 Hey everybody, Dr. O here. In this video we're going to talk about the functions of the urinary system. So here we see urine. Why do we make urine? Why does urine look like it does? Why does it have what it has in it? So we'll cover a lot of that later when we look at the composition of urine. But the big picture here is that urine is basically filtered blood. That's the simplest way to look at it. So your body takes what's in the blood that it needs to get rid of and puts it in urine. Your body will also put the excess of things that it likes like glucose in urine if it can't keep all of it. And your body will also conserve nutrients by bringing things back in before urine leaves the body. So that's the simplest way to look at it is think about urine as filtered blood. We actually take, our kidneys are going to filter 50 gallons of fluid every day. And they conserve and reabsorb and take most of that back in. So what's left is you're one to two liters of this, this urine. But what are the actual functions of the system? So here we see the urinary system. And we'll go through all the structural pieces in the next video. But the three functions of the urinary system. Our number one is the excretion, the removal of organic waste products. Simple way to look at it is your metabolism is poisoning you every second of every day. You've got to get those materials out of your body. And one of the best ways to do that is through urine, which is why if your kidneys aren't functioning and you're not producing urine, you'll need dialysis, which basically functions like a kidney and removes these metabolic poisons from your blood. What are some of these metabolic poisons? The most abundant is urea, which is a byproduct of the breakdown of amino acids. You have creatinine, which is a byproduct of skeletal muscle contraction. And then you have uric acid, which is a byproduct of the recycling of RNA. So those are going to be like your three key organic metabolic waste products. So if you're not excreting them, getting them out of your blood, then you'd be poisoned by them. So that's function one, excretion. Function two is elimination. So now you've made this urine. We've got to get it out into the environment, obviously, into the toilet usually. So that'd be the elimination part. We'll talk about the ureters and the bladder and everything else in future videos. Then number three is we mentioned that urine is filtered blood. It's the homeostatic regulation of the concentration and composition of your blood. So by putting things you don't want in your blood in your urine, you're creating better blood. By reabsorbing things you want to keep and putting it back into your blood, you're creating better blood. Kind of one last thing on this point, though, is why do we have to make urine? Why do we actually urinate? If we have metabolic waste products, why can't we just pee dust? And I'm not trying to be crass there, but why don't we just pee dust? Because even if you're dehydrated, you're still going to need to make urine to get rid of these metabolic waste products. And that's because they're dissolved in the water. They're dissolved in fluid. They're water soluble. And the only way to carry them out of your body is with fluid. So that's why even if you're dehydrated, you will still make urine. It would be great if there was another way to get rid of these waste products, but there isn't. All right. Other things. So we talked about the excretion and metabolic waste products, getting them out of your body, out of your blood, into your urine, elimination of the urine, out of your body. And then we talked about its role in determining the amount and composition of the blood we have. And that's great. So we've talked about it basically cleansing the blood as far as a function. And we'll see that in the next chapter that it plays a really big role in regulating pH. So your kidneys and your lungs are the two major organs that help your body maintain acid-base balance. So the regulation of pH is something we'll talk about. Blood pressure. So by regulating blood volume, it'll regulate blood pressure, but also it can release hormones that stimulate blood pressure, increase blood pressure. Your kidneys play a role in how many red blood cells you have by releasing the hormone erythropoietin that we've already covered. It plays the final step in the conversion of making functional vitamin D happens in the kidneys. So as you can see, a whole lot of things are going on there, but we'll focus on those big ones. Okay. So those are the functions. That's why you have a urinary system. Next we'll look at the actual players, the pieces of the anatomy of your urinary system. Okay. I hope this helped. Have a wonderful day. Be blessed.