Aya-la-ji. So, now let's look at excretion in animals. So, how does excretion take place in animals? So, basically in animals you see that this is mainly carried out by a elaborate system made up of specialized tissues and organs and cells. So, in the animals, so excretion is mainly carried out by different specialized organ, different specialized cells, different specialized tissues. So, for animals, basically we see that most animals are higher organism. If we speak about higher organism, therefore we mean that this is not a unicellular organism. This is a multi-cellular organism. That is the reason why it is called a higher organism, because it comprises of very many cells brought together to form an organism, a whole organism. Therefore, a whole organism must use a complex excretory system in order to be able to eliminate all the waste products from the body. So, this is because most animals are made up of different organs which produce a lot of waste. They are made up of different tissues which also produce a lot of waste. So, since these organs and tissues, they produce a lot of waste. Therefore, they are needed to have a very much complex excretory system. The one that will remove this type of waste products, the one that will remove this type of waste products, etc. Therefore, for this organism, high organisms we see that, the diffusion alone cannot be able to remove all the waste products from their body. Because, the diffusion only deals with removal of very less toxic or removal of very low quantity of waste. But, for the higher organisms, they produce a lot of waste within a short period of time. Therefore, the diffusion alone cannot be able to serve as the main excretory agent to remove the waste products from the bodies of these different organisms that we have. Therefore, as we can look at these tables, so the table below summarise the different excretory organs by the animals. So, as you can look at this table, we have two columns. So, the first one is the column for the type of animal, then the second column is the column for... Now, the organ which is mainly used for the excretion of the different excretory products for the body. So, first of all, let us begin with the anelids. So, for the anelids are for... Yeah, the anelids, they mainly comprise of the round worms. So, the anelids, they mainly comprise of the worms. So, for the anelids, we see that they basically use nephriedia and organ which is called nephriedia for removal of waste products from their bodies. So, that is for the anelids. So, they basically use nephriedia for the removal of waste products from their body. So, in classification, we are going to expound more on nephriedia. So, how does nephriedia look like? So, what are the functions of nephriedia? So, in classification, we are going to expound more on nephriedia and we are going to study on nephriedia to see how it functions in order to remove the waste products from the bodies of the worms. So, apart from that, the next one we have the insects, the different insects that we have. So, for the organ of excretion for insects, we have the malpigian tubes. So, the malpigian tubes, the ones which are used to remove waste products from the insects. After that, we have buds, we have reptiles, we have mammals. Basically, the organisms and our phylum, codata, basically the organisms, okay, these are different classes of eggs, class reptilia, class mamalia for the mammals. So, this ones use the kidneys, they use the lungs, they use the skin to remove the different waste products from their body. So, apart from that, we have now the arachnids. So, the arachnids, they basically use the buclang. For example, we have the ticks, for example, we have the fleas, for example, we have the spiders. So, the arachnids, so these organisms, they use the buc lungs as their organ for excretion of waste products from their bodies. So, apart from that, we now have the amphibians. So, the amphibians, they basically comprise the frogs, the salamanders, the toads, etc. So, for the amphibians, they basically use the kidneys, they basically use the lungs, they use the liver, they use the gills to remove different waste products from their bodies. So, apart from that, we have platyhelmintes. So, platyhelmintes mainly comprises of the tapeworms. So, the platyhelmintes, they basically use the flame cells in order to remove waste products from their body. So, apart from that, we also have fish. So, the fish uses gills to remove waste products from its body. So, basically the gills. In gills' exchange, we studied about how the gills are able to remove waste products from the bodies of the fish. So, if you did get that, you can go back to the videos, the video classes of gills' exchange and see how the gills are used to remove waste products from the fish. So, the main process by which waste products are removed from the gills of the fish, we saw that it was counter current flow of water. So, you can go back and watch that video again if you are not familiar with the counter current flow of water. So, apart from that, let us now begin with the first one, excretion in mammals. So, how does excretion take place in mammals? So, this is a mammal. So, why are they called mammals? So, they are called mammals first of all because they give birth to living organisms. So, they give birth. So, apart from that, they also have mammary glands. So, if they have mammary glands, so they are also fit to be called mammals. So, those are the organisms which are referred to as mammals. If an organism gives birth, if an organism has mammary glands, so those are the ones which are referred to as mammals. So, now let us look at excretion in mammals. So, how does excretion take place in mammals? So, you see that excretory products in human beings include the lungs, not products, the excretory organs in human beings, mainly include the lungs, the skin, the kidney, the liver. So, these are the main excretory products for human beings, the lungs, the skin, the kidneys and the liver. In gases exchange, you also studied about how lungs are able to remove excess carbon-foxed and excess water vapour from the body. So, you can go back and watch that video of gases exchange to be able to understand in detail how the lungs are able to remove these waste products. So, let us begin by the lungs. So, lungs, you are going to discuss it briefly. So, for the lungs, you see that this is mainly found in mammals, like for example, in mammals, birds, reptiles and amphibians. So, these are the organisms whereby you can be able to find the lungs. So, for the lungs, you see that they have the air sacs which are called the alveoli. So, these alveoli are made up of thin elastic epithelium, mainly made up of capillary, so by in these capillaries, these are by respiratory gases are going to exchange. Respiratory gases that is carbon-foxed and oxygen. So, they are going to exchange through the process of diffusion. So, through the process of diffusion, these respiratory gases in the capillaries found in the alveoli are going to exchange in the process called gaseous exchange. So, you see that blood around the alveoli is of high concentration than the surrounding alveoli. So, this blood surrounding the alveoli is of high concentration of carbon for oxide. So, the air that is being breathed in is of high concentration of oxygen gase. Now, since the blood in the alveoli is of high concentration of CO2, the oxygen coming in, the air coming in is of high concentration of oxygen. Therefore, through the process of diffusion, the carbon for oxide in high concentration in the blood is going to move outside whereby its concentration is low. And then, oxygen since in the surrounding air is of high concentration than in the blood capillary. So, oxygen is also going to diffuse from the surrounding air and into the blood capillary swear its concentration is low as you can look at this diagram. So, this diagram explains exactly how it looks like. So, you can see the alveoli and then you can see also the blood coming in, the blood rich in carbon for oxide. The surrounding air you can see it is rich in oxygen gase. So, exactly what happens is diffusion process. Diffusion remember say that molecules are moving from a region of high concentration to a region of low concentration. So, exactly what happens is that since the carbon for oxide concentration in the blood vessel is very high. And then in the surrounding air it is very low. Carbon for oxide is going to move from the blood vessel, its concentration is high and into the surrounding blood where its concentration is low. Since the surrounding air is rich in oxygen gase. So, oxygen gase is of high concentration in surrounding air than in the blood capillaries. So, the oxygen gase is going to diffuse from the surrounding air whereby its concentration is high and into the blood capillaries whereby the concentration is very low through the process of diffusion. So, that is exactly how gase is exchanged takes place through the lungs in diffusion process. As you can look at this diagram, so this diagram which shows now the lungs and then we have the bronchus, the wind pipe, etcetera, etcetera. So, in this diagram you see that the carbon for oxide is removed from the lungs through the process of exhalation. So, if this person excels, remember the process of exhalation what you do see? The process of exhalation you see that the diaphragm, therefore moves up. After diaphragm moving up, the rib cage also moves inside. After the rib cage moving inside you see that the lungs are going to become small. If the lungs become small, air is going to be forced out of the lungs and into the surrounding environment. So, air will be forced out of the lungs where the pressure is high and into the surrounding environment where the pressure is low. That is now the process of exhalation that is the exhalation process now.