Block 1 Mini 1 Pt 2 Placenta Dr Kalli

During early pregnancy, the placental barrier is not fully developed, allowing substances to pass through easily. Simple diffusion is the process by which molecules move from an area of higher concentration to an area of lower concentration. Since drugs are small molecules, they can passively diffuse across the placental barrier without the need for any specific transport mechanism. Therefore, simple diffusion is the primary method by which most drugs are transported across the placenta during early pregnancy.

IgG is the correct answer because it is the only immunoglobulin that can cross the placental barrier. This allows the transfer of maternal antibodies to the fetus, providing passive immunity to the newborn. IgA, hormones from the pituitary gland, maternal cholesterol, and maternal phospholipids do not cross the placental barrier.

Human chorionic gonadotropin (hCG) is the hormone first produced by the syncytiotrophoblast cells of the early placenta to maintain the viability of the corpus luteum. This hormone is crucial in the early stages of pregnancy as it stimulates the production of progesterone by the corpus luteum. Progesterone is essential for maintaining the uterine lining and supporting the pregnancy. Therefore, hCG plays a vital role in ensuring the continued production of progesterone, which is necessary for the viability of the developing embryo.

The allantois gives rise to the umbilical arteries and vein. The allantois is a structure that develops during embryonic development and is responsible for waste disposal and gas exchange. It connects the developing embryo to the placenta and eventually forms the umbilical cord. The umbilical arteries carry deoxygenated blood from the fetus to the placenta, while the umbilical vein carries oxygenated blood from the placenta to the fetus. Therefore, the allantois is the correct answer as it is directly involved in the formation of the umbilical arteries and vein.

Lateral folding is the correct answer because ectopia cordis or Pentalogy of Cantrell is a congenital malformation of the anterior body wall that occurs during the process of lateral folding in embryological development. During lateral folding, the embryo's sides fold towards the midline, resulting in the formation of the body wall and the positioning of organs within the body cavity. In the case of ectopia cordis, the failure of proper lateral folding leads to the heart being positioned outside the chest.

Syncytiotrophoblast is the correct answer because it is a specialized layer of cells that form the outermost layer of the placenta. These cells play a crucial role in the production of placental estrogen, which is important for maintaining pregnancy and supporting fetal development. The syncytiotrophoblast cells have the ability to convert cholesterol into estrogen, and they also produce other hormones necessary for pregnancy.

During the final stages of fetal development, the placental barrier is composed of syncytiotrophoblast and endothelial cells of fetal capillaries. Syncytiotrophoblast is a layer of cells that forms the outermost layer of the placenta and plays a crucial role in nutrient and gas exchange between the mother and the fetus. Endothelial cells of fetal capillaries are responsible for transporting oxygen and nutrients from the mother's blood to the fetus, as well as removing waste products from the fetal circulation. Together, these two components form the barrier that allows for the exchange of substances between the maternal and fetal circulations.

Triglycerides do not cross the placental barrier because they are too large and cannot pass through the small pores of the placenta. The placenta selectively allows certain substances to pass through to the fetus, such as glucose, amino acids, and IgG antibodies, which are important for fetal development and immunity. Cortisol, a steroidal hormone, can also cross the placental barrier as it is necessary for fetal lung development. However, triglycerides, which are large fat molecules, are unable to pass through the placenta and therefore do not cross to the fetus.

During Stage 3 of labor, the placenta separates at the spongy layer of the decidua basalis from the uterus. This layer is located between the smooth chorion (chorion leave) and the decidua parietalis. It is at this layer that the placenta detaches from the uterine wall and is expelled from the body.

The aorta is the largest artery in the body and carries oxygenated blood from the heart to the rest of the body. In the case of a fetus, the aorta is responsible for supplying the most oxygenated blood to the developing baby. This is because the aorta directly connects to the placenta, which is responsible for exchanging oxygen and nutrients between the mother and the fetus. Therefore, the aorta plays a crucial role in ensuring that the fetus receives the necessary oxygen for growth and development.

The absence of a ventral double-fold of coelomic membrane connecting the heart to the ventral body wall (a ventral mesocardium) is a result of a bilateral connection of the early intraembryonic coelom rostral to the developing heart.

After the twentieth week of gestation, the placental membrane becomes thinned and consists of three layers. The correct answer states that the layers are syncytiotrophoblast, connective tissue of the villus, and fetal capillary endothelium. This arrangement is accurate because the syncytiotrophoblast is the outermost layer of the placental membrane, followed by the connective tissue of the villus, which provides support and structure. Finally, the fetal capillary endothelium is the innermost layer, responsible for the exchange of nutrients and waste products between the maternal and fetal blood.

The correct answer is that the woman should immediately have the surgery with no hormonal steroid supplements. This is because ovarian cancer is an aggressive form of cancer that requires prompt treatment. Delaying the surgery until after the birth of the child or until the third trimester of pregnancy could significantly increase the risk to both the mother and the baby. Additionally, hormonal steroid supplements are not necessary for the surgery and may not be safe for the woman or the developing fetus.