let's review the ran in Angiotensin aldosterone system also known as Ras okay so let's say you have a patient who has fluid volume deficit so thinking back to our lecture on fluid volume deficit we know that our patient has low fluid in their body and this can cause a low blood pressure and our body doesn't like a low blood pressure so whenever it senses this this rash system is going to kick in and the whole goal of the system is to increase your blood pressure and how it does this is it gets Angiotensin II involved which is a hormone that's also going to stimulate other hormones such as aldosterone and ADH that anti-diuretic hormone and those hormones are going to add more water to your blood to help increase blood volume hence increase blood pressure so how this system works is that your blood pressure drops that drop in blood pressure indicates to the body hey we have a loss of fluid so we've got to do something about this and this causes the kidneys to respond specifically the juxta glomerular cells inside that kidney and they are going to release a substance called renin and whenever renin is present in the blood circulation this causes the liver to respond and whenever the liver responds it is going to activate a substance called angiotensinogen and whenever angiotensinogen is there it actually turns into a substance called Angiotensin one so we have Angiotensin one but again the whole goal is to get Angiotensin II involved because that is that big major hormone that's going to actually cause some things to happen so we've got to get there now how do we get there from Angiotensin 1 to Angiotensin II well that is where Ace comes in a stands for Angiotensin converting enzyme and this helps turn Angiotensin 1 into Angiotensin II and now that we have Angiotensin II involved things are going to start getting interesting because now we'll be able to achieve our goal of increasing that blood pressure because Angiotensin II has major effects on the body one thing it does is it causes vasoconstriction so we're going to get narrowing of those vessels and when we narrow those vessels it's actually going to constrict the blood flow to the kidneys and limit its ability to excrete water which is what we want because we want that water to stay in the body right now so we can increase our blood volume hence increase our blood pressure in addition Angiotensin 2 is going to cause our adrenal cortex to release a hormone called aldosterone and aldosterone will cause the kidneys to keep sodium which will also cause us to keep water and again we want to do this because we're trying to increase our blood volume so whenever this happens your patient will have a temporary decrease in their urination which again is what we want and then another thing Angiotensin II does is it causes the posterior pituitary gland to release a hormone called ADH which again is anti-diuretic hormone so how this works is it's going to cause the kidneys to keep water and whenever we keep water we're going to increase blood volume so think of it this way if you're familiar with how diuretics work we get patients diuretics to help them urinate extra fluid out of the body it's used to treat a lot of times fluid volume overload well if we're having a substance in our body called antidiuretic anti-means works against we're working against that concept so let that help you remember what ADH does ADH is going to cause your body to keep water it has an antidiuretic effect and then lastly another thing Angiotensin II does is it stimulates the thirst mechanism if you like to watch more videos in this fluid electrolyte series you can access the link in the YouTube description below