change is detected by chemoreceptors in the pulmonary arteries.
e. all of these

Answer: A

When normal arterial blood pressure decreases, baroreceptors cause a response that

When normal arterial blood pressure decreases, baroreceptors cause a response that

a. decreases heart rate.
b. decreases stroke volume.
c. returns blood pressure to normal.
d. results in parasympathetic stimulation of the heart.
e. all of these

Answer: C

Parasympathetic nerve fibers

Parasympathetic nerve fibers

a. are carried to the heart through the Accessory nerve (XI).
b. extend to terminal ganglia within the wall of the heart.
c. release the neurotransmitter norepinephrine.
d. if stimulated, result in an increased heart rate.
e. if stimulated, greatly increase stroke volume.

Answer: B

Increased venous return to the heart causes increased

Increased venous return to the heart causes increased

a. stroke volume.
b. preload.
c. cardiac output.
d. force of contraction.
e. all of these

Answer: E

Preload

Preload

a. is the extent to which the ventricular walls are stretched.
b. if increased, causes a decrease in cardiac output.
c. is the pressure in the aorta which contracting ventricles must overcome.
d. is part of the extrinsic regulation of the heart.
e. all of these

Answer: A

If the heart rate for a patient is 80 bpm, and her stroke volume is 70 mL/beat, then her cardiac output is

If the heart rate for a patient is 80 bpm, and her stroke volume is 70 mL/beat, then her cardiac output is

a. O.87 mL/min
b. 1.1 mL/min.
c. 10 mL/min.
d. 56 mL/min.
e. 5600 mL/min

Answer: E

The second heart sound, described as "dupp" is actually the sound of the

The second heart sound, described as "dupp" is actually the sound of the

a. atria contracting.
b. ventricles contracting.
c. atrioventricular valves closing.
d. semilunar valves closing.
e. heart slapping the liver.

Answer: D

During the period of ejection, the left ventricular pressure reaches a high point of approximately

During the period of ejection, the left ventricular pressure reaches a high point of approximately

a. 20 mm Hg.
b. 60 mm Hg.
c. 80 mm Hg.
d. 100 mm Hg.
e. 120 mm Hg.

Answer: E

The average end-diastolic volume of the ventricles is about __________ , whereas the end-systolic volume is about __________ .

The average end-diastolic volume of the ventricles is about __________ , whereas the end-systolic volume is about __________ .

a. 125 mL, 55 mL
b. 125 mL, 0 mL
c. 0 mL, 55 mL
d. 0 mL, 125 mL
e. 55 mL, 125 mL

Answer: A

At the end of __________ , the ventricles are 70% filled.

At the end of __________ , the ventricles are 70% filled.

a. active ventricular filling
b. passive ventricular filling
c. ventricular diastole
d. ventricular systole
e. atrial systole

Answer: B

Blood flows neither into nor out of the ventricles during

Blood flows neither into nor out of the ventricles during

a. the period of isovolumic contraction.
b. the period of isovolumic relaxation.
c. systole.
d. diastole.
e. both a and b

Answer: E

During the period of ejection in the cardiac cycle, the atrioventricular valves are __________ and the semilunar valves are __________ .

During the period of ejection in the cardiac cycle, the atrioventricular valves are __________ and the semilunar valves are __________ .

a. closed, closed
b. closed, open
c. open, closed
d. open, open

Answer: B

Which of these conditions is most likely to cause bradycardia?

Which of these conditions is most likely to cause bradycardia?

a. ectopic action potentials in the atria
b. damage to the tricuspid valve
c. excessive sympathetic stimulation
d. excessive parasympathetic stimulation
e. too much coffee

Answer: D

During the QT interval of the EKG, the

During the QT interval of the EKG, the

a. atria contract and begin to relax.
b. atria relax.
c. ventricles contract and begin to relax.
d. ventricles relax.

Answer: C

In an EKG, the P wave represents

In an EKG, the P wave represents

a. depolarization of the atria.
b. repolarization of the atria.
c. depolarization of the ventricles.
d. repolarization of the ventricles.

Answer: A

Which of these conditions results in a prepotential in pacemaker cells?

Which of these conditions results in a prepotential in pacemaker cells?

a. Na+ ions move into the cell through specialized Na+ ion channels.
b. Membrane permeability to K+ ions increases.
c. Voltage-gated Ca2+ ion channels close.
d. all of these are correct

Answer: A

Unlike other cardiac muscle cells, the movement of __________ into the pacemaker cells is primarily responsible for the depolarization phase of the action potential.

Unlike other cardiac muscle cells, the movement of __________ into the pacemaker cells is primarily responsible for the depolarization phase of the action potential.

a. Ca2+ ions
b. K+ ions
c. Na+ ions
d. Cl- ions

Answer: A