Which statement best explains why antidiuretic hormone (ADH) increases blood volume?
It promotes water reabsorption in distal tubules.
It enhances sodium retention in the loop of Henle.
It decreases renal artery blood flow.
It stimulates the adrenal cortex to release aldosterone.
The Correct Answer is A
Rationale:
A. It promotes water reabsorption in distal tubules is correct. Antidiuretic hormone (ADH), also called vasopressin, is secreted by the posterior pituitary in response to increased plasma osmolality or decreased blood volume. ADH acts primarily on the distal convoluted tubules and collecting ducts of the kidney, increasing their permeability to water by inserting aquaporin-2 channels into the tubular membranes. This allows water to move from the tubular lumen back into the bloodstream, concentrating the urine and expanding blood volume, thereby helping maintain blood pressure and plasma osmolality.
B. It enhances sodium retention in the loop of Henle is incorrect. Sodium reabsorption is primarily regulated by aldosterone, not ADH. While water follows sodium osmotic gradients, ADH’s effect on water reabsorption is independent of direct sodium regulation.
C. It decreases renal artery blood flow is incorrect. ADH does have vasoconstrictive properties via V1 receptors in high concentrations, but its primary role in normal physiology is water reabsorption, not reducing renal perfusion. Decreased renal blood flow is not the mechanism by which ADH increases blood volume.
D. It stimulates the adrenal cortex to release aldosterone is incorrect. Aldosterone secretion is primarily regulated by the renin-angiotensin-aldosterone system and plasma potassium levels, not by ADH. ADH increases blood volume directly through water retention, not indirectly via aldosterone release.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
Rationale:
A. Increase fluid intake is the primary prevention strategy for calcium-based kidney stones. Adequate hydration dilutes urine, reducing the concentration of calcium, oxalate, and other stone-forming substances. This decreases supersaturation and crystal formation in the urinary tract, significantly lowering the risk of stone development. Clients are generally advised to consume enough fluids to produce at least 2–2.5 liters of urine per day unless contraindicated.
B. Increase calcium-rich foods is incorrect as a prevention strategy. While dietary calcium in normal amounts may help bind oxalate in the gut and prevent stone formation, excessive calcium supplementation without medical guidance can increase the risk of calcium-based stones. The key is balance, not simply increasing intake.
C. Restrict protein intake may help reduce uric acid stones and decrease urinary calcium to some extent, but it is not the primary prevention measure for calcium-based stones. Over-restriction of protein can lead to nutritional deficiencies.
D. Decrease fluid intake is incorrect. Reduced fluid intake concentrates urine and increases the risk of kidney stone formation. Maintaining adequate hydration is essential for prevention of all types of stones.
Correct Answer is B
Explanation
Rationale:
A. Hypertension is incorrect. While high blood pressure is a common cardiovascular condition, it is not a direct complication of deep vein thrombosis (DVT). DVT involves clot formation in the deep veins, primarily of the lower extremities, rather than elevated arterial pressure.
B. Pulmonary embolism is correct. A major and potentially life-threatening complication of DVT is pulmonary embolism (PE). If a thrombus (blood clot) from a deep vein dislodges, it can travel through the venous system to the pulmonary arteries, obstructing blood flow to the lungs. This can cause sudden shortness of breath, chest pain, hypoxia, and even death if not promptly recognized and treated.
C. Urinary tract infection is incorrect. UTIs are infections of the urinary system and are not caused by DVT. While immobility related to DVT may increase UTI risk indirectly, it is not a direct complication.
D. Peptic ulcer disease is incorrect. Peptic ulcers involve erosions in the gastric or duodenal mucosa, typically due to Helicobacter pylori infection or NSAID use. They are unrelated to the pathophysiology of DVT.
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