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Renal urea handling



Renal ura handling is the part of renal physiology that deals with the reabsorption and secretion of urea.

Additional recommended knowledge

Urea allows the body to create hyperosmotic urine (urine that has more ions in it--is "more concentrated"--than that same person's blood plasma). Preventing the loss of water in this manner is important if the person's body needs to save water in order to maintain a suitable blood pressure or (more likely,) in order to maintain a suitable concentration of sodium ions in the blood plasma.

About half of the urea filtered (40%[1]) is normally found in the final urine, since there is more reabsorption than secretion along the nephron.

It is regulated by antidiuretic hormone, which controls the amount reabsorbed in the collecting duct system and secreted into the loop of Henle.

Overview table

Characteristic proximal tubule loop of Henle Distal convoluted tubule Collecting duct system
S1 S2 S3 descending limb thin ascending limb thick ascending limb connecting tubule initial collecting tubule cortical collecting ducts medullary collecting ducts
reabsorption (% compared to filtered amount) 50[1] 70
secretion (% compared to filtered amount) 60[1]
reabsorption (mmoles/day)
Concentration
electrical driving force (mV) -3[2] +3[2] +15[2] -5 to +5[2] -40[2]
chemical driving force (mV)
electrochemical driving force (mV)
apical transport proteins
  • solvent drag[1]
  • unknwn transporter[1]
  • Urea transporter 2?[1]
  • unknwn transporter[1]
  • urea transporter 1[1]
basolateral transport proteins
  • unknown transporter[1]
  • Urea transporter 2?[1]
  • unknwn transporter[1]
  • urea transporter 4[1]
Other reabsorption features

References

  1. ^ a b c d e f g h i j k l Walter F., PhD. Boron. Medical Physiology: A Cellular And Molecular Approaoch. Elsevier/Saunders. ISBN 1-4160-2328-3.  Page 791
  2. ^ a b c d e Walter F., PhD. Boron. Medical Physiology: A Cellular And Molecular Approaoch. Elsevier/Saunders. ISBN 1-4160-2328-3.  Page 777
 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Renal_urea_handling". A list of authors is available in Wikipedia.
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