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.
