Chapter 12: Heart Anatomy & Physiology

When a papillary muscle in the left ventricle ruptures, the mitral valve leaflets do not close completely, resulting in: A. acute myocardial infarction. B. aortic valve failure. C. cardiac murmur. D. systemic venous congestion.

A dysfunction of the chordae tendineae or of a papillary muscle can cause incomplete closure of an atrioventricular valve, which results in backflow of blood into the atrium and produces a murmur. If a papillary muscle in the left ventricle ruptures, the mitral valve leaflets do not close completely. Clinically, this causes acute mitral regurgitation and an audible murmur that can be auscultated with a stethoscope. (C)

Pulse pressure is the difference between systolic pressure and diastolic pressure. If the patient is volume depleted or has vasoconstriction, pulse pressure will: A. narrow. B. widen. C. remain unchanged. D. increase

A symptom of vasoconstriction is a narrowed pulse pressure. A widened pulse pressure is associated with vasodilation. Cognitive Level: Comprehension Nursing Process: Assessment Client Need: Health Promotion and Maintenance (A)

What part of the arterial system contains the greatest amount of elastin? A. Aorta B. Pulmonary artery C. Common carotids D. Arterioles

The aorta contains the greatest amount of elastic tissue. This is necessary because of the sudden shifts in pressure created by the left ventricle. (A)

The structure of the microcirculation that allows for solute diffusion across the endothelium is the: A. arteriole. B. venule. C. capillary. D. precapillary sphincter.

The capillary consists of a single cell layer of endothelium and is devoid of muscle and elastin. This arrangement allows solutes to diffuse in and out of the capillaries unimpeded by mechanical barriers. Capillaries normally retain large structures, such as red blood cells, but are highly permeable to smaller solutes, such as electrolytes. (C)

A physiologic cardiac shunt occurs when there is mixing of deoxygenated blood (usually venous blood with reduced oxygen content) with arterial oxygenated blood. In the heart, this is demonstrated by: A. atrial septal defect. B. patent foramen ovale. C. thebesian veins. D. ventricular septal defect.

The thebesian veins are small vessels that connect capillary beds directly with the cardiac chambers via irregular endothelium-lined sinuses within the myocardium. The thebesian veins add a small quantity of deoxygenated blood to the oxygenated blood in the left ventricle. (C)

The time from the beginning of the cardiac action potential (AP) until the time when the fiber can accept another AP is called the: A. excitability period. B. depolarization period. C. relative refractory period. D. absolute refractory period.

The time from the beginning of the AP until the fiber can accept another AP is called the effective or absolute refractory period. During this period, the cell cannot be depolarized regardless of the amount or intensity of the stimulus. (D)

The nurse auscultates a murmur at the fifth intercostal space at the midclavicular line on the left side. The nurse realizes that this is caused by which incompetent heart valve? A. Aortic B. Pulmonic C. Mitral D. Tricuspid

This is the correct location of the mitral valve. The aortic valve is located at the second right intercostal space at the right sternal border. The pulmonic valve is located at the second left intercostal space at the left sternal border. The tricuspid valve is located at the fourth left intercostal space at the left sternal border. Cognitive Level: Comprehension Nursing Process: Assessment Client Need: Physiological Integrity: Reduction of Risk Potential (C)

An important intracellular structure, essential for cardiac contraction, that stores calcium ions for release and use after depolarization is the: A. sarcoplasmic reticulum. B. sarcomere. C. sarcolemma. D. transverse tubules.

An extremely important intracellular structure that is necessary for successful contraction is the sarcoplasmic reticulum. Calcium ions are stored in the sarcoplasmic reticulum and released for use after depolarization. (A)

Aortic valve dysfunction pathologically alters the: A. left atrium. B. left ventricle. C. right ventricle. D. mitral valve.

Aortic valve dysfunction from any cause not only affects the valve leaflets but also pathologically alters the shape of the left ventricle. (B)

Cardiac output is the amount of blood ejected from the heart in 1 minute. If the heart rate (HR) is 72 beats/min and stroke volume (SV) is 70 mL/beat, cardiac output is: A. 2 L/min. B. 5.04 L/min. C. 142 L/min. D. 120 L/min.

Cardiac output is HR × SV = 70 × 72 beats/min × 70 mL/beats = 5040 mL/min = 5.04 L/min. Cognitive Level: Analysis Nursing Process: Assessment Client Need: Health Promotion and Maintenance (B)

In an effort to improve cardiac output, a positive inotropic drug is given to: A. increase the contractility of the heart. B. increase the heart rate. C. increase the conduction velocity. D. increase the automaticity of the heart.

Positive inotropic drugs increase the force of contraction of the heart to improve cardiac output. A drug that increases heart rate would be a positive chronotrope. A drug that increases conduction velocity would speed conduction from the SA to the AV node, and a drug that increases automaticity would stimulate electrical impulses. Cognitive Level: Comprehension Nursing Process: Evaluation Client Need: Physiological Integrity: Pharmacological and Parenteral Therapies (A)

The volume of blood in the left ventricle at the end of diastole is best described as: A. afterload. B. stroke volume. C. preload. D. contractility.

Preload is the volume of blood in the left ventricle at the end of diastole. Contractility refers to the heart's contractile force. Afterload can be defined as the ventricular wall tension or stress during systolic ejection. (C)

The nurse is explaining the function of the AV node to the student nurse. Which statement is true? (Select all that apply.) A. The conduction time of impulses from the SA to the AV node allows the ventricles to fill with blood during diastole. B. The AV node prevents rapid heart rates from destabilizing the heart. C. The AV node provides a backup pacemaker if the SA node fails. D. The AV node sends impulses forward only. E. The AV is located on the left side of the interatrial septum

The conduction time of impulses from the SA to the AV node allows the ventricles to fill with blood during diastole, the AV node prevents rapid heart rates from destabilizing the heart, and the AV node provides a backup pacemaker if the SA node fail are all true statements about the function of the AV node. The AV node conducts impulses forward and backward (retrograde) and is located on the right side of the interatrial septum. Cognitive Level: Comprehension Nursing Process: Assessment Client Need: Health Promotion and Maintenance (A, B, C)

A patient is reported to have an ejection fraction of 30%. What is this finding most likely a sign of? A. Coronary artery disease B. Ventricular dysrhythmia C. Pulmonic valve regurgitation D. Poor ventricular function

The ejection fraction (EF) is the ratio of the stroke volume ejected from the left ventricle per beat to the volume of blood remaining in the left ventricle at the end of diastole. EF is expressed as a percentage, and a normal value is 50% or greater. An EF of less than 35% indicates poor ventricular function (as in cardiomyopathy), poor ventricular filling, obstruction to outflow (as in some valve stenosis conditions), or a combination of these conditions. (D)

In regard to cardiac action potential, phase 3 is best described as: A. rapid depolarization, opening of the fast Na+ channels and causing a rapid influx of Na+ ions. B. resting membrane potential; excess Na+ that entered the cell is removed from the cell in exchange for K+ by means of the Na+/K+ pump. C. partial repolarization, as the action potential returns toward zero, when the rapid influx of Na+ is terminated. D. repolarization, preventing further influx of Ca2+/Na+ while promoting efflux of K+ out of the cell.

The repolarization phase is described as phase 3, and it depends on two processes. The first is the inactivation of the slow channels, which prevents further influx of Ca2+ and Na+. The other is the continued efflux of K+ out of the cell. (D)

Which myocardial structure is supplied by the left anterior descending artery? A. Sinus node B. Intraventricular septum C. Posterior wall D. AV node

The right coronary artery (RCA) serves the right atrium and the right ventricle in most people. In 63% of the population, the sinus node artery arises from the RCA. The AV node is supplied via the RCA in 90% of the population. The term dominant coronary artery is used to describe the artery that supplies the posterior part of heart. In most of the population, the RCA is dominant, supplying the posterior cardiac wall. The left anterior descending (LAD) artery and the circumflex artery serve the left atrium and most of the left ventricle. The LAD provides blood supply to the intraventricular septum via septal perforator branches. (B)