About growth and development of conception results
Normally, pregnancy lasts about 10 months or 9 months, or 40 weeks. The growth and development of the fetus strongly influenced by the health level of the mother. Also, the condition of the fetus itself and the placenta as the main tools providing any nutrition. The actual fetal age is calculated from the time of fertilization or at least from the time of ovulation.
The growth of conception results is divided into three important stages, namely the level of the ovum (age 0 to 2 weeks). The conception results have not yet formed any growth, the embryo between the ages of 3 to 8 weeks. They have been formed designs of instruments of the body. Later, fetus formed as humans in the age over 8 weeks.
There are several changes in circulation to the fetus such as changes in cord circulation, placental circulation, and fetal blood circulation. Below we have submitted the explanation:
- Umbilical cord circulation
The umbilical cord is located between the fetal center and the fetal surface of the placenta. The color is white outside formed a twisted rope. The length is around 55 cm (30 to 100 cm) and the diameter is about 1 to 2 cm. The umbilical cord is covered with amnion which is very tightly attached, consisting of 2 arteries and 1 vein. Consisting of substances such as jelly called selewharton which prevents compression of the blood vessels. Also, continuously feeding for the fetus can be guaranteed. Compression can occur if the cord is located between the fetal and pelvic head or twisted around the fetal body. The cord wrapped around the fetal neck is called the nuchal cord. This umbilical cord insertion in the placenta consists of:
- Central incisor (in the middle of the placenta)
- Centralized insertion (slightly to the side)
- Lateral insertion (located on the side)
- Insersio marginalis (on the edge)
- Velamentous insertion (located outside the placenta or in the fetal membrane)
- Placental Circulation
Embryo-placental circulation of the mother occurs usually on day 17 when the heart of the embryo starts pulsing. At week 3, the blood of the embryo circulates between the embryo and chorionous villi.
Blood phenosa (without oxygen) leaves the fetus through the umbilical artery and enters the placenta. Inside the villi it forms an arterial-capillary-venous system. This Villi is buried in lacuna (the spatial intervilosum). There is no mixing of blood between fetal venous blood and maternal blood. Arterial blood (oxygenated) enters the fetus through the umbilical vein. Maternal blood enters the intervillosum sperm by spraying. The high-pressure difference between the entry points of the blood (60 – 7- mmHg) with the pressure between the villi (20 mmHg) causes the blood rotating around the villi. Gas and nutrient exchange between the fetus and mother occurs. Furthermore, maternal blood re-enters through the vein in the endometrium. The rate of uteroplacental blood flow rises during pregnancy, from the previous around 50 ml per minute at 10 weeks to 500 – 600 ml per minute at term.
There are several main functions of the placenta:
- As metabolic device
Especially during early pregnancy. The placenta produces glycogen, cholesterol, and fatty acids. They are the most nutrients and energy supplies for the fetus.
- As the transfer tool
There are 5 mechanisms of the substance through the placental membrane, namely:
- Simple diffusion
Simple diffusion depends on differences in levels, diffusion constants, and outside diffusion surfaces. Substances that pass through the placenta in this way are oxygen, carbon dioxide, and carbon monoxide. Some compounds or drugs with small molecules can also pass this way. Because of the large molecular heparin, it cannot cross the placenta.
- Accelerated or simplified diffusion
A real example is the transport of glucose from mother to fetus
- Active transport
Substances including in this transport are essential amino acids and water-soluble vitamins
Pinocytosis is a form of transport by entering substances intact
This occurs because of damage towards the villi so that the membrane of the placenta is torn. For example at the time of labor, at this time fetal blood cells can easily enter the maternal circulation
- Fetal blood circulation
Reoxygenated blood leaves the placenta through the umbilical vein, the umbilical vein runs inside the umbilical cord to the umbilicus. Then, there is a small vein that runs to porta hepatis. Almost no blood enters the liver because the umbilical veins directly connected with the vena cava inferior through a large vessel. This is called the ductus venosus, a structure that only exists in the fetal period. The mechanism after entering the inferior vena cava:
Blood goes up and reaches the right atrium. Most of the blood does not enter the right ventricle, not in the left atrium. Later it continues to a fetal hole which is only temporarily inside the interatrial septum, called the feramen ovale.
After reaching the left atrium, it enters through the mitral valve into the left ventricle. Contraction of the left ventricle pushes blood into the ascending aorta. Here, most of the blood is distributed to the heart, brain, and other limbs. Afterward, it enters into the thoracic aorta – descending abdominals. After circulating in the brain and other members of the body, blood returns to the heart through the superior vena cava and reach the right atrium. After flowing to the right atrium then the tricuspid hole, it enters the right ventricle. After that blood is pumped into the pulmonary artery.
The lungs in the fetus are inactive and receive only a little blood. Most of the blood in the pulmonary artery is channeled directly into the aorta through a large artery. It is called the dramatic duct and joins the aorta near the end of the aortic curve. Then it flows to aorta torasika. In the aorta, the blood is circulated to the viscera in the abdomen through the lower branches of the aorta. But in the fetus, most of the blood that reaches aortic bifurcation does not flow into the pelvic viscera and other limbs. In the placenta, an exchange occurs with the mother’s blood across the placenta.
The fetus makes its blood and as long as the complete placenta does not occur any mixing. After flowing through the capillaries – the capillary placenta, blood flows again to the fetus. Certain changes occur at birth. A lobe that is like a valve that keeps the foramen ovale closed and the right and left atrium are finally separated permanently. The ductus arteriosus constricts, disappears and has fibrosis. After the umbilical cord is cut and tied, the blood will stop flowing in the arteries, umbilical veins, and the ductus venosus. All structures are constricted and replaced by threads from fibrous tissue. The teres ligament from the liver is essentially a remnant of the umbilical vein.