State any three functions of placenta in human female.

Explanation

In mammals, placenta performs the following functions :
(i) It helps in the nutrition of embryo as the nutrients like amino acids, mono-sugars, vitamins etc., diffuse from maternal blood into foetal blood through placenta.
(ii) It helps in respiration of the embryo as `O_(2)` of the maternal blood and `CO_(2)` of foetal blood diffuse through placenta.
(iii) It also helps in excretion of the nitrogenous wastes of foetal blood like urea which diffuse into maternal blood through placenta.
(iv) It also acts as an endocrine gland as it secretes certain hormones like estrogen, relaxin, progesterone and Human Chorionic Gonadotropin (HCG).
(v) It stores the glycogen till the formation of liver. Also stores fats and iron.
(vi) It also acts as an effective barrier for certain toxic chemicals like histamine.
(vii) Helps in the transport of antibodies from maternal blood to the foetus.
(viii) Helps in the transport of drugs, pathogens like viruses for syphilis, chicken pox etc.