Biology Forums - Study Force

In case of loss of blood the blood pressure decrease so the RAAS will be activated, and these hormones (mostly the aldosterone) increase the blood pressure in the entire body.
My question is that how do these hormones increase the blood volume and the blood pressure in the entire body, if their target cells are mostly jut the kidney tubule's cells?
I hope somebody can explain me the whole mechanism of the RAAS action.

alright so you have the basics down. The renin system like you said is when there is a massive loss in blood pressure. So if you have a massive hemorrhage for example. It is not used for everyday fluctuations in BP  because the system is way to strong

1. lose a lot of blood so BP drops way down
2. the kidneys sense tis loss of pressure at the juxta and releases renin
3. this causes the liver to release angiotensinogen which is then converted into angiotensin 1. It then goes to the lungs to pick up a substance called ACE which converts it to angiotensin 2.
4. from there angiotensin 2 does 3 things to increase BP
   1. it increases sympathetic activity, so the fight or flight response which causes vasoconstriction and an increase in HR
   2. causes the release of aldosterone from the kidneys which retains all ions like Salt, water follows salt, which increases blood volume = increase in BP
   3. Causes the release ADH- this an antidiuretic hormone which causes you to retain water

so to answer your question yes angiotensin targets the kidney but then the kid releases 3 hormones that affect systemic blood pressure. hope this makes more sense ! kind of a confusing system but very effective.

Thank you!