 Well the next topic is Osmo regulation in vertebrates. Osmo regulation means that Kistra vertebrates, they maintain water balance. This is what is called as the Osmo regulation. So there's a variety of mechanisms which have been evolved in vertebrates to cope with the Osmo regulatory problems and most of them are adaptations of the urinary system. Because urinary system is the system which has maximum water loss. And due to this, this nitrogen waste is also removed. So this is very important to maintain the Osmo regulation. If the water retain, then urine will pass less. If the water loses more, then this is something which is automatic. It is under the control of nerves or under the control of the hormones. So the vertebrates have a closed circulatory system containing blood that is under pressure. Or under pressure you have, you can say, that is by the throbbing of the heart or by muscular contraction. Now this pressure, there is blood forces to pass through the membranes or membrane kaha hai, that is usually that is in the in the in the kidneys or we can say that is in the part of the excretory system. We are the following three functions which are very important functions which we will read in detail. And here is a simple name or explanation of it. That is filtration, then reabsorption or secretion. And these are the three main processes which are in the kidneys. The first is filtration. The filtration is like the name shows that blood is filtered and then the filtrate is made. And on the filter, as we call it as residue, they are usually the red blood cells, the white blood cells or bigger cells. So in this process blood passes through a filter that retains blood cells, proteins and other large solutes. But let small molecules that is ions and urea that is passed through. So this is the function of the filter. If we have to filter something from a filter paper, then of course something, the small things which pass through the filter paper and when those things come in the residue, which cannot pass through, which are usually bigger molecules. Then next process is reabsorption. Reabsorption, that means that the reabsorption, there is a selective reabsorption. Select molecules, they come back again into the bloodstream. And this means that they can maintain the solute concentration. And taken back into the bloodstream from the filtrate, then the other important things are absorbed again into the bloodstream. And lastly the secretion, this is a process, it may be select molecules and end products of metabolism, which are usually potassium, hydrogen or ammonia. They are reabsorbed, they are in the blood and added to the filtrate for removal from the body. And this is also a selection, which are to be retained within the blood and which are to be absorbed into the coming out urine. Or this urine that comes out of the body containing the excessive water as well as containing the excessive solutes, which are surplus. So these are three very important steps. First the blood is filtered, then the reabsorption occurs and lastly the secretion. So this is all about this small topic. So this is all that.