Human Development: Placenta and Twins

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Questions and Answers

What is the primary function of the placenta?

Hormonal regulation

Fetal immunity

Nutrient and gas exchange between mother and fetus (correct)

Waste storage

Which two components make up the placenta?

Chorion and decidua

Fetal tissue and maternal blood

Maternal and fetal parts (correct)

Uterine wall and amniotic fluid

From which layer of the uterus does the maternal part of the placenta develop?

Endometrium (correct)

Placental layer

Perimetrium

Myometrium

What develops the fetal part of the placenta?

Chorionic sac Signup and view all the answers

Which of the following is NOT a function attributed to the placenta?

Direct fetal circulation Signup and view all the answers

What results from the division of the embryonic disc in monozygotic twins?

Two embryos within one amniotic sac Signup and view all the answers

What structures are present in a case of monozygotic twins that do not have complete division?

One amnion, one chorion, and one placenta Signup and view all the answers

What is a characteristic of the embryonic disc in the development of monozygotic twins?

It partially splits, leading to shared structures Signup and view all the answers

In which situation is it likely that monozygotic twins share the same amniotic sac?

Incomplete division of the embryonic disc Signup and view all the answers

Which statement accurately describes the condition of amnion, chorion, and placenta in monozygotic twins resulting from incomplete division?

They share one amnion, chorion, and placenta Signup and view all the answers

What is the primary function of the placenta in relation to the fetus?

To transport nutrients and oxygen from the maternal blood to the fetal blood Signup and view all the answers

What substances are primarily transported from the fetal blood back to the maternal blood?

Waste materials and carbon dioxide Signup and view all the answers

In what way does the placental membrane differ in its function throughout pregnancy?

Its thickness and permeability remain consistent throughout all stages Signup and view all the answers

How do nutrients primarily pass from the maternal blood to the fetal blood?

Via diffusion across the placental barrier Signup and view all the answers

Which of the following best describes the role of the umbilical cord during pregnancy?

It acts as a conduit for blood between the fetus and placenta Signup and view all the answers

What maintains the circulation of amniotic fluid to and from the fetus?

The balance of osmotic pressure and fetal movements Signup and view all the answers

What term is synonymous with conjoint twins?

Siamese twins Signup and view all the answers

Which statement accurately describes the nature of conjoint twins?

They are joined together at birth. Signup and view all the answers

What does the term 'conjoint' specifically refer to in the context of twins?

Joined together Signup and view all the answers

In what way do conjoint twins differ from traditional twins?

Conjoint twins are physically attached. Signup and view all the answers

What is a common misconception about conjoint twins?

They cannot live past infancy. Signup and view all the answers

Which condition is NOT typically associated with conjoint twins?

Having two separate circulatory systems Signup and view all the answers

Which terminology describes the phenomenon of twins being joined together?

Conjoint Signup and view all the answers

How are conjoint twins primarily formed?

From a single fertilized egg that did not fully split Signup and view all the answers

What is one example of a health concern specifically impacting conjoint twins?

Higher likelihood of heart defects Signup and view all the answers

Which factor does NOT define the classification of conjoint twins?

Genetic similarity Signup and view all the answers

What are the layers involved in nutrient exchange within the placental villi?

Cytotrophoblast and syncytiotrophoblast Signup and view all the answers

What is primarily responsible for the transport of waste products from the fetus to the mother via the placenta?

Fetal blood vessels Signup and view all the answers

Which of the following best describes the maternal part of the placenta?

It is derived from the endometrium. Signup and view all the answers

How does the transport of nutrients from maternal blood to fetal blood occur in the placenta?

Via specific transport proteins in the placental membranes Signup and view all the answers

Which structure plays a critical role in the functioning of the placenta as a transport system?

Chorionic villi Signup and view all the answers

Study Notes

Placenta

Primary site of nutrient and gas exchange between mother and fetus.
Fetomaternal organ that has two components:
- Fetal part from the chorionic sac
- Maternal part from the endometrium
The placenta and umbilical cord function as a transport system for substances passing between the mother and the fetus.
- Nutrients and oxygen pass from maternal blood through the placenta to the fetal blood.
- Waste materials and carbon dioxide pass from fetal blood through the placenta to the maternal blood.

Conjoint Twins

Also known as Siamese twins.
Occur when the embryonic disc does not completely split or divide.
One amnion, one chorion, and one placenta.

Monozygotic Twins

Division of the embryonic disc results in two embryos within one amniotic sac.
Twin transfusion syndrome can occur when there is anastomosis of the placental vessels.
- One twin may receive most of the nutrition from the placenta.
- This can lead to anemia in the donor twin and congestive heart failure in the recipient twin.
Approximately 65% of monozygotic twins are formed from one zygote by division of the inner cell mass.

Placenta Function

The placenta is a vital organ for fetal development.
It serves as the primary site for nutrient and gas exchange between the mother and the fetus.
The placenta facilitates the transport of nutrients and oxygen from the maternal blood to the fetal blood.
Waste materials and carbon dioxide are transported from the fetal blood to the maternal blood through the placenta.

Placenta Structure

The placenta is a fetomaternal organ, meaning it has both fetal and maternal components.
The fetal part develops from the chorionic sac.
The maternal part originates from the endometrium, the inner lining of the uterine wall.

Placental Villi

The placental villi are intricate structures responsible for the exchange of nutrients and waste products.
Maternal blood pools within spaces called lacunas, which are surrounded by layers of cells.
These layers include the cytotrophoblast and the syncytiotrophoblast.
Fetal blood vessels within the villi access the maternal blood supply for nutrient uptake and waste removal.

Amniotic Fluid Circulation

Amniotic fluid is continuously circulated and exchanged between the fetus and the surrounding environment.
The fetus swallows amniotic fluid, which is then returned to the amniotic sac.

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Description

Explore the critical roles of the placenta in nutrient and gas exchange between mother and fetus. Delve into the complexities of twin types, including conjoint and monozygotic twins, and their developmental implications. This quiz covers key facts and functions essential for understanding human prenatal development.