Question:medium
In hypovolemic shock, which of the following renal vascular changes occurs?
In hypovolemic shock, which of the following renal vascular changes occurs?
Show Hint
Sympathetic and angiotensin surge clamps the inflow arteriole to the glomerulus.
Updated On: Jun 23, 2026
- Afferent arteriolar constriction
- Efferent arteriolar constriction
- Increased blood flow to kidney
- Normal cardiac output
Show Solution
The Correct Option is A
Solution and Explanation
Step 1: Start from the central problem in hypovolemic shock - the tank is empty, so venous return, stroke volume, and cardiac output all drop.
Step 2: Baroreceptor unloading triggers a massive sympathetic surge plus activation of renin-angiotensin. The aim is to defend perfusion of the brain and heart by clamping down everywhere else, raising systemic vascular resistance.
Step 3: Within the renal circulation this intense catecholamine drive constricts the afferent arteriole, cutting renal blood flow and protecting the rest of the circulation - the limbs go cold and shut down.
Step 4: Rule out the alternatives: renal flow goes down not up, cardiac output is depressed rather than normal, and isolated efferent constriction is the GFR-sparing mechanism of moderate hypovolemia, not the hallmark of established shock. \[\boxed{\text{Afferent arteriolar constriction}}\]
Step 2: Baroreceptor unloading triggers a massive sympathetic surge plus activation of renin-angiotensin. The aim is to defend perfusion of the brain and heart by clamping down everywhere else, raising systemic vascular resistance.
Step 3: Within the renal circulation this intense catecholamine drive constricts the afferent arteriole, cutting renal blood flow and protecting the rest of the circulation - the limbs go cold and shut down.
Step 4: Rule out the alternatives: renal flow goes down not up, cardiac output is depressed rather than normal, and isolated efferent constriction is the GFR-sparing mechanism of moderate hypovolemia, not the hallmark of established shock. \[\boxed{\text{Afferent arteriolar constriction}}\]
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