Question 3. The length of the loop of Henle is different in diflerent species. Why might its length be an adaptation that helps animals to survive in hotter or drie...

Which of these is not an adaptation that helps kangaroo rats conserve water?
a. formation of a very hypertonic urine
b. highly convoluted nasal passages
c. production of very dry feces
d. relatively long loops of the nephron in kidneys
e. secretion of excess salt from glands near eyes

All right. So for problem number 11 we're looking at the loop of Henle e um, specifically in mammals. And we're seeing why it produces concentrated urine or what the process is behind that. That's gonna help us answer this question. So creating concentrated urine and a mammal means that the animal is dehydrated. So we'll right that here, the top concentrated you're in equals dehydration. So this is like if our pee is yellow, it means we're dehydrated because but because here in the middle, because the animal is trying, you re absorb h too low or water, the animals trying to re absorb that water because it's dehydrated and that leads left over concentrated urine. So move down here. Let's figure out why mammals couldn't do this if they lacked a loop of Henley. Remember, the loop of Henle E is this simple structure comes down. Looks like a loop, okay? And never it is a hoob. You'll actually gets bigger up year. All right. To remember what mammals do is they re absorb water on the way down this loop. So as fluids removing down this loop, the animal is re absorbing water three absorbing H to Uh, and inside this loop is also all these Saul used heavily. I, aunt. And so as we start going up through this, too, we start re absorbing electrolytes, even all the way up here. So three absorbing and we'll just call them Saul. You. But they are also electrolytes because they are charged. So we're also re absorbing follies. So basically, the loop of Henle e you Lou of suddenly allows mammals to regulate h 20 and saw you and show, so that should lead. Lead us to. Our overall answer is that if mammals don't have a loop of Henley, then they can't do all of this stuff here. They wouldn't be able to re absorb water. They wouldn't be able to re absorb Salyut, and so they wouldn't be able to create concentrated urine because that's when mawr water is taken out. The normal

All right. So here I have drawn a picture of a Neff Ron, or at least part of an Effron. And the yellow part here represents an Effron in the Net. Farrand. The main part of it is split into these three sections. We have the proximal convoluted tubules. This loop right here is called the loop of Henle E and then the distal convoluted tubules. And so your fill trait that that's moving through your body is coming in this way and your kidneys. And so this questions asking specifically about the loop of Henle e on why it's important in producing concentrated urine. And so when fluid is moving through this proximal convoluted tubules, it will exchange saw Eudes like salt, potassium and if they need to be re absorbed, depending on the concentration in your blood will be re absorbed right here in the blood vessels. And so I've drawn really simply this red line representing blood vessels. And as it moves through the Nef Ron, it'll move this way. And when it reaches the loop of Henle E, what the loop of Henle E does is it's in control of the re absorption of water and So if water stays in the yellow part in the nef Ron, it'll eventually exit out and become urine. But if you're dehydrated, then your body will tell. Um tell itself to Teoh re absorb water from there. And so I've only drawn 11 red line here. But really there's a network of blood vessels all around this entire thing and specifically the network of blood vessels and specifically the type of blood vessel is there. Capital Aires. This section right here is called the vase director. And so what it does is it can re absorb water from the loop of Hindley so that you make sure you have the right amount of water bounds. Now, if you have too much water, then water can be secreted into the loop of Henle E from the blood vessels. And so what? The loop of Henle E and the vase director do is they work to balance the amount of water in your body and therefore they form and our response before creating urine that exits out of your body and gets rid of unneeded water and unneeded waste. So that's how they're involved in your input in the formation of concentrated urine

All right. So, for this question we are um proposed hypothetical. So here we have mammals of the same size. So we're controlling for things such as metabolism and amount of food, all these sort of things. And we need to think about for mammals of the same size? What excretory feature? So what factor or part of the excretory system would give them the greatest ability to produce hyper tonic urine. So what would allow them to produce hyper tonic urine? And first of all, we need to understand what hyper tonic urine is. If we don't already, then it's hard to uh conceptually tackle this problem. So hyper tonic just means more waste and salutes in the urine. So more nitrogen, it's gonna be more concentrated. We're thinking about your in uh if it's going to be more water. So hippo tonic would have that uh clear urine. But this was a human instance. We think about that yellow you're in that has the ammonia, sort of or not ammonia. Somewhere we excrete, but that just say unfavorable odor potentially trying to get too graphic. I'm just trying to conceptually explain this. So what would allow this more concentrated urine to exist? We're we're conserving more water and getting rid of more salts and waste. So we need to think about the portion of the kidney that's responsible for things such as urine production rates and globular filtration. And uh we need to think about essentially the loop of Henley because in loop of Henley, we're going to have the concentration gradients, right? We have to concentration gradients of the water that you're trying to conserve and then self going back towards the source. We're gonna have the water because we want to keep if we don't have enough water in our body, want to keep as much water. So the larger the concentration gradients than more water that can be conserved, right? And then the nitrogenous wastes or the wastes in general, which we want the bigger concentration gradients because we want to get rid of those as much as possible. So what will maximize these concentration gradients? Mckee is the loop of henley because the longer it is, the bigger the concentration gradient will be and the more concentrated the urine will be because more waste. We're getting rid of the more water we're going to conserve. So the key to this is going to be longer loops of henley, which is going to be answer option E be longer groups of Henley.

When we have same size mammals, what would enable them to have the best ability to concentrate the urine with regards to the excretory system? So for same sized mammals to have the best ability to concentrate their urine, they would need to have longer loops of henley, and the loops of henley, for our knowledge, has to do with the net print of the kidney.