Talk:Thin ascending limb of loop of Henle
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I always thought that sodium was actively transported out of the ascending loop. Because the concentration outside would have to be high so the water potential is low enough for sufficient reapsorbtion from the descending loop.
Am I misinformed? or should it be changed. Thanks Robbos Jan 8, 2007 (UTC)
Yes, you are right and it should be changed. A couple of points:
1) At every point along the ascending limb, the osmolality of the (medullary) interstitium is higher than that of the tubular fluid. So, nowhere along the length of the ascending limb is there a concentration gradient that would favor the passive diffusion of sodium from the lumen into the interstitium. (In the case of the descending loop, the lumenal fluid is isosmotic w.r.t to the interstitium — that is, it increases it descends — due to the water permeability of the tubular epithelium). Anyway, the article is incorrect about sodium.
2) You are right that sodium is transported out of the ascending loop. My renal phys book describes the sodium transport mechanisms for the thick segment, but says of the thin segment only that its mechanisms are still poorly understood. However, this is a 1994 book — Vander (Lange series) 5th edition. Maybe it's better understood now, I don't know.
Correct me if I'm wrong, but doesn't active transport of chloride ions in the thin ascending loop drive *passive diffusion* of sodium ions (because of ion attraction)? CrocodilesAreForWimps (talk) 18:41, 30 July 2012 (UTC)
Contradiction within intro / cleanup
Somebody wrote "(NO!..." in the article body. Contradiction doesn't seem to be properly resolved. Also citation improperly done.
- This article is hilarious because it argues with itself. Made me laugh haha. The ending person I think is right btw. I think the key is: Water is "lost" at the loop of Henle (not sure about reabsorbed, it could be too...) 22.214.171.124 (talk) 11:32, 22 October 2012 (UTC)
Not "thin" ascending limb...it's "thick" ascending limb.
Deleted contradictions without replacement. Moved arguments to this page. This page was helping no one.
I'll add that at no point along the loop is the filtrate in the loop more hypertonic than in the interstitium.
Because this segment is permeable to solutes, ions and other small particles can pass through the limb and enter the extracellular fluid (ECF) which causes the solute concentration of the ECF to rise, and thus causes the solute concentration within the loop of Henle to decrease. — Preceding unsigned comment added by 126.96.36.199 (talk) 21:19, 19 March 2013 (UTC)
(No! The loop of Henle, including the thin ascending limb, is responsible for creating the hyperosmotic medulla, but the actual reabsorption of water occurs in the collecting duct, where ADH can influence the amount of water reabsorbed depending on physiological conditions that change the need for water retention or excretion.
Yes, the main route of water reabsorption occurs in the collecting duct under the hormonal regulation of ADH, but a 3rd of water reabsorption occurs in the loop of henle. This is because the urine is being concentrated in the LOH, by means of reabsorbing water into the intersitium after countercurrent multiplication. The water that enters the interstitium then moves along its osmotic gradient into the vasa recta, which then contributes to blood volume. Therefore, water reabsorption DOES occur in the LOH. Neither mind the fact that 120 L of the 180 L filtered per day is reabsorbed in the promixal tubule.)