 In this lecture, we are going to talk about the transport systems in living organisms. And we are specifically talking about the circulatory fluid, the blood in human beings. We will concentrate on the blood circulatory fluid and its contents in human beings. To start with, what is transport and why the transport systems are required? Why transport system? Why the organisms need a transport system? Organisms have to exchange materials with their surroundings, with their environments. Because they have to live in the environment, sustain themselves in the environment. They have to exchange materials from time to time with the environment. Also, they need to distribute different materials present within their own body, from one part of the body to another part of the body. And they have to sometimes remove their metabolic waste products. For all of these things, they need transport systems which can transport materials from the organism to the environment and back. And from one part of the body to another part of the body and back and so on. The living organisms have to acquire energy or food from the environment. Then they have to distribute that food or that energy to all parts of their body. Organisms need an intake of different gases, particularly oxygen. Intake of air that includes oxygen. They need to remove carbon dioxide from their body that is produced as a by-product or waste product of the respiration process. They need to remove the metabolic and toxic wastes, the toxic materials which are produced as a by-product of metabolism and also some other toxic materials which are somehow invaded the body or which are produced by the metabolism. Which are the products of catabolism. They have to sometimes move these particles, these toxic or maybe unwanted particles from one part of the body to another part of the body and then they have to release it into the environment. They have to distribute hormones, other chemicals, enzymes from sometimes one part of the cell to another part of the cell, sometimes from cell to blood and from blood to other organs. Organisms also have to exchange materials with the environment. That is products of their metabolism, the toxic waste, the nitrogenous waste in all. For all of these things organisms need a transport system that can exchange materials with the environment and within the body of organism from one part to another part. Now as we know that organisms are of various kinds. There is a huge variety of organisms present in the universe in the biosphere. Organisms are very small from unicellular to very very complex multicellular as us human beings. Some organisms are very small just consist of one cell unicellular. For example amoeba. Amoeba is a unicellular organism that consists of only one cell. It also have to exchange its materials with the environment and it is exposed directly to the external environment and it have to exchange all the materials with the environment. And we have simple multicellular organisms which are larger but which have simpler layers of cells which makes their body. For example sponges which have two layers of their body which have two layers of cells which makes their body. The octoderm and the anoderm. These also have to exchange materials with the environment. Their way is different from that of unicellular organisms and we have organisms which are as complex as the higher plants and the animals which have lot many cells. Millions or billions of cells in their body and they have to exchange materials from maybe thousand cells million cells have to exchange materials with each other and with the environment. So the transport systems are adapted according to the need of the organism that how complex is the organism and in which environment it is living. If we look at the diagram of an amoeba. Amoeba as we know is unicellular organism and lives in fresh water. It have to exchange its materials though its functions are simple. It have to take food from the environment, acquire food from the environment and it have to remove the toxic waste of metabolism and it have to distribute the food acquired from the environment inside its body. For this purpose amoeba makes food vacuums. When it get to touch a food particle in a smaller organism maybe then its membrane its cell membrane invaginates and due to this invagination it entraps the food particle inside with some water. This is called a food vacuums. This food vacuums then due to the cytoskeletal elements present inside the amoeba's body the cell moves from one place to another place inside the cell. There are different types of cytoskeletal elements which help its movement. For example the actin filaments which are also called the micro filaments which help in movement of this food vacuums from one place to another place and with the time being a lysosome come pour its enzymes and food is digested then the vacuums moves inside the body due to this cytoplasmic movement with the help of cytoskeletal filaments, the micro filaments and distribute that digested food in the body. Then it have to remove water from its body because its living in fresh water. It is exposed to a lot, much quantity of water. So a hypotonic solution we can say. So what could happen? Water rushes inside its body because salt concentration is more inside. Water moves inside. To get at the situation amoeba have another transport system called contractile vacuums which fills up with water which absorb water from its surrounding inside the body of amoeba, fills up with water. When it fills up then it removes through a pour that water outside the body. It have a pour, it is associated with a pour in the cell membrane and when it is filled it removes the water towards surrounding. It is continuously actively doing it with the help of ATP as energy. So even unicycle organisms they have certain transport systems which help them in transport of materials.