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

Correct Answer: A

Rationale: The correct answer is A: Left anterior descending artery. This artery supplies the structures mentioned due to its location and distribution in the heart. The left anterior descending artery runs along the anterior interventricular groove and provides blood flow to the anterior wall of the left ventricle, anterior interventricular septum, anterior papillary muscles, and apex of the heart. The other choices are incorrect because: B: Left circumflex artery supplies the lateral and posterior walls of the left ventricle. C: Posterior descending artery supplies the inferior part of the heart. D: Aortic artery is not a specific artery that supplies the mentioned structures.

Correct Answer: A

Rationale: The correct answer is A: Stroke volume. Stroke volume is the amount of blood ejected by the left ventricle into the aorta per beat. Preload (end-diastolic volume), contractility, and afterload influence stroke volume. Cardiac output (B) is the total volume of blood pumped by the heart per minute. End-diastolic volume (C) is the volume of blood in the ventricle before contraction. Ejection fraction (D) is the percentage of blood ejected from the ventricle during systole.

Correct Answer: A

Rationale: The correct answer is A: Norepinephrine. Norepinephrine is released by the sympathetic nervous system (SNS) to increase heart rate and the force of contraction. This neurotransmitter acts on beta-1 adrenergic receptors in the heart, leading to these effects. Epinephrine (choice B) is also released by the SNS and acts similarly to norepinephrine but is not as specific for the heart's beta-1 receptors. Dopamine (choice C) primarily acts as a precursor to norepinephrine and epinephrine and does not directly increase heart rate or force of contraction. Acetylcholine (choice D) is released by the parasympathetic nervous system and decreases heart rate and the force of contraction.

Correct Answer: A

Rationale: The correct answer is A: Cardiac Index. Cardiac Index is a more accurate indicator of tissue perfusion as it takes into account the individual's body surface area, providing a more standardized measure. It is calculated by dividing the cardiac output by body surface area. This normalization allows for a more precise assessment of tissue perfusion compared to just cardiac output alone. The normal range of Cardiac Index is 2.4-4 L/min/m^2. Summary: - Choice B (Stroke volume) is incorrect because it is the volume of blood pumped out by the heart with each heartbeat, not accounting for body surface area. - Choice C (Ejection fraction) is incorrect because it is the percentage of blood ejected from the heart's left ventricle with each heartbeat, not adjusted for body surface area. - Choice D (Cardiac output) is incorrect because it doesn't consider the individual's body surface area, making it less accurate in assessing tissue perfusion.

Correct Answer: A

Rationale: The correct answer is A: Aortic valve. The aortic valve is located between the left ventricle and the aorta, preventing the backflow of blood into the left ventricle during diastole. This is essential for maintaining proper blood flow direction and preventing regurgitation. The other choices, B: Mitral valve, C: Tricuspid valve, and D: Pulmonary valve, are all located in different areas of the heart and serve different functions. The mitral valve is between the left atrium and ventricle, the tricuspid valve is between the right atrium and ventricle, and the pulmonary valve is between the right ventricle and pulmonary artery. None of these valves are responsible for preventing backflow into the left ventricle from the aorta.