A doctor puts his stethoscope on a patient's chest over the location of the heart and hears an abnormal swishing sound. Which of the following conditions is the best diagnosis for the patient's condition?

Cardiac output is equal to:

a. end-diastolic volume minus end-systolic volume.

b. heart rate multiplied by stroke volume.

c. stroke volume divided by end-diastolic volume.

d. heart rate multiplied by preload.

Fill in the blanks: An increase in preload causes a/an_____ in stroke volume in accordance with the_____ law. An increase in afterload causes a/an ______in stroke volume. An increase in contractility causes a/an______in stroke volume.

Which of the following statements is false?

a. The sympathetic nervous system releases epinephrine and norepinephrine, which are positive chronotropic and inotropic agents.

b. The endocrine system regulates cardiac output through chronotropic and inotropic hormones and through hormones that regulate water balance.

c. The parasympathetic nervous system releases acetylcholine and epinephrine, which are strongly negative inotropic agents.

d. Factors such as electrolyte concentrations, body temperature, and age all affect cardiac output.

You are an athletic trainer who is working with someone planning to run a marathon. Your trainee tells you to give him a workout that will make his heart 'beat faster than ever before.' What do you tell him about the effects of too rapid a heart rate?