ATI RN

1. Which heart chamber ejects blood into the systemic arterial circulation via the aorta?

• A. Right atrium
• B. Left atrium
• C. Right ventricle
• D. Left ventricle

Correct Answer: D

Rationale: The correct answer is D, Left ventricle. The left ventricle pumps oxygenated blood into the systemic circulation via the aorta. This chamber receives oxygen-rich blood from the left atrium and contracts forcefully to propel blood into the aorta, distributing it to the body. The other options, right atrium, left atrium, and right ventricle, do not directly eject blood into the systemic arterial circulation via the aorta. The right atrium receives deoxygenated blood from the body, the left atrium receives oxygenated blood from the lungs, and the right ventricle pumps blood to the lungs for oxygenation.

2. Which artery supplies the anterior wall of the left ventricle, the anterior interventricular septum, the anterior papillary muscles, and apex of the heart?

• A. Left anterior descending artery
• B. Left circumflex artery
• C. Posterior descending artery
• D. Aortic artery

Correct Answer: A

Rationale: The correct answer is the Left anterior descending artery. This artery supplies the anterior wall of the left ventricle, the anterior interventricular septum, the anterior papillary muscles, and apex of the heart. The Left circumflex artery (choice B) supplies the lateral and posterior walls of the left ventricle, the posterior descending artery (choice C) supplies the inferior part of the heart, and the aortic artery (choice D) is not a specific coronary artery.

3. Which term refers to the ability of the heart to initiate impulses repetitively and spontaneously?

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

Correct Answer: C

Rationale: The correct answer is C: Automaticity. Automaticity is the specific term used to describe the heart's ability to generate impulses repetitively and spontaneously. Contractility (A) refers to the ability of muscle fibers to contract, not the initiation of impulses. Excitability (B) is the ability of cells to respond to stimuli but is not specific to the heart's impulse generation. Rhythmicity (D) is a related term but does not specifically describe the heart's spontaneous impulse initiation.

4. What is the term for the amount of blood ejected by the left ventricle into the aorta per beat, determined by preload, contractility, and afterload?

• A. Stroke volume
• B. Cardiac output
• C. End-diastolic volume
• D. Ejection fraction

Correct Answer: A

Rationale: The correct answer is A: Stroke volume. Stroke volume refers to the volume of blood ejected by the left ventricle during each heartbeat. This is determined by preload (the degree of stretch of the cardiac muscle fibers at the end of diastole), contractility (the force of myocardial contraction), and afterload (the pressure or resistance that the ventricle must overcome to eject blood). Choice B, Cardiac output, is the volume of blood pumped by the heart per minute and is calculated by multiplying the heart rate by the stroke volume. Choice C, End-diastolic volume, is the volume of blood in the ventricle at the end of diastole before contraction. Choice D, Ejection fraction, is the proportion of blood pumped out of the ventricle with each contraction, calculated by dividing the stroke volume by the end-diastolic volume.

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

• A. Norepinephrine
• B. Epinephrine
• C. Dopamine
• D. Acetylcholine

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.