Distal convoluted tubule

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Distal convoluted tubule
Kidney nephron (labeled as "2nd convoluted tubule", near top)
Section of cortex of human kidney.
Latin tubulus contortus distalis
Gray's subject #253 1223
Precursor Metanephric blastema
MeSH Distal+Kidney+Tubule
Dorlands/Elsevier t_22/12830066

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

Contents

It is partly responsible for the regulation of potassium, sodium, calcium, and pH.

  • Sodium and potassium levels are controlled by secreting K+ and absorbing Na+. 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, WNK1, WNK2, WNK3, and WNK4.

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

The distal convoluted tubule (DCT)is the final segment of the nephron. It is lined with simple cuboidal cells that are shorter then 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.

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

Characteristic PCT DCT
apical brush border? usually have do not have
eosinophilicity? more less
cytoplasm? more less
have visible nuclei? less likely more likely

1 Glomerulus, 2 proximal tubule, 3 distal tubule

Transverse section of pyramidal substance of kidney of pig, the bloodvessels of which are injected.

  1. ^ MedEd at Loyola mech/cases/case24/kidney.htm

v • d • e
Urinary system - Kidney
Layers Renal fascia • Renal capsule • Renal cortex  (Renal column) • Renal medulla (Renal sinus, Renal pyramids) • Renal lobe • Cortical lobule • Medullary ray • Nephron
Afferent circulation Renal artery → Segmental arteries → Interlobar arteries → Arcuate arteries → Cortical radial arteries → Afferent arterioles → Renal corpuscle (Glomerulus, Bowman's capsule)
Renal tubule Proximal tubule → Loop of Henle (Descending, Thin ascending, Thick ascending) → Distal convoluted tubule → Connecting tubule → Collecting ducts → Duct of Bellini → Renal papilla → Minor calyx → Major calyx → Renal pelvis → Ureter
Efferent circulation Glomerulus → Efferent arterioles → Peritubular capillaries/Vasa recta → Arcuate vein → Interlobar veins → Renal vein
Juxtaglomerular apparatus Macula densa • Juxtaglomerular cells • Extraglomerular mesangial cell
Filtration Glomerular basement membrane • Podocyte • Filtration slits • Intraglomerular mesangial cell • Tubular fluid
Renal physiology Acid base physiology • Fluid balance


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