ATI RN

1. Identify the three layers of the heart:

• A. Endocardium, Myocardium, Epicardium
• B. Epicardium, Pericardium, Endocardium
• C. Myocardium, Endocardium, Pericardium
• D. Pericardium, Myocardium, Endocardium

Correct Answer: A

Rationale: The correct answer is A: Endocardium, Myocardium, Epicardium. The heart consists of three main layers: the endocardium, which lines the inner chambers of the heart; the myocardium, the middle layer responsible for the heart's pumping action; and the epicardium, the outermost layer that protects the heart. Choices B, C, and D are incorrect as they do not list the heart's layers in the correct order or combination.

2. Which valve opens during ventricular systole and closes during ventricular diastole?

• A. Aortic valve
• B. Pulmonary valve
• C. Mitral valve
• D. Tricuspid valve

Correct Answer: B

Rationale: The correct answer is B: Pulmonary valve. The pulmonary valve opens during ventricular systole to allow blood to flow from the right ventricle into the pulmonary artery. The aortic valve opens during ventricular systole to allow blood to flow from the left ventricle into the aorta. The mitral valve and tricuspid valve are atrioventricular valves that open during ventricular diastole to allow blood to flow from the atria into the ventricles.

3. During which process does coronary artery blood flow to the myocardium occur during diastole, when coronary vascular resistance is reduced?

• A. Coronary perfusion pressure
• B. Coronary vascular resistance
• C. Diastolic filling
• D. Ventricular ejection

Correct Answer: A

Rationale: The correct answer is A: Coronary perfusion pressure. Coronary perfusion pressure refers to the process of coronary artery blood flow to the myocardium during diastole when coronary vascular resistance is reduced. This process ensures that the myocardium receives sufficient oxygen and nutrients for proper functioning. Choice B, Coronary vascular resistance, is the opposite of what is described in the question. During coronary perfusion, resistance is reduced to enhance blood flow. Choices C and D, Diastolic filling and Ventricular ejection, do not directly relate to the process of coronary artery blood flow during diastole.

4. What is the ability of cardiac cells to respond to an impulse by transmitting the impulse along cell membranes?

• A. Contractility
• B. Automaticity
• C. Conductivity
• D. Rhythmicity

Correct Answer: C

Rationale: The correct answer is C, Conductivity. Conductivity refers to the ability of cardiac cells to transmit impulses along cell membranes. Contractility (Choice A) is the ability of cardiac cells to contract in response to an electrical stimulus, not transmit impulses. Automaticity (Choice B) is the ability of cardiac cells to spontaneously generate electrical impulses. Rhythmicity (Choice D) refers to the regular generation of electrical impulses by the heart's pacemaker cells, not the transmission of impulses along cell membranes.

5. What term refers to the degree of myocardial fiber stretch before contraction, related to the volume of blood distending the ventricles at the end of diastole, and determined by the amount of venous return?

• A. Preload
• B. Afterload
• C. Contractility
• D. Ejection fraction

Correct Answer: A

Rationale: The correct answer is A: Preload. Preload is the degree of myocardial fiber stretch before contraction, influenced by the volume of blood returning to the heart. This parameter is related to the amount of blood in the ventricles at the end of diastole. Choice B, Afterload, refers to the pressure or resistance that the ventricles must overcome to eject blood. Choice C, Contractility, is the intrinsic ability of the heart muscle to contract. Choice D, Ejection fraction, is the percentage of blood pumped out of the ventricles with each contraction.