Cardiovascular System Exam

Correct Answer: A

Rationale: The correct answer is A: Contractility. Contractility specifically refers to the change in the force of contraction of the heart muscle without changing its length. In this scenario, the focus is on the change in the inotropic state of the muscle, which directly relates to contractility. Choice B, Excitability, refers to the ability of a cell to respond to a stimulus, not specifically related to changes in contractile force. Choice C, Refractoriness, pertains to the period during which a cell is unresponsive to a new stimulus. Choice D, Automaticity, refers to the ability of cardiac cells to spontaneously generate electrical impulses.

Correct Answer: A

Rationale: The correct answer is A: Coronary artery bypass graft (CABG). This surgical procedure is used to redirect blood flow around a blocked or narrowed artery by using a graft from another part of the body. Choices B, C, and D are incorrect because valve replacement involves replacing heart valves, aneurysm repair addresses the treatment of aneurysms, and atherectomy is a procedure to remove plaque from blood vessels, none of which match the description provided in the question.

Correct Answer: A

Rationale: Hypertrophic cardiomyopathy is the correct answer. It is a condition characterized by the abnormal thickening of the heart muscle without an obvious cause, which impairs the heart's ability to effectively pump blood. Dilated cardiomyopathy (choice B) involves the enlargement and weakening of the heart chambers, not thickening. Restrictive cardiomyopathy (choice C) refers to the stiffening of the heart muscle, limiting its ability to fill properly. Myocarditis (choice D) is inflammation of the heart muscle usually caused by a viral infection, not thickening.

Correct Answer: B

Rationale: In cases of myocardial infarction leading to shock, dopamine is the drug of choice. Dopamine helps increase blood pressure and improve blood flow to vital organs, making it beneficial in managing shock. Atropine is mainly used for symptomatic bradycardia, not for shock. Digoxin is a cardiac glycoside used in heart failure and atrial fibrillation, not for managing shock. Adenosine is typically used for diagnosing and treating supraventricular tachycardias, not for shock associated with myocardial infarction.

Correct Answer: B

Rationale: The correct answer is B: Atrioventricular Valves. The atrioventricular (AV) valves, including the mitral valve and tricuspid valve, close during ventricular systole to prevent backflow of blood from the ventricles into the atria. They open during ventricular diastole to allow blood flow from the atria into the ventricles. Semilunar valves, choice A, are located at the exits of the ventricles and prevent backflow into the ventricles. The mitral valve and tricuspid valve, choices C and D, are specific types of AV valves.