Quelltext der Seite Renin-Angiotensin-Aldosteron-System (RAAS)/en

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Important medium-term regulatory system of blood pressure via [[salt, electrolyte/salt]]<nowiki />household and [[plasma]]<nowiki />volume based on [[renin]]<nowiki />release and [[angiotensin II]] formation. 

The '''Renin-Angiotensin-Aldosterone System'' regulates the fluid and electrolyte balance and thus has a decisive effect on arterial blood pressure. All players of the renin-angiotensin-aldosterone system interact closely with each other. A series of enzymatic reactions leads to the physiologically highly effective [https://flexikon.doccheck.com/de/Angiotensin_II Angiotensin II].

At the beginning of the RAAS stands Renin. It is a protease produced mainly in the juxtaglomerular apparatus and there in the epitheloid cells of the vas afferentia. Renin cleaves the peptide angiotensionogen formed in the liver into angiotensin I. This is then converted into highly active angiotensin II by the conversion enzyme (angiotensin converting enzyme; ACE, formed in the pulmonary tract).

Above all, angiotensin II has a strong [https://flexikon.doccheck.com/de/Vasokonstriktion vasoconstrictor] effect - this occurs via the central activation of the sympathetic nervous system. The result is an increase in [https://flexikon.doccheck.com/de/Blutdruck blood pressure] and thus an increased blood flow to all [https://flexikon.doccheck.com/de/Organ organs] (including the glomeruli, from which the original stimulus originated).

[[File:RAAS.png]]

Source: Wikipedia / D. Varga / [http://creativecommons.org/licenses/by-sa/3.0/ CC BY-SA 3.0]

Angiotensin II also has the following effects:

It causes an increased [https://flexikon.doccheck.com/de/Aldosteron aldosterone release] from the [https://flexikon.doccheck.com/de/Nebennierenrinde adrenal cortex] and this in turn causes an increased [https://flexikon.doccheck.com/de/R%C3%BCckresorption reabsorption] of [https://flexikon.doccheck.com/de/Natrium sodium] and [https://flexikon.doccheck.com/de/Chlorid chloride ions] and an increased excretion of [https://flexikon.doccheck.com/de/Kalium potassium ions] in the [https://flexikon.doccheck.com/de/Nierentubulus renal tubules]. For [https://flexikon.doccheck.com/de/Osmose osmotic] reasons, more water is also reabsorbed, which leads to an increase in the volume of [https://flexikon.doccheck.com/de/Blut blood] and thus additionally increases blood pressure. 

It also causes an increased release of the [https://flexikon.doccheck.com/de/Antidiuretisches_Hormone antidiuretic hormone] (ADH) from the [https://flexikon.doccheck.com/de/Hypophyse_Hypophyseal posterior lobe], resulting in increased reabsorption of water into the renal tubules and vasoconstriction. These effects also increase blood pressure.

Angiotensin II steigert auch die Durstempfindung

https://de.wikipedia.org/wiki/Renin-Angiotensin-Aldosteron-System <sub>([https://de.wikipedia.org/wiki/Wikipedia:Lizenzbestimmungen_Commons_Attribution-ShareAlike_3.0_Unported Wikipedia CC-by-sa-3.0])</sub>