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Reabsorption and Secretion Along the Distal Tubule and Collecting Duct - Anatomy & Physiology (view source)
Revision as of 13:30, 4 September 2008
, 13:30, 4 September 2008→Ions and Compounds
=====Intercalated Cells of Collecting Duct=====
=====Intercalated Cells of Collecting Duct=====
* Potassium is absorbed here in exchange for hydrogen
* Potassium is absorbed here in exchange for hydrogen
===Urea===
In the lower portion of the collecting duct urea freely diffuses across the epithelia. The permeability is also increased with ADH. This adds to the hypertonicity of the medulla and increases water reabsorption.
=====Urea and Water Reabsorption=====
Water follows urea as it is reabsorbed from the collecting duct. This actually increases the concentration of urea in the tubular fluid despite some of it being reabsorbed. This means that urea concentration only drops moderately when the urine concentration falls due to increased reabsorption of water.