In heart failure, to compensate for decreased CO, the RAAS system does which of the following? Select all that apply.
Increases vasodilation
Increased blood pressure
Increases heart rate
Increases water retention
Increases respirations
Correct Answer : B,C,D
A. Increases vasodilation: The renin-angiotensin-aldosterone system (RAAS) primarily promotes vasoconstriction via angiotensin II to maintain perfusion pressure. It does not cause vasodilation; therefore, this is not a compensatory mechanism in heart failure.
B. Increased blood pressure: Activation of RAAS leads to angiotensin II–mediated vasoconstriction and aldosterone-mediated sodium retention, both of which increase systemic vascular resistance and blood pressure. This helps maintain perfusion to vital organs despite reduced cardiac output.
C. Increases heart rate: RAAS indirectly increases heart rate by promoting sympathetic nervous system activation. Elevated angiotensin II levels stimulate catecholamine release, contributing to tachycardia as a compensatory mechanism to maintain cardiac output.
D. Increases water retention: Aldosterone released by the adrenal cortex in response to RAAS activation enhances sodium and water reabsorption in the kidneys. This increases intravascular volume, which can help raise preload and temporarily improve stroke volume, though excessive retention may worsen edema.
E. Increases respirations: RAAS does not directly influence respiratory rate. Increased respirations in heart failure typically result from pulmonary congestion or hypoxia, not from RAAS activation.
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Related Questions
Correct Answer is C
Explanation
A. Contractile force increases to compensate for the reduced cardiac output: In early compensatory phases, the heart may attempt to increase contractility via sympathetic stimulation, but in true heart failure, the myocardium is unable to generate sufficient force due to structural or functional impairment.
B. Contractile force increases, leading to an increased end systolic volume: Increased contractility would reduce, not increase, end-systolic volume because more blood is ejected per beat. In heart failure, contractile weakness leads to higher end-systolic volumes, reflecting incomplete emptying of the ventricles.
C. Contractile force is diminished due to damaged cardiomyocytes or cardiomyopathies: Heart failure results from conditions such as myocardial infarction, chronic hypertension, or dilated cardiomyopathy that impair cardiomyocyte function. This reduces the strength of ventricular contraction, decreasing stroke volume and overall cardiac output.
D. Contractile force is not affected in heart failure: Contractile force is significantly affected in heart failure. The weakened myocardium cannot generate sufficient pressure to maintain normal stroke volume, making this statement inaccurate.
E. Contractile force remains the same, but the heart becomes larger: While ventricular dilation can occur in chronic heart failure as a compensatory mechanism (eccentric hypertrophy), the contractile force per myocyte is reduced. Increased chamber size alone does not preserve effective contraction.
Correct Answer is {"dropdown-group-1":"A"}
Explanation
Correct answer: Tricuspid
The tricuspid valve is located between the right atrium and the right ventricle of the heart. It consists of three cusps that open to allow blood to flow from the right atrium into the right ventricle during diastole. During ventricular contraction (systole), the tricuspid valve closes, preventing the backflow of blood into the right atrium and ensuring that blood is efficiently pumped into the pulmonary artery through the pulmonary valve. Its anatomical position and function are essential for maintaining unidirectional blood flow within the right side of the heart and supporting effective pulmonary circulation.
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