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Placenta

Placenta

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Author: Sophia Tutorial
Description:

This lesson will give an overview of the structure and function of the placenta in the development of an embryo as well as discuss other important membranes and structures associated with development.

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Tutorial

What's Covered

Welcome to this lesson on embryonic membranes. Today you are going to be learning about the various membranes that are associated with fetal development. Specifically, you will learn about:

  1. The Placenta
  2. The Amnion & Chorion
  3. The Allantois, Yolk Sac, & Cervix

1. The Placenta

The placenta provides nutrients and oxygen to an embryo or fetus and carries away waste through blood vessels. The placenta is the lifeline between the mother and the child, providing those nutrients and that oxygen that the child needs.

The placenta is connected to the umbilical cord and the umbilical cord attaches to the placenta to deliver nutrients and that oxygen and to carry away waste.The placenta and umbilical cord are very vascular structures which is important because that is how the mother is directly connected to the developing child.

Terms to Know

    • Placenta
    • The structure that develops from the outer cell layer of the blastocyst, the placenta provides blood flow, oxygen, and nutrients to the developing child while carrying away waste products.
    • Umbilical Cord
    • The cord that connects the embryo to the placenta, the umbilical cord carries nutrients to the child and wastes away.

2. The Amnion & Chorion

The amnion is the sac that encloses the embryo and is filled with amniotic fluid. This amnion provides insulation and protection for the developing fetus or embryo.

The next layer is the chorion, which is the outer membrane that provides protection and also secretes HCG, human chorionic gonadotropin. HCG prevents the breakdown of the endometrium during menstruation which is important because this prevents the child from being released from the mother's body.

Terms to Know

    • Amnion
    • A sac that encloses the embryo and is filled with amniotic fluid that cushions and protects the embryo.
    • Chorion
    • An outer membrane around the fetus that protects the fetus, absorbs blood from the mother to be transferred to the embryo, and secretes HCG to prevent endometrial breakdown.

3. The Allantois, Yolk Sac, & Cervix

The allantois is the part of the placenta that gives rise to blood vessels of the umbilical cord. The yolk sac is a membrane that produces early blood and germ cells along with parts of the embryo's digestive tube. It's not a membrane that stays around during the entire development and actually disintegrates quite early. Finally there is the cervix, which allows the baby to pass from the uterus into the vagina or birth canal.

Terms to Know

    • Allantois
    • A sac-like structure that gives rise to umbilical blood vessels.
    • Yolk Sac
    • A membranous sac attached to the embryo that provides early nourishment and develops the cardiovascular system and germ cells; the yolk sac eventually disintegrates.

Summary

This lesson has been an overview on various embryonic membranes, and their structure and function. Specifically, you learned about the placenta, amnion, chorion, allantois, yolk sac, and the cervix.

Keep up the learning and have a great day!

Source: THIS WORK IS ADAPTED FROM SOPHIA AUTHOR AMANDA SODERLIND

Terms to Know
Allantois

A sac-like structure that gives rise to umbilical blood vessels.

Amnion

A sac that encloses the embryo and is filled with amniotic fluid that cushions and protects the embryo.

Chorion

An outer membrane around the fetus that protects the fetus, absorbs blood from the mother to be transferred to the embryo, and secretes HCG to prevent endometrial breakdown.

Placenta

The structure that develops from the outer cell layer of the blastocyst, the placenta provides blood flow, oxygen, and nutrients to the developing child while carrying away waste products.

Umbilical Cord

The cord that connects the embryo to the placenta, the umbilical cord carries nutrients to the child and wastes away.

Yolk Sac

A membranous sac attached to the embryo that provides early nourishment and develops the cardiovascular system and germ cells; the yolk sac eventually disintegrates.