Difference between revisions of "Reabsorption and Secretion Along the Distal Tubule and Collecting Duct - Anatomy & Physiology"

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==Distal Tubule==
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[[Image:disttubexch.jpg|right|thumb|300px|<small><center>Exchange in the Principal Cells of the Distal Tubule</center></small>]]
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* Important site of regulation of ions and water
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* Less emphasis on bulk transport compared with proximal tubule
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* More emphasis on fine management
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* It is able to do this as it has high resistance epithelia.  Allowing it to maintain substantial gradients across it
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* Very important for the homeostasis of:
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** [[Sodium Homeostasis - Physiology#Distal Tubule and Collecting Ducts| Sodium]]
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** [[Potassium Homeostasis - Physiology#Distal Tubule| Potassium]]
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** [[Acid Base Balance By The Kidney - Anatomy & Physiology#Secretion of H+ in the Distal Tubule and Collecting Ducts| Acid Base]]
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* There are two cell types present each with different functions.  They are similar to the cells of the collecting ducts
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** Principal cells
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*** Absorb sodium
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*** Excrete potassium and hydrogen
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*** Site of action of [[Aldosterone]]
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** Intercalated cells
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*** ATP driven proton secretion
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==Juxtaglomerular Apparatus==
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[[Image:juxtaapp.jpg|right|thumb|200px|<small><center>Histology section showing the juxtaglomerular apparatus (© RVC 2008)</center></small>]]
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* The terminal portion of the straight distal tubule contacts the afferent and efferent vessels supplying its own glomerulus
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* These vessels are said to embrace the distal tubule
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* Here a special apparatus called the Juxtaglomerular Apparatus has 3 different structures:
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** 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]].
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** The [[Juxtaglomerular Cells of The Distal Tubule - Renal Physiology | Juxtaglomerular Cells]] are smooth muscle cells which adjoin the macula densa in the capillary wall.
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** The Extraglomerular Mesangium has an unclear function
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==Developmental==
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Develops from metanephric tubule

Revision as of 15:07, 3 September 2008

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()Map REABSORPTION AND SECRETION ALONG THE NEPHRON (Map)



Distal Tubule

Exchange in the Principal Cells of the Distal Tubule
  • 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:


  • 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

Histology section showing the juxtaglomerular apparatus (© RVC 2008)
  • 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 regulation of the GFR.
    • The 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

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