Question

State three functions of the placenta.

Answer 1

Hint: The placenta is an organ that provides a link between the mother and the child inside the womb. It is the characteristic feature of all mammals except marsupials and monotremes. It provides a large number of nutrients to the developing foetus for a long period of time before they are born.

Complete answer:
- The placenta is made up of tissue that is composed of both maternal tissue and embryo tissue.
- Foetal part develops from the chorionic sac
- Maternal part develops from the endometrium.
- It contains numerous finger-like projections called villi that help in the absorption.

The placenta is also called the transport system. The three functions of placenta are as follows:
> Gas exchange- when the foetus is inside the womb its lungs will not be able to take part in the gas exchange. Hence its function is carried out by the placenta. It plays a role in the exchange of oxygen and carbon dioxide between the mother and the foetus.

> Transfer of metabolites- the placenta is involved in the transport of glucose, amino acids, vitamins, etc.
- Glucose: foetus inside the womb cannot undergo gluconeogenesis. Hence the glucose is transferred from mother to the foetus.
- Amino acid: For the synthesis of proteins in the foetus it requires the amino acid, which is transferred through the placenta.
- Vitamins: Vitamins like B12, B6, biotin, and folate are transferred from mother to the foetus for its growth.

> Transfer of antibody IgG from the mother to the foetus helps to develop passive immunity to the foetus for a few months.

Note: Other functions of placenta are listed below:
- It acts as an endocrine gland where it secretes certain hormones like estrogen, relaxin, progesterone, gonadotropin etc.
- The waste material produced by the foetus moves to the mother through the placenta.
- It protects the attack of some toxic materials like histamine by acting as a barrier.