 Next topic is placenta, which is a very important structure because it is the connection between the mother and the growing child. We will see its structure and function. What is placenta? This is the organ that sustains the embryo and fetus throughout pregnancy and through which gases are exchanged, nutrients are supplied and vests are removed from the fetus system to the maternal end. This is the placenta and this is the umbilical cord attached to the baby's navel. After passing through this placenta through the umbilical cord, placenta is a connection between the mother and the fetus. Now we will look at its structure in detail. The tiny finger-like projections that we saw in the previous modules are trophoblasts. Trophoblasts develop connections with the endometrium and that is the start of the placenta. This is the corionic villi, the corion that is the membrane. This is the corionic villi that penetrates into the endometrium. These blood vessels do not merge. It should be very clear that fetal blood does not mix directly with mother's blood. It is not that the mother's blood goes into the fetus or the mother's blood goes into the mother's blood. If this happens, that becomes a lot of problems. But this is not the case in normal cases. And it should not happen, in fact. So the placenta is a phyto-maternal organ. This is the uterine wall. And the mother's blood goes into the uterine. The red part of the uterine will be the oxygenated blood. The blue part indicates the deoxygenated blood. This is the uterine vein. And this is the uterine artery. So the mother's blood goes here. And here it becomes an island. There is a free blood that moves in the little tanks of blood. It circulates blood in the spaces. And in this part, in this blood, the corionic villa that divides and re-divide, becomes a branch structure. And from here, fetal blood is implanted in the mother's blood, in the villa that circulates. So we are seeing here that mother's blood is not mixing directly with the fetal blood. And another thing is that the umbilical cord is attached to the baby on the other end. So this is the umbilical cord. These are two umbilical arteries and one umbilical vein. This is the detailed structure of the placenta. So it has two components. So fetal part develops from the corionic sac. Material part derived from the endometrium to placenta and the umbilical cord is the system for transporting substances between mother and the fetus. Now branches of the mother's arteries in the wall of her uterus open into pools near the corionic villa. Now oxygen and nutrients from the mother's blood diffuses into the fetal capillaries of the placenta. Here simply because the islands or the pools have a branch structure of the villa. And the exchange, the diffusion, can also be active transport. So there is a supply of nutrients to the developing child. Okay. Next is the functions of the placenta. There is a gas exchange. After that there is a nutrition supply from the mother to the fetus. Then there is a hormone secretion from the placenta which is what we call prolectin and oxytocin. And the fetal, because there is metabolism in the fetus, it is also becoming a nitrogenous waste. And these nitrogenous waste are being removed that is from the fetus into the mother. And then the mother's blood comes in and then the mother's kidneys take it out. Now nutrients and drug transfer across the placenta are by passive diffusion. Passive diffusion that means the passive transport can also be called diffusion. That is movement from high to low concentration. If there are more nutrients in the mother's blood, then they will diffuse into the fetus through placenta. After that there is a facilitated diffusion. There is active transport. There is a movement from low to high concentration. If there are vital substances without them, life at risk, then there is active transport. And then there is penocytosis which is a special way of transport. Now the umbilical cord connects the placenta to the abdomen of the fetus through the navel. So two fetal umbilical arteries and one fetal umbilical vein that is parallel about each other in the umbilical cord. And in this we have seen in the umbilical cord that there are arteries and veins. Okay. Now oxygen and nutrients from the mother's blood diffuse into the fetal capillaries of the placenta. The fetal capillaries lead into the umbilical vein which is enclosed within the umbilical cord. Now from here the fresh blood circulates through the fetus that is the body. So from this we have seen that we have seen the structure. We have seen its definition. In fact, what is placenta? Placenta is seen in its detailed structure, blood circulation. And apart from that we have seen its function. We have seen that there are multiple functions of placenta. And nowadays there is a lot of research on placenta. There is information that it is being used for creating immunity in the mother and the public. So this is all about.