The RAAS is activated whenever blood flow through the kidneys is reduced and when there are sodium losses in conditions such as diarrhoes, vomiting or excessive sweating. These losses reduce extracellular fluid volume and this in turn reduces arterial blood pressure, which triggers the RAAS system through several different mechanisms. | The RAAS is activated whenever blood flow through the kidneys is reduced and when there are sodium losses in conditions such as diarrhoes, vomiting or excessive sweating. These losses reduce extracellular fluid volume and this in turn reduces arterial blood pressure, which triggers the RAAS system through several different mechanisms. |