What is the ability of cardiac cells to respond to an impulse by transmitting the impulse along cell membranes?

Correct Answer: C

Rationale: The correct answer is C: Conductivity. Cardiac cells have the ability to transmit impulses along cell membranes, allowing for the coordinated contraction of the heart. Conductivity refers to this specific property of cardiac cells to propagate electrical signals. Contractility (A) refers to the ability of cardiac muscle cells to generate force during contraction. Automaticity (B) refers to the ability of cardiac cells to spontaneously generate electrical impulses. Rhythmicity (D) refers to the regularity of these electrical impulses in the heart. Conductivity is the most relevant choice as it directly addresses the transmission of impulses along cell membranes in cardiac cells.

Correct Answer: A

Rationale: The correct answer is A: Baroreflex. The baroreflex is a physiological mechanism that helps regulate blood pressure by responding to changes in pressure. When blood pressure decreases, the baroreceptors detect this change and trigger a sympathetic nervous system (SNS) response, leading to increased heart rate, contractility, and vasoconstriction to raise blood pressure. Conversely, when blood pressure increases, the baroreceptors trigger a parasympathetic (vagal) response, resulting in decreased heart rate and vasodilation to lower blood pressure. Summary of other choices: B: Cheyne-Stokes breathing is a pattern of breathing characterized by periodic waxing and waning of tidal volume. C: Frank-Starling Law describes the relationship between preload and stroke volume, not the response to changes in blood pressure. D: Starling reflex is not a recognized physiological mechanism related to blood pressure regulation.

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.