 And this video is going to look at the many ways that your body tries to deal with dehydration or insufficient water in the body. You see at the top here. Let's start down the left hand side. You're going to see a decrease in blood volume. Whether you're losing water because you're urinating, you're sweating it, you're exhaling it in the air, it's ultimately coming from blood plasma because if you pull water from other places, there's going to be fluid shifts. This is how dehydration and sweating can remove blood plasma, which will decrease blood volume. So just remember that. In the end, any fluid leaving your body is being taken from your blood plasma. So a decrease in blood volume is going to lead to a decrease in blood pressure. So as blood volume goes up, pressure goes up, as blood volume goes down, blood pressure goes down. So we see a drop in blood pressure. Now, your body can't stand that, especially your kidneys. Your kidneys have sensors that whenever they sense a drop in blood pressure or blood volume in a drop in blood flow, then they're going to freak out. They're going to trigger the renin angiotensin aldosterone system, which has been covered in a separate video, which will lead to this angiotensin 2 being increased. It's going to lead to EPO or erythropoietin being produced. You make more blood cells. So the drop in blood volume and the drop in blood pressure is really going to scare your kidneys, but you also have baroreceptors like around your aorta and your neck that are going to notice this drop in blood pressure too. So your body isn't only going to respond by this by making you thirsty. It's also going to, using sympathetic nervous system, it's going to tell your heart to beat stronger, be faster, et cetera. So you're going to see your body is going to try to maintain homeostasis by increasing blood volume and blood pressure any way that it can. And we'll look at them any way that it does that there. But remember, angiotensin 2, very important. Go back and watch the renin angiotensin aldosterone system video, super, super important. Angiotensin 2 is also, I guess, the enzyme that makes it is a target for many of our antihypertensive medications, their ACE or angiotensin converting enzyme inhibitors. So that's kind of down the left-hand side, but these both sides are related because one of the things that angiotensin 2 does is makes you thirsty. All right. Now, on the other side, you see the increased blood osmolality. That means that you're going to have too much, too much solute in your blood for the amount of water or solvent that's there. And that, so you see right in the middle, the osmoreceptors, these are special receptors in the hypothalamus that if they sense that your blood is getting too concentrated, too much solute, then it will make you thirsty and trigger all these other things. It will also lead to a release in ADH, anti-diuretic hormone, which we've covered earlier. Anti-diuretic hormone opens more water channels in the urinary system, at the end of the nephron and the collecting ducts, to reabsorb more water to decrease urine production. That's going to be its key function, but it will also make you thirsty. So we're getting there. See how they're all related. And then if your blood is getting increased in osmolality, meaning there's too much solute for the amount of solvent or water that's around, you also get a dry mouth. This is actually primarily triggered by your sympathetic nervous system. So you always make saliva, but under sympathetic stimulation, you stop making the really watery, serious saliva and start making a thicker, stickier saliva. So the dry mouth is going to hopefully tell you that you're thirsty and that you should be drinking. But all these things are going to converge. Excuse me. I got it here. So we talked about the saliva changing. We talked about the thirst mechanism from the hypothalamus being kicked in. We talked about the renin angiotensin system. But in the end, you see you have the thirst centers and the hypothalamus being stimulated. Hopefully, you're going to drink more, and that's going to decrease the blood osmolality. You'll no longer be thirsty because you now have enough water. How much water you need to drink to not get thirsty or not have these problems, that depends on your water losses. I've already covered that in a separate video. So I think those are all going to be the key things there. I guess one more thing I will say, though, we thought we said it was the renin angiotensin aldosterone system. So I haven't mentioned aldosterone. Antidiuretic hormone opens water channels directly. Aldosterone is going to pump back sodium. It's going to increase the reabsorption of sodium. And then because of osmosis, sodium will follow it in. So the two work together. ADH and aldosterone are both going to decrease urine production, increase blood plasma, increase blood volume. OK, those are all the key things here. When does this system not work well? Very important to note that the infants and the elderly are at much higher risk for dehydration than other people. These systems just don't work like they should. So very, very important. Everyone stays hydrated. But make sure you keep the youngest of the young and the oldest of the old are definitely at the highest risk here. OK, that is how our body tries to maintain the appropriate amount of body water. I hope this helps. Have a wonderful day. Be blessed.