Distal convoluted tubule 490690 206698252 2008-04-19T14:53:23Z Kuebi 3115875 /* Histology */ cosmetics {{Infobox Anatomy | Name = Distal convoluted tubule | Latin = tubulus contortus distalis | GraySubject = 253 | GrayPage = 1223 | Image = Kidney_nephron.png | Caption = Kidney nephron (labeled as "2nd convoluted tubule", near top) | Image2 = Gray1132.png | Caption2 = Section of cortex of human kidney. | Precursor = [[Metanephric blastema]] | System = | Artery = | Vein = | Nerve = | Lymph = | MeshName = Distal+Kidney+Tubule | MeshNumber = | DorlandsPre = t_22 | DorlandsSuf = 12830066 | }} The '''distal convoluted tubule''' ('''DCT''') is a portion of [[kidney]] [[nephron]] between the [[loop of Henle]] and the [[collecting duct system]]. == Physiology == It is partly responsible for the regulation of [[potassium]], [[sodium]], [[calcium]], and [[pH]]. * It regulates pH by absorbing [[bicarbonate]] and secreting [[proton]]s (H<sup>+</sup>) into the filtrate. * Sodium and potassium levels are controlled by secreting K<sup>+</sup> and absorbing Na<sup>+</sup>. Sodium absorption by the distal tubule is mediated by the [[hormone]] [[aldosterone]]. Aldosterone increases sodium reabsorption. Sodium and chlorine (salt) reabsorption is also mediated by a group of kinases called WNK kinases. There are 4 different WNK kinases, {{Gene|WNK1}}, {{Gene|WNK2}}, {{Gene|WNK3}}, and {{Gene|WNK4}}. * It also participates in [[calcium]] regulation by absorbing Ca<sup>2+</sup> in response to [[parathyroid hormone]].<ref>{{LoyolaMedEd|mech/cases/case24/kidney.htm}}</ref> * [[Arginine vasopressin receptor 2]] is also expressed in the DCT. ==Clinical significance== [[Thiazide]] [[diuretic]]s inhibit Na<sup>+</sup>/Cl<sup>-</sup> reabsorption from the DCT by blocking the [[thiazide-sensitive Na-Cl cotransporter]]. == Histology == <!--Kidney distal tubule cell redirects here--> The distal convoluted tubule (DCT) is the final segment of the nephron. It is lined with simple cuboidal cells that are shorter than those of the PCT. The lumen appears larger in DCT than the [[proximal convoluted tubule]] (PCT) lumen because the PCT has a brush border (microvilli). DCT can be recognized by its numerous [[mitochondria]], basal infoldings and lateral membrane interdigitations with neighboring cells. The point where DCT contacts afferent arteriole of renal corpuscle is called [[macula densa]]. It has tightly packed columnar cells which display reversed polarity and may monitor the osmolarity of blood. [[Histology|Histologically]], cells of the DCT can be differentiated from cells of the [[proximal convoluted tubule]]: {| class="wikitable" | '''Characteristic''' || '''PCT''' || '''DCT''' |- | [[apical]] [[brush border]]? || usually have || do not have |- | [[eosinophil]]icity? || more || less |- | [[cytoplasm]]? || more || less |- | have visible [[cell nucleus|nuclei]]? || less likely || more likely |} ==Additional images== <gallery> Image:Histology-kidney.jpg |1 [[Glomerulus]], 2 [[Proximal convoluted tubule|proximal tubule]], 3 distal tubule Image:Gray1133.png|Transverse section of pyramidal substance of kidney of pig, the bloodvessels of which are injected. </gallery> ==References== <references/> == External links == * {{UCDavisOrganology|Urinary/mammal/cortex1/cortex7}} - "Mammal, kidney cortex (LM, Medium)" * {{OklahomaHistology|35_19}} * {{GeorgiaPhysiology|7/7ch03/7ch03p18}} * {{GeorgiaPhysiology|7/7ch07/7ch07p14}} * {{BUHistology|16004loa}} * {{BUHistology|16007loa}} {{kidney}} [[Category:Kidney]] {{anatomy-stub}} [[es:Túbulo contorneado distal]] [[ja:遠位尿細管]]