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Placenta | How do organisms reproduce

Let's learn how placenta helps in nourishing the fetus. Created by Mahesh Shenoy.

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Video transcript

in humans after fertilization the baby keeps growing inside the mother's womb for about nine months so as the baby grows its energy demands it's nutrition demands keep on increasing where does it get it from well it has to get it from the mother but how does mother keep up with all the required nutrition for it and similarly the baby has to get rid of the waste products that it it produces so how does the mother ensure all of that well to take care of all of this a very specialized tissue gets generated and that tissue is called the placenta as you can see over here so in this video let's look at placenta in a little bit more detail and see how it and nourishes the baby so the placenta is a very special tissue it's a disc-shaped tissue it doesn't look like discs from this angle but let me show you the image of an actual placenta and you can kind of see it is disc shaped this is the same car that is coming out of the placenta as you can see over here this is you may be familiar with this it's the umbilical cord it's the one that connects to the belly button eventually and of course listen does this is not really black I have made it black and white because I don't like to see blood a lot so anyways it's a specialized disc shaped structure if we need to understand the structure of it we may have to zoom in a little bit so let me zoom in here it is a small portion of the placenta zoomed in you can now see some of the blood vessels over here right so this is the blood vessel from the mother it's coming from the mother so this is the mother's blood vessels and this is the blood vessels of the baby which eventually goes into the umbilical cord and so the speciality of placenta is that contains both the mothers and the babies blood vessels meaning it contains both the cells of the mothers and the babies in other words it convinced both the DNA of the mothers and the babies that's the speciality of placenta so let's see how the placenta helps baby get everything so let's zoom in a little bit further so if I would take a small section of that and zoom in all right now we can see it better so we're here like I said these are the maternal blood vessels so let me write that down so this is the mother's blood vessels mothers blood vessels I'm just going to be v for blood vessels what do they do well you can see from the blood vessels you have tiny vessels coming out and they eventually end over here they open not an sorry they open into this region right into this region so what they do is that they basically start putting the blood into the region that's what the mother's blood was to do they fill this entire region up with her blood all right this whole region gets filled with the mother's blood so this is where you have let me write that as well this is where you have this whole region contains mother's blood so this will be the mother's blood that fills up this entire space this whole thing is filled with mother's blood and then these are the babies blood vessels so these let me write that in blue these represent the baby's blood vessels baby's blood vessels and so how does the baby get its nutrition well we can see all the deoxygenated blood coming over here this is all the deoxygenated blood that the heart is pumping away the baby's heart is pumping it away from its body all the deoxygenated blood which contains carbon dioxide may be it also contains all the waste products so all of that comes over here and then it comes very close to the metal blur as you can see these blood vessels eventually become very thin they become capillaries and they come very close to the maternal blood they don't come in contact with that you can see there are structures over here to prevent the contact there is no contact but they come close they come so close that diffusion starts happening and so over here what you will now find is that all that waste product all that carbon dioxide gets diffused out all that waste product gets diffused out all of that okay all of that waste product gets diffused out and all the oxygen starts getting diffused in all the glucose and the nutrients start getting diffused in and as a result of that the dioxide bed gets converted to oxygenated blood the maternal blood oxygenates the baby's blood by diffusion and now we have this rich oxygenated blood full of nutrients and that blood is now carried by this vessel all the way all the way to the baby's heart and then the baby's heart can now start circulating that for the entire baby the entire body and then the cycle repeats all the deoxygenated blood is again pumped out of the umbilical cord to the placenta gets deoxygenated and the cycle repeats and so to increase the amount of exchange that can happens to increase the area over here we have these finger-like structures and these finger-like structures are what we call the villi you may have heard of this in our intestines also we have villi again the whole idea is to increase the surface area the more surface area you have the more chances of exchange happening and as a result the faster this whole process becomes now one side note before we continue an interesting side note if you observe carefully you can see the blood vessel that carries the blood away from the heart this one the blue one which I've shown over here that's carrying the blood away from the heart that blood vessel usually what we call the arteries arteries are the one that carries the blood away from the heart right but notice the artery over here is carrying deoxygenated blood right mostly we like to think that arteries carry oxygenated blood but I humbly cook all the arteries carry deoxygenated blood and then the bloody it's oxygenated and then it flows back to the heart and so the veins in the umbilical cord carry the oxygenated blood all right just like in our pulmonary system just like in the system where action happens in our lungs they're also the same thing happens the arteries carry the oxidated blood deoxygenated blood sorry and the veins carry the oxygenated blood so the placenta kind of also plays the role of the lungs because the baby's lungs are not fully developed over here and now this blood which is getting more oxygen which is getting all the waste products from the baby this blood will be continuously recycled so this blood will be taken up by the mother's blood vessels and that blood will now go for all the filtration process for all the oxidation process and at the same time fresh new blood will keep on filling this pool so the pool of the blood will always be continuously recycled we want to make sure this is always rich in oxygen always rich in all the nutrition and so our baby keeps growing this way for about nine months in the mother's belly getting all the nutrition all the oxygen that it needs from the placenta and finally it's ready you usually see that the head will be positioned this way to come out first usually at least for normal deliveries at least and then the uterus will start giving its rhythmic contraction meaning the top part will contract and at the same time the bottom part will start relaxing another result the baby's head will get pushed out of the vagina and so the baby's head comes out first and then the baby's body comes out and then then doctors usually cut the umbilical cord and the baby is out but to end the delivery you know what happens finally the placenta is shed out that's the end of delivery the percenter is not needed anymore once the baby is out right so the delivery concludes with the shedding of placenta the placenta finally comes out of the vagina and so long story short placenta is a special disc shaped tissue which contains both the blood vessels of the mother and the blood vessels of the baby it's responsible for nourishing the baby for the entire nine months providing it with all the oxygen the nutrition and also removal of all the unwanted stuff like carbon dioxide the waste products from the baby's body and how does it work well the mother's blood vessels continuously keep pouring him fresh oxygenated blood with all the goodies all the nutrients in this particular space which we can say is the mother's blood pool and the oxygen and all the nutrients from that gets diffused into the baby's blood vessels and that's how the baby gets all the oxygen and nutrients at the same time all the unwanted stuff gets diffused in that same blood from the baby's blood vessels that's how the baby gets rid of all the unwanted stuff the finger-like projections which are called villi increase the surface area to increase the amount of exchange that happens and finally the mother's blood is continuously recycled getting rid of all the deoxygenated blood and resupplying it with all the oxygenated blood