The blood circulation of the fetus is arranged in such a way that the needs of its development are fully provided. The circulatory system at the time of birth is undergoing certain changes. With the first breath in a newborn, a rush of blood to the lungs occurs and the usual type of blood circulation appears, which differs from intrauterine.
The process of embryo heart formation begins in the second week of pregnancy, and its formation ends in the second month of fetal development. In this period, it acquires all the features of a four-chamber heart. Together with the formation of the heart, the vascular system, blood circulation of the fetus develops. He receives oxygen and nutrients from his mother. Therefore, there are certain features of the blood supply to the unborn child.
How does the blood circulation of the fetus
Blood saturated with oxygen comes from the placenta through the umbilical vein. In this case, approximately half of the blood is discharged from the umbilical cord through the venous network of the fetus. The discharged blood passes the vascular system of the fetal liver and enters the inferior vena cava. The rest of the blood enters the liver through the portal vein. Then it rushes through the veins of the liver into the inferior vena cava.
As a result of such features of blood circulation, the blood in the inferior vena cava is mixed. The oxygen content in it is greater than in blood returning from the superior vena cava to the atrium (right). This is a very important aspect, since both blood flows in the right atrium are separated, which means that they have different paths.
The blood supply to the fetus due to the separation of the directions of blood flow has the following features: its brain and myocardium are provided with blood with a high oxygen content. And less oxygenated blood enters the placenta through the descending aorta and umbilical arteries to saturate with oxygen.
The blood entering the right atrium (its greater amount) from the inferior vena cava through the oval hole is sent to the left atrium. Oxygen-rich blood is discharged due to the lower edge of the secondary septum. This partition is called the Eustachian damper. It is located above the opening leading to the right atrium from the inferior vena cava.
Next, the process of mixing the incoming blood with a small amount of insufficiently supplied oxygen is returned through the pulmonary veins of the fetus into the left atrium. From the left atrium, blood moves into the left ventricle, and then is thrown into the ascending aorta. And already from the aorta, the oxygen-rich blood flow is distributed in three directions:
1. In the coronary arteries for the implementation of myocardial perfusion. This is approximately 9% of blood ejected from the left ventricle.
2. Into the brain and upper torso. The amount of such blood is about 62%. It enters through the carotid and subclavian arteries.
3. In the descending aorta, then in the remaining organs of the fetus. The volume of this blood is 29%.
Thus, the blood circulation of the fetus. Its proper intrauterine development depends on many factors: the heredity of the expectant mother, her lifestyle, nutrition, etc.
Fetal size
In parallel with the process of development of the fetus , an increase in its size occurs. It is growing every hour, every day. Until twenty-one weeks of gestation, the fetus is measured from the parietal to the sacrum. After this period, measurements are taken from the head to the heels. Knowing the size of the fetus, a woman can monitor how timely it develops.
The development of the child depends, among other things, on the weight gain of the expectant mother. Therefore, it is necessary to strictly observe the diet recommended by the doctor. In addition, you need to perform a set of special physical exercises. Compliance with the future mother of all the prescriptions of specialists will help the fetus develop in accordance with the terms.