Product Code Database
Example Keywords: nokia -scarf $68-193
   » » Wiki: Distal Convoluted Tubule
Tag Wiki 'Distal Convoluted Tubule'.
Tag
20%

The distal convoluted tubule ( DCT) is a portion of between the loop of Henle and the collecting tubule.


Physiology
It is partly responsible for the regulation of , , , and pH.

On its surface (lumen side), cells of the DCT have a thiazide-sensitive Na-Cl cotransporter and are permeable to Ca, via the TRPV5 channel. On the surface (peritubular capillary side) there is an ATP-dependent Na/K pump, a secondary active Na/Ca transporter, and an Ca transporter. The basolateral ATP dependent Na/K pump produces the gradient for Na to be absorbed from the apical surface via the Na/Cl , and for Ca to be reclaimed into the blood by the Na/Ca basolateral antiporter.

  • It regulates pH by absorbing and secreting (H+) into the filtrate, or by absorbing and secreting into the filtrate.
  • Sodium and potassium levels are controlled by secreting K+ and absorbing Na+. Sodium absorption by the distal tubule is mediated by the . Aldosterone increases sodium reabsorption. Sodium and chloride (salt) reabsorption is also mediated by a group of kinases called WNK kinases. There are 4 different WNK kinases, , , , and .
  • It also participates in regulation by reabsorbing Ca2+ in response to parathyroid hormone. PTH effect is mediated through phosphorylation of regulatory proteins and enhancing the synthesis of all transporters within the distal convoluted tubule.
  • Arginine vasopressin receptor 2 is also expressed in the DCT.


Clinical significance
inhibit Na+/Cl reabsorption from the DCT by blocking the thiazide-sensitive Na-Cl cotransporter.

By inhibiting the transporter, thiazide diuretics increase the gradient potential for Na. This increases the activity of the basolateral Na/Ca antiport and causes the increase in calcium reclamation associated with thiazide diuretics.


Histology
The DCT is lined with simple cuboidal cells, the distal convoluted tubule cells, that are shorter than those of the proximal convoluted tubule (PCT). The lumen appears larger in the PCT than the DCT lumen because the PCT has a brush border (microvilli). DCT can be recognized by its numerous (even though it is not as much as PCT), basal enfoldings and lateral membrane interdigitations with neighboring cells.

The point where DCT contacts the thick ascending limb of the loop of Henle is called . It has tightly packed columnar cells which display reversed polarity and may monitor the osmolarity of blood.

, cells of the DCT can be differentiated from cells of the proximal convoluted tubule:

Not present
Less
Less
More likely

==Additional images==


See also
List of distinct cell types in the adult human body


External links
Page 1 of 1
1
Post Comment
Font Size...
Font Family...
Font Format...

Page 1 of 1
1

Account

Social:
Pages:  ..   .. 
Items:  .. 

Navigation

General: Atom Feed Atom Feed  .. 
Help:  ..   .. 
Category:  ..   .. 
Media:  ..   .. 
Posts:  ..   ..   .. 

Statistics

Page:  .. 
Summary:  .. 
1 Tags
10/10 Page Rank
5 Page Refs