Today, the term "placenta" does not surprise anyone. Modern girls are much more aware of pregnancy and childbirth than their grandmothers and mothers. However, most of this knowledge is superficial. Therefore, today we want to talk about what the placental barrier is in the womb. At first glance, what is incomprehensible here? The children's place has the ability to protect the developing embryo from the harmful effects and toxic substances. In fact, this body is a real mystery and a miracle of nature.
Protected
The placental barrier is a kind of immune system. It serves as the boundary between two organisms. It is the placenta that ensures their normal coexistence and lack of immunological conflict. The first trimester of pregnancy is the most difficult. Partly because the placenta has not yet been formed, it means that the body of the embryo is completely unprotected. From about 12 weeks, she is fully involved in the work. From now on, she is ready to perform all her functions.
How is the placenta arranged?
This is an important point, without which we will not be able to continue our conversation. The very word "placenta" came to us from Latin. It translates as “flat cake”. Its main part is special villi, which begin to form from the first days of pregnancy. They branch out more and more every day. At the same time, the blood of the child is inside them. At the same time, maternal blood enriched with nutrients enters the outside. That is, the placental barrier carries primarily a dividing function. This is very important, since this body regulates the metabolism between two closed systems. According to this statement, the external and internal sides of the placenta has a different structure. Inside, it is smooth. The outer side is uneven, lobed.
Barrier function
What does the concept of "placental barrier" include? Let's deviate a little more towards the physiology of the ongoing processes. As already mentioned, it is the unique villi that provide the exchange of substances between a woman and an embryo. Maternal blood brings oxygen and nutrients to the baby , and the fetus gives carbon dioxide to the pregnant girl. The excretory system while they have one for two. And herein lies the greatest mystery. The placental barrier separates the blood of the mother and the fetus so well that they do not mix.
At first glance it seems unimaginable, but the two vascular systems are separated by a unique membrane septum. She selectively misses what is important for fetal development. On the other hand, toxic, harmful and dangerous substances linger here. Therefore, doctors say that starting from 12 weeks the expectant mother can already relax a bit. The placenta is able to protect the body of the child from many adverse factors.
Only the most important
All the necessary nutrients, as well as oxygen, pass through the placental barrier. If the doctor observes the pathology of the fetal development, he can prescribe special drugs that increase the blood supply to the placenta. So, they increase the amount of oxygen that comes to the baby. However, not all so simple. The membrane septum retains bacteria and viruses contained in the mother's blood, as well as antibodies that are produced during the Rh conflict. That is, the unique structure of this membrane is configured to preserve the fetus in a variety of situations.
It should be noted the high selectivity of the septum. The same substances that cross the placental barrier cross this line in different ways towards the mother and the fetus. For example, fluoride very easily and quickly penetrates from a woman to a baby, but does not pass at all. A similar situation is with bromine.
What causes metabolic regulation?
We have already told the reader that the placental barrier separates the lymph of the mother and the fetus. How did nature manage to launch such a perfect regulatory mechanism when what is needed penetrates the barrier, and what is harmful is delayed? In fact, we are talking here immediately about two mechanisms. Next, a little more detail on each of them.
First of all, we are interested in how the intake of vital, nutrient elements is regulated. Everything is quite simple here. Lipids and carbohydrates, proteins and vitamins are constantly present in the blood of the mother. This means that the body can work out a balanced scheme. It will initially imply that the concentration of certain substances in the blood of a mother and a child is different.
Placenta permeability
It is much more complicated when we talk about toxic substances that enter the body of a pregnant woman. The placental barrier separates lymph and blood. This means that those toxins that have passed through the mother’s bloodstream will not reach the fetus in its pure form. However, after passing through a series of natural filters (liver and kidneys) in a residual form, they can still harm the baby. The fact is that substances (chemicals, drugs) that accidentally enter the mother’s body are much more difficult to stop. They often tend to cross the placental barrier.
Limited barrier function
Nature could not foresee the development of modern industry. Therefore, chemical products relatively easily pass the natural barrier. They threaten the growth and development of the fetus. The degree of penetration through the placenta depends on the properties and characteristics of a particular substance. We will note only a few points, in fact there are many more. So, drugs with a molecular weight (less than 600 g / mol) pass through the placental barrier much faster. At the same time, those that have a lower rate practically do not penetrate. For example, these are insulin and heparin, which can be prescribed without fear during pregnancy.
There is one more sign. Fat-soluble substances penetrate the placenta much better than water-soluble. Therefore, hydrophilic compounds are more desirable. In addition, doctors know that the probability of penetration of a substance through the placenta depends on the time the drug stays in the blood. All long-acting drugs are more dangerous than those that are rapidly metabolized.