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Reabsorption and Secretion Along the Loop of Henle - Anatomy & Physiology (view source)
Revision as of 10:34, 4 September 2008
, 10:34, 4 September 2008no edit summary
When there is excess water in the body the excess fluid passes through the loop of henle because the fluid entering the loop is less concentrated already the solutes only have so much osmotic potential and therefore are unable to draw the excess water from the lumen. This contributes to allowing the kidneys to produce dilute urine.
When there is excess water in the body the excess fluid passes through the loop of henle because the fluid entering the loop is less concentrated already the solutes only have so much osmotic potential and therefore are unable to draw the excess water from the lumen. This contributes to allowing the kidneys to produce dilute urine.
==Vasa Recta Physiology==
Water salts and urea can pass freely across the capillary walls of the vasa recta and therefore as the vessels reach deeper into the medulla where the interstitum surrounding them becomes more hypertonic the blood inside them in turn becomes more hypertonic. As the blood ascends back out of the medulla the osmolarity reduces until it is only slightly higher than when it entered. The conclusion drawn from this is that the solutes which are reabsorbed from the fluid mainly remain in the surrounding tissue and maintain the concentration gradient. If the system was not arranged in loops then this would not be possible. Although the blood leaving the medulla is always slighty more concentrated than when it entered upon reaching the cortex, if the urine being produced is very concentrated, it actually becomes hypo osmolar as more water than salt is being reabsorbed in the distal tubules which reside in there. Overall the osmolarity of the blood decreases when concentrated urine is being produced and increased when dilute urine is being produced.