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The RAAS system

Hi all

I've just been revising the RAAS system in kidneys and I was just wondering what activates it? Would it be dehydration (I thought ADH levels were increased to counter act this) or changes in salt balance in the body? Eg drinking saline solution?

Also what are they effects on the filtration system when drinking saline?

Reply 1

thegodofgod

Original post by ThrashMetal

It can be activated by loss of blood volume or hypotension, e.g. dehydration or haemorrhage, which is detected by baroreceptors in the carotid sinus. Otherwise, a decreased concentration of Na⁺ or Cl^- in glomerular filtrate would be detected by the macula densa cells, which would signal to the juxtaglomerular cells to release renin.

I suppose you could think of the ADH mechanism as an additional mechanism to the RAAS in order to ensure that plasma volume becomes normal more quickly.

Hope this helps!