Juxtaglomerular apparatus
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
Web links
- Juxtaglomerular apparatus ( memento from March 29, 2013 in the Internet Archive ) on the website of the Sports Medicine Faculty of the Ruhr University Bochum