Juxtaglomerular apparatus

from Wikipedia, the free encyclopedia
Scheme of a kidney corpuscle and structures adjacent to it. A: kidney corpuscles , B: main piece , C: middle piece , D: juxtaglomerular apparatus . 5a. intraglomerular mesangial cells, 5b extraglomerular mesangial cells, 6. juxtaglomerular cells (polar cushion), 7. macula densa

The juxtaglomerular apparatus (from Latin juxta : "near" and glomerulum ) is in the nephron , the functional unit of the kidney , the contact point between the supplying blood vessel ( vas afferens ) and the distal renal tubule. Here, among other things, the enzyme renin , which is important for regulating the electrolyte and water balance and blood pressure, is formed, which is then transported to the liver via the blood vessel system (→ Renin-Angiotensin-Aldosterone System / RAAS ).

construction

The juxtaglomerular apparatus is made up of three parts:

  • The macula densa is a chemosensitive field consisting of tall, densely packed epithelial cells in the wall of the straight distal tubule of the renal tubule that belongs to this glomerulus.
  • The renin- containing ( granulated ) epithelioid myocytes (i.e. muscle cells located in the epithelium), known as pole pillows , which also appear under the term juxtaglomerular cells , in the wall of the vas afferens.
  • Extraglomerular mesangial cells or Goormaghtigh cells are found enclosed by the vas afferens , vas efferens and the macula densa .

The polar cushions form the vascular enzyme renin, which plays an important role in the RAAS.

Diseases

In the case of a tumor (reninoma), e.g. B. Hemangiopericytoma , nephroblastoma , there may be an increased production of renin ( hyperreninism ).

Individual evidence

  1. ^ Pschyrembel online

Web links