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Reabsorption and Secretion Along the Distal Tubule and Collecting Duct - Anatomy & Physiology (view source)
Revision as of 15:07, 3 September 2008
, 15:07, 3 September 2008no edit summary
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==Distal Tubule==
[[Image:disttubexch.jpg|right|thumb|300px|<small><center>Exchange in the Principal Cells of the Distal Tubule</center></small>]]
* Important site of regulation of ions and water
* Less emphasis on bulk transport compared with proximal tubule
* More emphasis on fine management
* It is able to do this as it has high resistance epithelia. Allowing it to maintain substantial gradients across it
* Very important for the homeostasis of:
** [[Sodium Homeostasis - Physiology#Distal Tubule and Collecting Ducts| Sodium]]
** [[Potassium Homeostasis - Physiology#Distal Tubule| Potassium]]
** [[Acid Base Balance By The Kidney - Anatomy & Physiology#Secretion of H+ in the Distal Tubule and Collecting Ducts| Acid Base]]
* There are two cell types present each with different functions. They are similar to the cells of the collecting ducts
** Principal cells
*** Absorb sodium
*** Excrete potassium and hydrogen
*** Site of action of [[Aldosterone]]
** Intercalated cells
*** ATP driven proton secretion
==Juxtaglomerular Apparatus==
[[Image:juxtaapp.jpg|right|thumb|200px|<small><center>Histology section showing the juxtaglomerular apparatus (© RVC 2008)</center></small>]]
* The terminal portion of the straight distal tubule contacts the afferent and efferent vessels supplying its own glomerulus
* These vessels are said to embrace the distal tubule
* Here a special apparatus called the Juxtaglomerular Apparatus has 3 different structures:
** The tubular epithelial cells of the distal tubule which are in contact with the arterioles supplying the glomerulus of that nephron are called the '''macula densa'''. They play a vital role in the [[Autoregulation of GFR - Anatomy and Physiology#Tubuloglomerular Feedback (TGF)|regulation of the GFR]].
** The [[Juxtaglomerular Cells of The Distal Tubule - Renal Physiology | Juxtaglomerular Cells]] are smooth muscle cells which adjoin the macula densa in the capillary wall.
** The Extraglomerular Mesangium has an unclear function
==Developmental==
Develops from metanephric tubule