A birth defect called transposition of great vessels results in the pulmonary trunk emanating from the left ventricle and the aorta stemming from the right ventricle.

Which ventricle is thicker-walled, and why?

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?

A newer drug, ivabradine, lowers the heart rate by blocking the nonselective HCN cation channels. Why would this action decrease the heart rate? Would this drug have an effect on pacemaker cells, contractile cells, or both? Explain.

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?

An experimental toxin makes the refractory period of cardiac muscle cells equal in length to that of skeletal muscle fibers. Predict the consequences of this toxin.

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.

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

The heart plays a role in the regulation of blood pressure and secretes the hormone atrial natriuretic peptide.

The pericardial cavity is located between:

a. The parietal pericardium and the fibrous pericardium.

b. The fibrous pericardium and the myocardium.

c. The parietal pericardium and the visceral pericardium.

d. The epicardium and the endocardium.

Which of the following statements is true?

a. The tricuspid valve is located between the right atrium and the right ventricle.

b. The mitral valve is located between the pulmonary veins and the left atrium.

c. The pulmonary valve is located between the pulmonary artery and the pulmonary veins.

d. The aortic valve is located between the right ventricle and the aorta.

How do pacemaker cardiac muscle cells differ from contractile cardiac muscle cells? What is autorhythmicity?

Cardiac muscle cells are joined by structures called:

a. T-tubules.

b. tight junctions.

c. sarcoplasmic reticulum.

d. intercalated discs.

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

The rapid depolarization phase of the contractile cell action potential is due to the opening of voltage-gated potassium ion channels.

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

Pacemaker cells lack a distinct plateau phase.

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

The plateau phase in contractile cells is due to the influx of calcium ions through calcium ion channels.

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

Open sodium ion channels cause hyperpolarization in pacemaker cells, which triggers HCN channels to open and begins a new action potential.

What are the effects of the plateau phase of the contractile cell action potential?

The ______ is the primary pacemaker of the heart.

a. Atrioventricular node

b. sinoatrial node

c. Purkinje fiber system

d. Atrioventricular bundle

Explain what each of the following terms represents on an electrocardiogram (ECG).

a. P wave

b. QRS complex

c. T wave

d. P-R interval

e. S-T segment

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.

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

Atrial systole is responsible for ejecting most of the blood into the ventricles during the ventricular filling phase of the cardiac cycle.

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

The amount of blood in the ventricles at the end of the ventricular filling phase is the end-systolic volume.

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

The ventricular ejection phase generally correlates with the S-T segment and the T wave on the ECG.

Which chamber generates the highest pressure during systole?

a. Right atrium

b. Right ventricle

c. Left atrium

d. Left ventricle

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

Tissue perfusion to the heart decreases during systole and increases during diastole.

The first heart sound is called ________ and it is caused by the closing of the ________ valves. It occurs at the beginning of the ________ phase of the cardiac cycle. The second heart sound is called ________ and it is caused by the closing of the ________ valves. It occurs at the beginning of the ________ phase of the cardiac cycle.

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.

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.