now for chapter 8 what we're going to be looking at is uh the transport in mamals under animal transport it can be quite confusing because the transport in fish the transport in insects and also the transport in mammals will have um differences between them so for the purpose of chapter 8 we are just going to be consider concerning ourselves with what is happening in mammals all right we're not going to go into fish or insects now before we go into the detail of this we have to ask ourselves the question what is a transport system and the next question is why do we need it so before we ask ourselves this question over here we will then have to go through a little bit of a situation again like I always like to do I like to give ourselves a bit of a situation so that we understand um why we need what we need let's assume this over here is a unicellular organism now the meaning of the term unicellular organism it just basically means that it is made up of one cell right and of course if I'm drawing out a multicellular organism the meaning meaning of the term multicellular organism is it is just basically made up of many cells now what trying to understand these organisms in a three-dimensional view can be a little bit difficult so what I'm going to do is I'm going to represent them in a two-dimensional view instead in a two-dimensional view if we were to just basically draw this out this is the unicellular organism right here and again it is made up of one cell but the multicellular organism however will be made up of many cells okay now as you can see the unicellular organism is on the left and for the multicellular organism I've highlighted a particular cell in the middle right there I hope you can see that where I have highlighted in yellow let's assume that both these cells require the same type of substances to survive for example both of them may require oxygen uh to carry out aerobic respiration so oxygen is something the cells need in order to survive how do they receive oxygen then okay they receive oxygen I'm just going to represent the oxygen as just basically this little dots over here so these are just oxygen molecules so for the unicellular organism the thing here is the oxygen can just basically diffuse into the cell very easily okay now here is where it's going to be a little bit difficult right because let's for example say the oxygen molecule is over here okay can it easily diffuse all the way into the cells in the middle so the cell that have highlighted also needs oxygen but oxygen is is not able to diffuse very easily into the cell the reason is because it's due to its great distance okay the great distance over here will prevent the oxygen from reaching the cells so what will happen to this cell this cell will then die okay so the cells in your M the cells in the multicellular organism especially when they deep into the organism because we have many layers of cells right it's very difficult for them to receive oxygen so we have a problem over here and the problem is how do these cells then receive oxygen or any other nutrients for that matter so to remedy this problem we evolved to have a transport system then of course what exactly is the transport system very simple the first thing that actually happened is perhaps we don't know for sure which happened first okay the inside of our body start started having cavitations or spaces okay then just going to dra like a simple space like this okay hopefully you can see that now once we've actually created the space that's not enough what they actually started to do was they also filled up that area with a kind of liquid okay they also filled up the area with a kind of liquid so now students will be like oh why do they fill up that area with the kind of liquid and to make sure that the liquid does not just spontaneously leak out because this liquid is important we put the liquid in a kind of tube or a kind of container basically and that container I'm representing as uh I hope you can see the orange color okay it's not so thick okay in this case like an orange color so the liquid will just remain in a kind of tube basically and so how does this help well let's look so let's say this is the oxygen molecule over here okay the oxygen molecule the oxygen molecule can diffuse into this area so now the oxygen is inside the medium it's dissolved inside the medium okay whatever this medium is right we'll talk about that in a while and then but but look at the distance between them they are still quite far away aren't they okay the distance is still quite far away so what needs to happen is the oxygen needs to move and that's where the cell creates another component of the transport system and the other component of the transport system is referred to as something called as a pump and what this pump will start to do is this pump will basically start to move okay this pump will start to move and it will just basically start pushing the liquid and as it starts pushing the liquid as it starts pushing the liquid what happens is the oxygen molecule inside the medium will just start moving and now when it's very near the cell diffusion can easily happen so compare without the transport system the distance was very far but with the transport system the distance between oxygen and the cell is very near so the transport system it transports substances to the cell as nearly as possible why do we need the transport system it's very simple we need the transport system because it transports substances to the cells as nearly as possible because without the transport system it will be too far away now what are the components of the transport system okay this is what we have to see so what is the transport system actually made out of in mammals the transport system is basically made up of this so-called medium which is this liquid inside here and that Medium is called blood the blood is the thing that is required to carry the substances then what we also have is the blood is actually within something called blood vessels the blood vessels are needed to contain the blood to make sure that the blood does not just leak out of the body of the organism and the third most important thing to make sure that the blood is constantly moving is the pump and you guessed it the pump over here is basically referred to as the heart these are the three main components of the transport system that we are going to be looking at in this chapter the heart the blood and also the blood vessels so just to summarize in this case over here you have two multicellular organisms so in the case of this multicellular organism the one on the left it doesn't have a transport system the one on the right has a transport system so the one on the left because it doesn't have a transport system the substances such as oxygen will have difficulty diffusing all the way into the cell because the distance is too far but with the help of the transport system oxygen can go into the blood blood is pumped all the way towards the cell and then the distance of diffusion is minimized that is what the transport system basically does the transport system basically minimizes the distance required for diffusion to happen making it easier for cells in multicellular organisms to receive whatever substances and also to give up Wast by the way okay so this is the importance of the transport system