Placenta – Class 12 | Chapter – 3 | Biology Short Notes Series PDF

Placenta: The placenta is a temporary organ that connects your baby to your uterus during pregnancy. The placenta develops shortly after conception and attaches to the wall of your uterus. Baby is connected to the placenta by the umbilical cord. Together, the placenta and umbilical cord act as your baby’s lifeline while in the uterus.

• The placenta is a transient union of the fetal membrane and the material tissues.
• Through the umbilical cord, it provides nutritional support to the growing embryo.
• It includes blood arteries that link the placenta to the uterus and provide nourishment and O₂ supply to the developing embryo or baby.
• The placenta permits waste products such as urea, CO₂, and other waste materials to diffuse into the mother’s body for disposal.
• The placenta functions as an endocrine gland as well.
• It generates hormones such as estrogen and progesterone.

Formation of the Placenta

• The development of the placenta begins with the blastocyst’s implantation.
• The outer trophoblast cells and the inner cell mass are two separate differentiated embryonic cell types found in the 32-64 cell blastocyst.
• The placenta is made up of trophoblast cells.

Functions of the Placenta

• It provides nourishment to the developing foetus.
• It transfers oxygen, water and hormone from the mother to the developing foetus.
• It removes waste products from the blood of foetus.
• It provides protection to the foetus from microorganisms as they cannot pass through the placenta.
• It produces hormones which are necessary to maintain pregnancy, e.g. oestrogen, progesterone and relaxin.

Role of the placenta during pregnancy

The placenta passes oxygen, nutrients and antibodies from your blood to your baby. It also carries waste products from your baby back to your blood, so your body can get rid of them. The placenta also produces some hormones like oestrogen and progesterone that are needed during pregnancy.

Normal position of the placenta during pregnancy

The placenta should attach to the wall of the uterus, usually at the top, side, front or back. The exact location will vary from person to person and in each pregnancy.

The placenta can sometimes develop low in the uterus but will generally move higher as your uterus stretches. The position of the placenta will be checked at your 18-week ultrasound.

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By Team Learning Mantras