Cardiac Cycle - Homework Questions

When the heart rate is 70 beats per minute and the stroke volume is 80 mL, what is cardiac output?

5600 mL/min

Increased pressure in the ventricles would close what valve(s)?

AV valves only

Which of the following is correct about the filling of the ventricles

Most blood flows passively into the ventricles through open AV valves

Describe the pressures in the atria and ventricles that would cause the opening of the AV valves

Pressure in the atria would be greater than the pressure in the ventricles.

Ventricular systole is triggered by the

Purkinje fibers

What affect does sympathetic stimulation of the heart have on heart rate and stroke volume?

Sympathetic stimulation of the heart increases both heart rate and stroke volume.

Put these events of the cardiac cycle in the correct order, starting after ventricular filling.

Ventricles contract, AV valves close, semilunar valves open, ventricles relax, and semilunar valves close.

Contraction of the upper chambers of the heart is called

atrial systol

Sympathetic innervation travels to the heart via the

cardiac nerve

The indicator of peripheral blood flow is

cardiac output

How would a moderate decrease in blood volume affect both stroke volume and cardiac output?

decreased stroke volume and no change in cardiac output

Which of the following would increase heart rate?

epinephrine and norepinephrine

Which of the following would increase stroke volume?

exercise

What causes the aortic semilunar valve to close?

greater pressure in the aorta than in the left ventricle

Which of the following would increase cardiac output to the greatest extent?

increased heart rate and increased stroke volume

During light exercise, the increase in cardiac output is mostly due to

increased venous return.

The first phase of ventricular systole which builds pressure but does not create enough pressure to open the semilunar valves is

isovolumetric contraction

Which of the following will NOT increase heart rate?

parasympathetic stimulation

Which of the following will NOT decrease venous return?

skeletal muscle contraction

During heavy exercise cardiac output increases approximately ________ and skeletal muscle blood flow increases ________.

three-fold; ten-fold

Parasympathetic innervation travels to the heart via the

vagus nerve

The amount of blood arriving at the right ventricle each minute is

venous return

Ventricular filling takes place during

ventricular diastole

Relaxation of the lower chambers of the heart is called

ventricular diastole.

The phase of ventricular systole that creates enough pressure to open the semilunar valves is

ventricular ejection.