Placenta and Embryo Development Online Quiz

Small for Gestational Age (SGA) is clinically defined as an infant with a birth weight below the 10th percentile; severe SGA is defined as below the 3rd percentile.

SGA is defined as being below the 10th percentile, not above it. Therefore, the statement that a SGA baby is above the 10th percentile is false.

SGA stands for Small for Gestational Age, which describes a fetus or infant that is smaller than expected for the number of weeks of pregnancy.

Fetal movement perception can be influenced by a variety of factors including the health of the fetus, maternal smoking, the position of the fetus, and the position of the placenta.

An anterior placenta is located on the front wall of the uterus, which can act as a cushion and make it more difficult for the mother to feel fetal movements compared to a posterior placenta.

Fetal breathing movements are a sign of fetal well-being and can typically be detected via ultrasound starting around 10 weeks of gestation.

While the fetus grows throughout pregnancy, the most significant weight gain occurs during the third trimester as the fetus prepares for birth.

Amniotic fluid is slightly alkaline, with a pH typically ranging between 7.0 and 7.5.

Amniotic fluid is composed primarily of water (about 98-99%), along with electrolytes, proteins, carbohydrates, and fetal cells.

The umbilical cord normally contains two umbilical arteries, which carry deoxygenated blood from the fetus to the placenta, and one umbilical vein, which carries oxygenated blood from the placenta to the fetus.

The umbilical cord does not contain nerves, which is why cutting the cord after birth is painless for both the mother and the newborn.

Wharton's Jelly is the gelatinous substance that surrounds and protects the blood vessels within the umbilical cord, preventing them from kinking or compressing.

The trophoblast is crucial in forming the placenta and acts as an immunological barrier, preventing the mother's immune system from attacking the fetus.

The placenta takes over the production of progesterone and oestrogen from the corpus luteum around the end of the first trimester, typically by the third month.

The placenta facilitates the exchange of materials between mother and fetus. While oxygen and nutrients move toward the fetus, metabolic waste products move from the fetus to the mother for excretion.

Passive immunity occurs when antibodies are transferred from one individual to another, such as from mother to fetus across the placenta. Active immunity requires the individual to produce their own antibodies through exposure to an antigen.

In human prenatal development, the embryonic stage lasts through the end of the eighth week following fertilization. Beginning at the ninth week, or the end of the eighth week, the developing organism is officially classified as a fetus.

Amniotic fluid production begins early in development, typically around the 4th to 5th week of gestation, initially produced by the amniotic membrane.

The syncytiotrophoblast cells of the placenta are responsible for the production of Human Chorionic Gonadotropin (HCG) to maintain the corpus luteum during early pregnancy.

The ectoderm is the outermost germ layer and gives rise to the epidermis (skin), the nervous system, and sensory organs like the eyes and ears. Mesoderm forms muscles and bones, while endoderm forms internal organs like the lungs and intestines.

The inner cell mass (embryoblast) of the blastocyst is responsible for forming the embryo itself and associated structures like the yolk sac and amnion, while the outer trophoblast forms the placenta.

After ovulation, the human oocyte is viable for fertilization for a relatively short window, typically estimated between 12 and 24 hours.