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?

Correct Answer: A

Rationale: Rationale: 1. Preload refers to myocardial fiber stretch before contraction. 2. It is related to the volume of blood in ventricles at end of diastole. 3. Preload is determined by the amount of venous return to the heart. 4. It influences the force of contraction and stroke volume. 5. Afterload (B) is the resistance the heart must overcome to pump blood. 6. Contractility (C) is the intrinsic strength of the heart muscle. 7. Ejection fraction (D) is the percentage of blood ejected from ventricles. Summary: - Preload is correct as it specifically relates to fiber stretch and volume of blood. - Afterload, contractility, and ejection fraction do not directly relate to ventricular volume and venous return.

Correct Answer: A

Rationale: The correct answer is A: Cardiogenic shock. Cardiogenic shock is characterized by decreased cardiac output and tissue perfusion due to the heart's inability to pump effectively, leading to organ failure. This condition is a result of heart failure or myocardial infarction. Myocardial infarction (choice B) is a cause of cardiogenic shock, but not the specific condition described. Endocarditis (choice C) and pericarditis (choice D) do not directly result in decreased cardiac output and tissue perfusion leading to organ failure like cardiogenic shock does.

Correct Answer: A

Rationale: The correct answer is A: Interventricular septum. This structure separates the left and right sides of the heart, forming a barrier between the two ventricles. It ensures that oxygenated and deoxygenated blood do not mix within the heart chambers. The endocardium (B) is the inner layer of the heart's chambers, the epicardium (C) is the outer layer of the heart, and the pericardium (D) is the sac surrounding the heart. These structures do not specifically separate the left and right sides of the heart.

Correct Answer: A

Rationale: The correct answer is A: Systole. During systole, the heart muscle contracts to pump blood out of the chambers. This phase is essential for delivering oxygenated blood to the body. Diastole (B) is the relaxation phase when the heart fills with blood. Contractility (C) refers to the heart's ability to contract, not a specific phase. Afterload (D) is the pressure the heart must pump against to eject blood, not a phase of the cardiac cycle. Therefore, the term that specifically refers to the contraction phase of the heart is systole.

Correct Answer: A

Rationale: Atherosclerosis is the correct answer because it specifically refers to the accumulation of fatty deposits in arteries, causing reduced blood flow. Arteriosclerosis is a general term for thickening and hardening of arteries, not necessarily due to fatty deposits. Aneurysm is a localized, abnormal dilation of a blood vessel, not related to fatty deposits. Thrombosis is the formation of a blood clot within a blood vessel, not the accumulation of fatty deposits.