this refers to a change in the inotropic state of the muscle without a change in myocardial fiber length
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ATI RN

Cardiovascular System Exam

1. This term refers to a change in the inotropic state of the muscle without a change in myocardial fiber length.

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.

2. Which neurotransmitter is released by the sympathetic nervous system (SNS) to increase heart rate and the force of contraction of the heart?

Correct answer: A

Rationale: The correct answer is Norepinephrine. Norepinephrine is the neurotransmitter released by the sympathetic nervous system that increases heart rate and the force of contraction. Epinephrine, though similar, is more involved in the fight-or-flight response and has a broader range of effects on various organs. Dopamine is not primarily responsible for increasing heart rate and contractility. Acetylcholine is a neurotransmitter that predominantly acts on the parasympathetic nervous system to decrease heart rate and contractility.

3. This is a more accurate indicator of tissue perfusion. It represents the cardiac output in terms of liters per minute per square meter of body surface area. Its normal range is 2.4-4 L/min.

Correct answer: A

Rationale: The correct answer is A: Cardiac Index. Cardiac Index is a measure of cardiac output relative to body surface area, providing a more accurate assessment of tissue perfusion. It is calculated by dividing the cardiac output by the body surface area. The normal range for cardiac index is 2.4-4 L/min/m². Choice B, Stroke volume, refers to the amount of blood ejected by the heart in one contraction and is not adjusted for body surface area. Choice C, Ejection fraction, is the percentage of blood pumped out of the heart's ventricles with each contraction, not adjusted for body surface area. Choice D, Cardiac output, is the total volume of blood pumped by the heart per minute, without considering body surface area.

4. What is this surgical procedure that restores blood flow to the heart by diverting blood around a blocked artery?

Correct answer: A

Rationale: The correct answer is A, Coronary artery bypass graft (CABG), which is a surgical procedure to improve blood flow to the heart by redirecting blood around blocked or narrowed arteries. This procedure is specifically designed to bypass blocked coronary arteries, allowing blood to flow more freely to the heart muscle. Choices B, C, and D are incorrect because angioplasty involves opening up narrowed or blocked blood vessels, stent placement involves inserting a mesh tube to keep arteries open, and valve replacement involves replacing a damaged heart valve - none of which directly address diverting blood flow around a blocked artery.

5. Which medication relaxes the muscles around the airways, making it easier to breathe?

Correct answer: A

Rationale: The correct answer is A, Bronchodilator. Bronchodilators are medications that relax the muscles surrounding the airways, which helps to open them and makes breathing easier. Corticosteroids (choice B) work by reducing inflammation, antihistamines (choice C) are used to manage allergies, and mucolytics (choice D) help to break down and thin mucus in the airways.

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