WBR0420
| Author | [[PageAuthor::Rim Halaby, M.D. [1], Alison Leibowitz [2] (Reviewed by Alison Leibowitz)]] |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Physiology |
| Sub Category | SubCategory::Renal |
| Prompt | [[Prompt::A researcher, studying the fate of bile salts following release into the gastrointestinal tract, notes that after filtration, at the level of the kidney, the amount of bile salts within one of the nephron segments increases rapidly. Based on the image below, which of the following nephron segments is most likely responsible for the secretion of bile salts?
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| Answer A | AnswerA::A |
| Answer A Explanation | AnswerAExp::See explanation. |
| Answer B | AnswerB::B |
| Answer B Explanation | [[AnswerBExp::The thin descending segment of loop of Henle, with thin epithelial membranes lacking brush borders, is not the major site of bile salt secretion. Because few mitochondria are located in this site of nephron, it is considered a segment with minimal metabolic activity.]] |
| Answer C | AnswerC::C |
| Answer C Explanation | [[AnswerCExp::The thick ascending loop of Henle, which has thick epithelial cells with high metabolic activity, is not the major site of bile salt secretion. The reabsorption of crucial ions, such as sodium, potassium, and chloride, occurs at the thick ascending loop of Henle.]] |
| Answer D | AnswerD::D |
| Answer D Explanation | AnswerDExp::The distal tubule, with a reabsorptive capacity similar to that of the thick ascending loop of Henle, is not the major site of bile salt secretion. The functional characteristics resemble those of the cortical collecting tubule. |
| Answer E | AnswerE::E |
| Answer E Explanation | AnswerEExp::The collecting duct is not the major site of bile salt secretion. Collecting tubules contain principal cells and intercalated cells. |
| Right Answer | RightAnswer::A |
| Explanation | [[Explanation::The proximal tubule, the nephron segment responsible for secretion of organic acids and bases, secretes bile salts, oxalate, urate, and catecholamines. Both filtration and secretion of these compounds play an important role in their renal excretion.
The proximal tubule is a site of major metabolic activity with numerous mitochondria. |
| Approved | Approved::Yes |
| Keyword | WBRKeyword::loop of Henle, WBRKeyword::kidney, WBRKeyword::bile salts, WBRKeyword::proximal tubule, WBRKeyword::nephron, WBRKeyword::secretion, WBRKeyword::metabolic |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |
