What is placenta? Describe its structure. State its functions in case of a pregnant human female.

Placenta

The placenta is a specialized, temporary physiological organ (a disc-like tissue) that connects the developing embryo to the uterine wall of the mother. It serves as the structural and functional interface between the maternal body and the fetus during pregnancy.

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Structure of the Placenta

1. Disc-like Shape: It is a flat, disc-shaped structure embedded deeply within the uterine wall of the mother.
2. Embryonic Side (Villi): On the side facing the embryo, the placenta contains numerous finger-like projections called villi.
3. Maternal Side (Blood Spaces): On the mother's side, there are large blood spaces that surround and bathe these villi.
4. Surface Area: This specific arrangement provides a massive surface area for the exchange of nutrients, gases, and metabolic waste products between the mother and the embryo.

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Functions of the Placenta in a Pregnant Female

1. Nutrition: It facilitates the transfer of essential nutrients (such as glucose, amino acids, vitamins, and minerals) from the mother's blood to the developing embryo to support its growth.
2. Respiration: It allows oxygen ($O_2$) to diffuse from the maternal blood into the fetal blood, and carbon dioxide ($CO_2$) produced by the embryo to diffuse back into the mother's blood for elimination.
3. Excretion: The metabolic waste products (like urea) generated by the developing embryo are transferred across the placenta into the mother's blood, which are then excreted by the mother's kidneys.
4. Endocrine Function: It secretes crucial hormones (such as progesterone and estrogen) necessary for maintaining the pregnancy and supporting fetal development.