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Basic Renal Processes for Sodium, Chloride, and Water
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Chloride reabsorption parallels sodium reabsorption mainly because:
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a. most chloride transport is via a symporter with sodium.
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b. chloride is the most abundant negatively charged species available to balance the reabsorption of the positive charge on sodium.
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c. chloride has such a high passive permeability.
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d. chloride and sodium are both part of the sodium chloride molecule and cannot be separated.
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B. Reabsorbed sodium must be balanced by reabsorbed anions. Once most of the bicarbonate is reabsorbed, only chloride exists in high enough concentration to match the continued reabsorption of sodium.
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The obligatory water loss in the kidney:
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a. is another name for insensible loss of water.
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b. occurs because there is always at least some excretion of waste solutes.
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c. occurs because there is an upper limit to how fast aquaporins can reabsorb water.
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d. is the amount of water that accompanies sodium excretion.
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B. So long as there is filtration there is excretion of organic waste which obligates water to be excreted also.
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Which region of the tubule secretes water?
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a. The descending thin limb.
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b. The cortical collecting duct.
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c. The medullary collecting duct (when ADH is absent).
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d. No region secretes water.
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D. Osmotic conditions in all tubule regions favor water reabsorption.
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If the thick ascending limb stopped reabsorbing sodium, then the final urine would be:
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a. iso-osmotic with plasma in all conditions.
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d. dilute or concentrated, depending on ADH.
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A. The tubular fluid entering the medulla is iso-osmotic. If the tubules did not separate salt from water, the medullary interstitium would remain iso-osmotic. The luminal fluid would also remain iso-osmotic because there would be no osmotic gradient to either dilute it or concentrate it.
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If a healthy young person drinks a large amount of water, which of the following is unlikely to happen?
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