In the kidney, where are the mechanisms found that are responsible for increasing urine concentration?
Calyx.
Proximal convoluted tubule.
Renal pelvis.
The loop of Henle.
The Correct Answer is D
The loop of Henle, a critical structure within the nephron of the kidney, plays a key role in the concentration of urine through the process of countercurrent multiplication. Here's why option D is the correct choice:
A) Calyx:
The calyx is a structure in the kidney that collects urine from the renal papillae and channels it into the renal pelvis. It does not directly participate in the concentration of urine.
B) Proximal convoluted tubule:
The proximal convoluted tubule primarily reabsorbs water, electrolytes, and nutrients from the glomerular filtrate, but it does not contribute significantly to the concentration of urine.
C) Renal pelvis:
The renal pelvis is a funnel-shaped structure that collects urine from the calyces and funnels it into the ureter. It is not directly involved in the concentration of urine.
D) The loop of Henle:
Correct. The loop of Henle is the nephron segment responsible for generating a hypertonic medullary interstitium, which creates the osmotic gradient necessary for urine concentration. The loop of Henle achieves this through countercurrent multiplication, where the descending limb allows passive reabsorption of water, while the ascending limb actively pumps out sodium and chloride ions. This creates an osmotic gradient that allows for further water reabsorption in the collecting ducts, leading to concentrated urine.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is C
Explanation
A) Small, skin-colored, pedunculated papules in areas of skin folds and on other areas as skin tags:
This description is more characteristic of acrochordons (skin tags), which are benign skin growths often found in skin folds. Skin tags are typically not associated with acne vulgaris.
B) Hyperpigmented areas that vary in form and color and are slightly elevated from the skin:
This description may be indicative of post-inflammatory hyperpigmentation, which can occur after resolution of acne lesions. However, it does not represent the primary pathological findings observed in acne vulgaris.
C) Hyperactive sebaceous areas forming comedones, papules, pustules on the face, neck, and upper back:
Correct. Acne vulgaris is characterized by hyperactive sebaceous glands, leading to the formation of comedones (blackheads and whiteheads), papules, and pustules. These lesions commonly occur on the face, neck, and upper back due to the high density of sebaceous glands in these areas.
D) Sharply demarcated silvery scaling plaques with underlying redness on the elbows and knees:
This description is more indicative of psoriasis, a chronic autoimmune skin condition characterized by silvery scaling plaques and inflammation. Psoriasis typically affects extensor surfaces such as the elbows and knees, rather than the areas commonly affected by acne vulgaris.
Correct Answer is C
Explanation
A) Increased preload that results in generalized peripheral edema:
This statement is incorrect. Decreased blood volume due to hemorrhage leads to decreased preload, not increased preload. Generalized peripheral edema is more commonly associated with conditions such as heart failure or kidney disease, where fluid retention leads to increased preload.
B) The lowered blood pressure results in a reduction of the heart rate:
While it's true that a decrease in blood pressure can trigger compensatory mechanisms such as an increase in heart rate (tachycardia), the specific response mentioned in this option is not entirely accurate. The primary compensatory response to hemorrhage-induced hypotension is typically an increase in heart rate, not a reduction.
C) Decreased preload that can lead to decreased cardiac output:
Correct. With decreased blood volume (preload), there is less blood returning to the heart during diastole. This leads to decreased ventricular filling and subsequently decreased stroke volume and cardiac output. Decreased cardiac output can contribute to hypotension and inadequate tissue perfusion.
D) Increased peripheral resistance resulting from poor renal perfusion:
While poor renal perfusion can trigger mechanisms to increase peripheral resistance (such as activation of the renin-angiotensin-aldosterone system), this option does not directly address the primary effect of decreased preload on cardiac output. Increased peripheral resistance alone does not adequately compensate for decreased preload to maintain cardiac output.
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