Wiley Plus Chapter 20 Cardiac Output

If the heart rate is 65 beats/min and the stroke volume is 70 ml, cardiac output is 135 ml/min.

False (so what is it?)

Stroke volume is regulated by:

Preload Contractility of the individual ventricular muscle fibers Afterload or the pressure that must be exceeded before ejection of blood from the ventricles can occur

Cardiac output equals the stroke volume multiplied by the heart rate.

True

Parasympathetic nervous system stimulation of the heart has little effect on force of contraction because the vagus nerve does not supply most of the ventricular myocytes.

True

The sympathetic impulses increase heart rate and contraction force while parasympathetic impulses decrease heart rate.

True

Which of the following statements is false in reference to heart regulation?

baroreceptors measure the amount of sodium ions present in the blood

The amount of blood ejected from either ventricle every minute is called:

cardiac output

The formula for calculating cardiac output (CO) is

heart rate multiplied by stroke volume

Stroke volume is increased by

increased preload, decreased afterload, increased contractility (see animation)

Hypertension

increases aortic pressure (see animation)

Prior to physical activity, the heart rate may climb. This anticipatory increase is caused by nerve impulses traveling to the cardiovascular center of the medulla oblongata that originate in the

limbic system

Stimulation of which nerve reduces heart rate?

vagus nerve