 Now, we take example of a simple multicellular organism, simple multicellular organisms. For example, Hydra, an Idaerian, Cylintrate. Hydra is a multicellular organism, have two layers of cells called actoderm, the external layer and endoderm, the internal layer, as you can see in the diagram, and it have a cavity inside its body, sometimes called a gastrovascular cavity, and it have an opening in the center, it's one opening, because it is living in the water, water can move inside the cavity to the mouth, we call this opening a mouth or an anus as well, because this is both for intake of water and removal of water. So, water enters through this opening, moves through the whole gastrovascular cavity, distributes the food materials, there are cells present inside the internal layer, we can call the endoderm, which entrapped the food particles and removes their waste products into that water, and then that water goes out through that opening by a pressing action of the gastrovascular cavity, and then water comes again inside. So, this is the transport system of a hydra, simple multicellular organisms have transport systems like this, now we take example of complex organisms, the plants and animals, plants have roots to absorb water and food from the soil, then after roots they have stem, and upon the stem they have leaves, they have to transport materials from their roots moving above towards their stem, and from the stem moving towards the leaves and so on, they have different types of transport systems, we look at a diagram, here you can see in the diagram the movement of water from a root here, because roots have hairs to increase the surface area for intake of water, root here, from root hairs you can see that water moves towards the central part of the root, and then it enters a specific tissue called xylem, which makes tubes, strong tubes for the movement of water, the xylem tissue then move that water up, conduct that water towards the upper branches and the leaves and all the parts of the plant, just like that there is another tissue called phloem, which is more for absorption of food materials from the soil, and it help in movement of the food materials upside, then the plants in their leaves they have some specific types of cells, called God cells, which makes stomata, that is parts of the leaf which can when they swell up, they open the pathway and expose the internal part with the environment, the stomata inside the leaves present in the leaves, open the leaves actually connect the leaves with the external environment, this process is for removal of water from the inside of the leaves towards outside, which is called transpiration, due to transpiration what happened that when water goes out, then a pressure is built up below the stomata in the leaf tissues, which result in movement of water from the xylem tissue towards the leaves, and this pressure goes down to the roots and due to this pressure water moves upside from the roots to the stem to the leaves and so on, so this is another movement or transport in the plants, transport of sugar molecules also occur in the plants, as you can see in this diagram that leaves have veins inside, leaves have we can say pathways or canals in which the food materials can move, the sugar molecules are transported by an active transport from one part of the leaf to another part, as you can see in the diagram by an active transport that is they have to utilize ATP for this transport, so plants also have different types of transport systems through which they transport their food from the roots to the stems, from the stems to the leaves and other parts of the body, so that they manage their metabolism and their functions, now we come on animals, animals have a system called circulatory system for transport, animals are comparatively more complex than all other life forms, because they are complex they have to face more challenges, they need a more efficient and more co-ordinate transport system, animals evolved two types of transport systems an open circulatory system and a closed circulatory system, we call it a circulatory system because this is for the circulation of materials within the body and sometimes sometimes they exchange with the environment when it is required, there are two types of circulatory systems in animals open and closed, here you can see in a diagram a comparison of an open and closed circulatory system, on the right there is an image of an insect, a diagram from an insect, on the left there is a diagram of an earth form, in the insects there is an open circulatory system that exists for circulation or for transport, as you can see that there is a series of hearts above that in the towards the dorsal side of the body, sometimes there is one heart, sometimes there are more than one heart, heart is a pumping organ which have to pump the fluid from one part of the body to another, sometimes they have more than one heart, sometimes they have one heart, but whatever to heart you can see that lot many vessels tubes are connected, but if you closely observe you can see that these tubes are open from one end, towards heart they are connected to the heart, to the hearts actually and towards the other side they are open, when the heart pumps the blood, when the heart contracts then the blood which is actually the circulatory fluid of these organisms which is called sometimes hemolyme because this is not like the human blood, this is a different kind of circulatory tissue, liquid tissue we can say, we call it a hemolyme, when the hearts pump then they push that blood towards the body and through these vessels blood moves into the body cavity and bath all the tissues of the organism, then due to the contraction of the muscles of the body, forex and abdomen, this blood is pushed back into the heart, through the vessels and then heart pump again, so it is a open circulatory system because this is open from one side, towards heart it is closed, but towards other side it is open and open directly into the body cavity, the other system is called closed circulatory system, as you can see in the next diagram on the left this is the diagram of an earthworm, earthworm has a closed circulatory system, it have hearts which are pumping organs which have to pump the blood, contract and relax to throw the blood towards the body organs, but as you can observe that it have a ventral vessel in a dorsal vessel and a small vascular network which is called capillary network, in this system actually blood never leaves the network of vessels, blood always stays inside the network of the vessel, so we call it a closed circulatory system that is circulatory fluid never leaves the network of the vessels, whether we call them capillaries the small ones or larger vessels or whatever, except for there is an injury, there is an injury to the vessel then of course blood will go out, but otherwise blood always remain inside the heart to vessels to small vessels and back to heart and so on, so this is the difference between a closed and an open circulatory system, now we talk about this the human circulatory system, humans as we know are the most complicated organisms on earth, have most complicated body systems, have most advanced metabolic pathways, so they have to face more more challenges, they have to manage their metabolism, they have to acquire food from the environment and distribute that food to actually millions and billions of cells, they have to distribute their hormones their enzymes and all the materials in different parts of cells which are so far away from heart, which are so far away for the vessels, which are so far away from each other, so human circulatory system is very much complicated, human circulatory system consists of blood, the circulatory fluid, blood is a liquid tissue, it is a connective tissue and it is overall liquid, though it have cellular content, the blood circulates or moves or flows inside the vessels, the vascular system, the vessels are of different kinds according to the requirements of different parts of the body, vessels are of different, they have different structures, we will talk about them and then the heart, the pumping organ, heart in human beings is of course the most complex and the most coordinated, it have to coordinate with the vessels and with the other organs according to the requirements of the body and it have to pump the blood towards all those parts of body which are far away, which are more complicated, they have to distribute materials for all of the body organs, so human blood vascular system consists of three major parts, the blood which is circulatory fluid, liquid tissue, the blood vessels, we call them sometimes the vascular system and the heart which is the pumping organ, sometimes we also call it a cardiovascular system that is cardio stands for heart vascular for vessels, so cardiovascular system is the transport system and circulatory system in human beings, in this lecture we are going to talk about the blood, the circulatory fluid which is quite highly complex and have various kinds of materials, cellular ones and non-cellular ones, we are going to talk about blood in next section, so the blood, the circulatory fluid, what is blood itself? Blood is a watery fluid which have different types of dissolved and undissolved contents present inside, blood itself consists of two, we can if we want to categorize its contents we can divide them into two major categories, the plasma, the fluid which have dissolved and undissolved materials and the cellular contents, the cell or cell like bodies present inside the blood which are the red blood cells, we call them RBCs for ease to abbreviate, the white blood cells or the WBCs, the platelets which are not the cells but which are fragments of a single cell called mega karyosite, the average human body have about five litres of blood, so it may vary with the weight of the body and weight of the person, the blood is about one-twelfth part of the whole body, whole body's weight and mass, the contents of the blood could be separated based upon their weights and densities, if we want to separate the cellular content with the non-cellular contents and red blood cells with other cells or white blood cells we can do it, if we can do this by adding a heparin or some solution which can stop the coagulation of blood and if we let that blood by adding anti coagulant that will actually stop blood from clotting and let it stand for some time or centrifuge, the plasma and the cellular contents they separate and they will look like something like I'm showing you, look at this diagram, the first one on the left is a blood simply just taken away from the vein and an anti coagulant added, if we let it stand for some time or we centrifuge it on a specific speed, we can get its content separated in layers as you can see in the diagram on right, the top one is the plasma, the fluid content of the blood, the second layer, small one is the layer of white blood cells and the platelets and the third the bottom layer which is quite a large one consists of RBCs or the red blood cells, so red blood cells settle down due to their higher density, white blood cells and platelets settle up and then the plasma settles on the top, so we can separate experimentally if we want to separate the contents of the blood, now we'll talk about their properties, properties, characteristics and functions of various parts of blood, first of all the plasma, the fluid content of the blood, it consists of 55% of the blood means that 55% of the blood is the plasma, the fluid, the watery fluid, then comes the cells, cellular content or we can call them cells and cell-like bodies, they consist of another 45% of blood to make it a hundred, so 45% of blood is cells or cell-like bodies, it includes the blood cells, red blood cells, white blood cells, platelets, now we talk about them one by one, the blood plasma, blood plasma is a watery fluid, it is about 92% water, 92% of blood plasma is water, then it have different types of dissolved materials, as the slide shows, 0.9% of the plasma is salts, sodium chloride just like that of our table salt which we use in our dishes and it is also present inside our blood, different types of salts of magnesium, zinc, different types of ions, sodium, potassium, zinc, magnesium are present inside the blood dissolved or undissolved states, what is the function of these ions or in these salts, these ions and salts actually maintains the pH of the blood, pH of the blood is roughly 7.4 and if some concentration of some of the salts is changed in the blood due to any reason, maybe a hormonal change, maybe an environmental change or something, then the pH of blood will change, maybe towards acidic or maybe towards alkaline which is dangerous for the body and body have to maintain that pH back by adding the salt from some of the sources, then sometimes you know the blood pressure is also affected due to the concentration of sodium, you know that if your blood pressure drops down sometimes you feel unconscious and someone who knows comes and says that okay take a glass of water with some dissolved salt and your salt and your blood fills in back and your blood pressure is retained to normal, the second thing is proteins, proteins in plasma are from 7 to 9% 7 to 9% content or part of plasma is proteins, different types of proteins, antibodies, fibrinogen and albumin to name some important one, antibodies makes the immune system of the body, you know that body is always exposed to its environment and surrounding, it is exposed to infections, bacteria, virus parasites, different types of organisms, these antibodies are those specific cells which can react against any type of invader particularly those bacteria and virus, the infectious agents and trap them inside and kill them and remove them, so antibodies are actually part of the immune system or defense system of the body, fibrinogen, fibrinogen is the clotting factor of the body, it helps the blood to clot, when there is a need to push, when there is an injury for example, some part is injured and there is a seeping of blood out then fibrinogen help in clotting of the blood, albumin is also an important protein, it helps the blood in maintaining its water balance, so and there are a lot many other proteins which are always circulating inside the blood, many hormones are always circulating the blood or they are released when required, many enzymes are circulating inside the blood, many different types of proteins circulates in the blood all the times, according to the requirements of the body and they are distributed by the blood to various parts of the body, for example a hormone, a growth hormone is released from the pituitary gland and it have to move through the whole body and reach almost all tissues of the body, particularly when a child is growing, it have growth hormone quantities and large quantities and which have to be distributed in all of the body tissues to make them grow, so blood have not many proteins, different types of proteins, then blood also have lot many the plasma have lot many different other particles like digested food particles, the nutrients for example, carbohydrates when they are digested they are converted to glucose, glucose have to be distributed in the body, this is in the blood, this is distributed through the blood to the different tissues, the cells different hormones as I have previously mentioned have to be transported by blood, the metabolic waste products, when the cells they to the metabolism and particularly the catabolism, they produce many toxic byproducts, these toxic byproduct have to be transported to specific part of the body, for example liver which destroys them or convert them to less toxic forms from the further removal of the body, so there are lot many other materials which are present inside the blood, according to the requirement of body at that particular time, there are respiratory gases, for example, oxygen always circulates in the blood, because blood have to circulate oxygen and distribute oxygen to all the cells of the body, each and every cell actually, because cells without oxygen they cannot produce their energy, they cannot live and the product of respiration is carbon dioxide which have to be instantly removed from the tissues, so blood also have carbon dioxide which it have to give back, have to remove from the body through the respiratory system, here is another diagram which is just simply showing different types of contents of plasma, the blood cells and different types of blood cells, as you see plasma, the liquid part, dilute solution of source, glucose, amino acids, vitamins, urea, proteins and fats, then second layer is the white blood cells which is involved in the immune system of the body, third is then the platelets which are involved in clotting, the red blood cells which are involved in carrying oxygen, so this diagram is just showing which constituents are present in different parts of the blood cells and cell like bodies, blood have different types of cells, we name them also differently, we have erythrocytes, leukocytes and thrombocytes, erythrocytes are also called the red blood cells, leukocytes are also called the white blood cells and platelets and the thrombocytes are also called the platelets, the very famous platelets due to the dange fever, we talk about them one by one, erythrocytes, the red blood cells, they looks red, as you see red, they looks red due to presence of particular protein with an iron group inside hemoglobin, red blood cells have hemoglobin molecules inside, function of the hemoglobin molecule is to carry oxygen, so red blood cells carries oxygen from various parts of the body and distribute them to the tissues, the red blood cells also carries carbon dioxide, these actually removes carbon dioxide from, carbon dioxide molecules from different tissues, the cells and return them to the respiratory and cardiovascular systems to deal with, the red blood cells are present in the highest quantity inside the blood, so the most common cells in the blood circulatory system in the blood are the red blood cells or the erythrocytes, in men these are present in a millimeter cubed, these are present as 5 to 5.5 million cells, so in men RBC's red blood cells are 5 to 5.5 million per millimeter cube, you can guess how many these are, in women these are from 4 to 4.5 million per mm cube, so these are in extremely large quantities, very high quantities and of course these are required because they have to transport carbon dioxide and oxygen to the billions of cells present inside the human body everywhere and for doing this they have hemoglobin molecules, hemoglobin molecules have an iron group inside and it's a large, it consists of large polypeptide chains which can get, which can attach to the oxygen molecule and transfer it to the different tissues.