Osmoregulation and Nitrogenous Waste

by Jason Amores Sumpter
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Hi In this lesson will be talking about the excretory system and Osma regulation. Osma regulation is thehyperfix static mechanism that allows organisms to balance their solute concentration and deal with water loss. Now excretion is the process of eliminating waste from the body and will absolutely involve loss of salutes and water from the body, which is why Theo Excretory System is heavily involved with Osma regulation. But the excretory system has another important job, and that's getting rid of nitrogenous waste, which we'll talk about in just a moment Now. The excretory system is made up of a few components. The main part is the kidney. That's like the business end of the excretory system. That's, uh, this being shaped Oregon. You actually have to one on either side of your body, and it's going to filter blood plasma and form urine. But it's a job is so much more sophisticated than that will really get into the details in just a moment. Now the kidney is going thio. Are the kidneys going? Thio uh, give off hearing that will be transported to the bladder by the Your Attar's thes are going to be tubes. Basically that lead from the kidneys to the bladder, which is the storage organ for urine and you're in will be stored there until it is ready to be eliminated through the urethra, which is the opening to the environment. Now, here you can see an example of a fish trying to maintain its osmotic balance, you know, by drinking seawater and, you know, passing water and salutes in and out of its body and excreting salutes so that it can maintain and Oz osmotic balance in its body. Now, nitrogenous waste is bad because ammonia is super top toxic substance. And it's on Lee safe in the animal body. If it's heavily diluted. Uh, it's gonna form from the breakdown of proteins. Nucleic assets, right. They both have nitrogen in their structures. And those nitrogen, they're gonna be given off as ammonia. This is for some organisms, okay? Because they can just heavily dilute the ammonia and eliminate it that way. Here, you can actually see what ammonia looks like. It's just a nitrogen with some hydrogen attached to it. And, uh, you know, organisms that have plenty of water around them, for example, like tadpoles, they'll, you know, often eliminate there nitrogenous waste of pneumonia because water is very plentiful for them. So it z okay for them to waste a lot of water, diluting the ammonia because there's plenty more available for organisms that have less water available. Yuria tends to be a better choice in terms of eliminating nitrogenous waste. Now it consumes energy. To make Yuria, those organisms have to take their ammonia and convert it into Yuria. And as you can see, ammonia is one nitrogen. Yuria has to nitrogen ins and a carbon and oxygen. It's actually basically formed by combining ammonia and Co. Two, that Z sort of oversimplified version of how area is made. The difference is it's way less toxic than pneumonia. And it is, uh, it doesn't need to be as heavily diluted. It could be excreted with minimal water loss, which is super important for, for example, terrestrial animals like us. We excrete area because we don't have that endless supply of water, you know, like all around us, like a tadpole, for example, so we don't wanna waste is much water getting rid of our nitrogenous waste. Some organisms, like organisms that live in really dry climates like reptiles in a desert, for example, will actually go even further and choose to excrete there nitrogenous waste as uric acid. You can see the uric acid right here. Jump out of the way so my head's not blocking it. And as you can see, ammonia had one nitrogen. Yuri had to nitrogen and uric acid has four nitrogen, so it is a bigger molecule, but it gets rid of more nitrogen. It costs more energy to produce than area. It's Mawr energy intensive. However, it's basically insoluble, so it can be excreted with almost no water loss, which is why it would be the appropriate choice for a desert dwelling organism like a lizard, for example, where water is extremely scarce. Now, the basic point I'm trying to make is that the type of waste excreted by an organism is tied to things like its evolutionary history and its habitat and its level of osmotic stress. So, uh, you know, for example, um, some birds excrete, you know, most of their nitrogenous waste as uric acid. But ducks, for example, excrete some like almost half really is Yuria, and the rest is uric acid because, you know they live in water the water fowl. They have mawr water available to them. So it's not, you know, specie necessarily species specific. It really depends on a variety of factors, including habitat. Now the other point I'm trying to make is that there's a fitness trade off between how much energy it costs. Thio produce the particular molecule that will get rid of this nitrogenous waste and conserving water. Right? You know, you might be able to save a lot of water by making uric acid, but it might cost you more energy than you can afford to produce it. So perhaps Yuria, for example, would be the better choice for you. You know, thes air, just sort of the trade offs of using either strategy. Point is, nothing's perfect in biology. It's just about doing the best you can give in your conditions. So with that, let's flip the page