18. The Heart

Mark the following statements as true or false. If a statement is false, correct it to make a true statement.

Systole is the contraction portion of the cardiac cycle and diastole is the relaxation portion.

The following measurements were made on two individuals (the values recorded remained stable for 1 hour):

Person 1: heart rate, 75 bpm; stroke volume, 60 mL

Person 2: heart rate, 90 bpm; stroke volume, 95 mL

Which person has the greater venous return?

Which person has the longer ventricular filling time?

Mark the following statements as true or false. If a statement is false, correct it to make a true statement.

The heart consists of two superior ventricles and two inferior atria.

For the atrioventricular valves to be open, the pressure in the ventricles must be:

When the semilunar valves are open, which of the following are occurring?

(1) Coronary arteries fill

(2) AV valves are closed

(3) Ventricles are in systole

(4) Ventricles are in diastole

(5) Blood enters the aorta

(6) Blood enters pulmonary arteries

(7) Atria contract

a. 2, 3, 5, 6

b. 1, 2, 3, 7

c. 1, 3, 5, 6

d. 2, 4, 5, 7

Describe how heart contraction and relaxation influence coronary blood flow

Name the major branches of the coronary arteries, and note the heart regions served by each

Mr. Watson has been diagnosed with mitral insufficiency, or a malfunctioning mitral valve, which causes the valve to not close properly. Predict the signs and symptoms you might expect from a disease of this valve. What would happen to the patient's stroke volume and cardiac output? Explain. What might help improve his cardiac output?

Two elements determine blood pressure—the cardiac output of the heart and the peripheral resistance, or friction, in the blood vessels. Name two factors that increase cardiac output. Name two factors that increase peripheral resistance.

During diastole, a chamber of the heart:

(a) Relaxes and fills with blood

(b) Contracts and pushes blood into an adjacent chamber

(c) Experiences a sharp increase in pressure

(d) Reaches a pressure of approximately 120 mm Hg

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.

Discuss how the Frank-Starling law of the heart helps to explain the influence of venous return on stroke volume.

More than one choice may apply.

How many cusps does the right atrioventricular valve have?

a. Two

b. Three

c. Four

d. Six