Embryology and Fetal Circulation Review

These flashcards cover key concepts and stages in embryology and fetal circulation as outlined in the lecture notes.

What is the process by which a sperm and an ovum unite to form a zygote?

Fertilization.

How many chromosomes are present in a zygote?

46 chromosomes.

What is a morula?

A 16-32 celled mass surrounded by zona pellucida.

What does the blastocyst develop into during early embryonic development?

It has 100-150 cells and forms a fluid cyst.

What critical hormone is synthesized during implantation in week 2?

Human chorionic gonadotropin (HCG).

What is the purpose of HCG during pregnancy?

HCG helps maintain progesterone, which supports the pregnancy and uterine lining

What are the three primary germ layers developed during gastrulation?

Ectoderm, mesoderm, and endoderm.

What does the ectoderm develop into?

Skin, nervous system, and brain.

What structures does the mesoderm give rise to?

Muscles, bones, cartilage, circulatory system, and kidneys.

What does the endoderm become?

The lining of the digestive and respiratory tracts, liver, and pancreas.

When does the fetal heart begin development?

In the third week of gestation.

What is formed in the heart by the seventh week of gestation?

The heart will have four chambers.

What are the components of the embryonic heart tube?

Truncus arteriosus, bulbus cordis, primitive ventricle, primitive atrium, and sinus venosus.

What is the role of the internal septa during weeks 4-8?

To divide the primitive atrium and ventricle into left and right chambers.

What does the placenta provide to the fetus?

Oxygen and essential nutrients.

How many umbilical arteries and veins are typically present?

One vein and two arteries.

What is the route oxygenated blood takes from the placenta to the fetus?

Through the umbilical vein to the inferior vena cava (IVC).

What happens to the ductus arteriosus after birth?

It closes as pulmonary resistance drops.

What occurs when the first breath is taken by the newborn?

Lungs open, and pressure changes close the ductus venosus and ductus arteriosus.

Describe the function of the foramen ovale in fetal circulation.

Allows blood to flow from the right atrium to the left atrium.