Biology · Chemical Coordination and Integration · NEET
Because it exists only for a limited time. The placenta develops after the embryo attaches to the uterus and is expelled after the baby is born. Normal endocrine glands like the thyroid or pituitary stay for your whole life. Since the placenta appears only during pregnancy and then leaves the body, NCERT calls it a temporary endocrine gland.
NCERT lists five: human chorionic gonadotropin (hCG), human placental lactogen (hPL), estrogens, progestogens (progesterone group), and relaxin. In later pregnancy the placenta takes over from the corpus luteum in making the estrogen and progesterone that maintain the pregnancy.
It is endocrine. It releases its hormones directly into the mother's blood, not through a duct. Exocrine glands (like salivary or sweat glands) use ducts. Because the placenta has no duct and pours hormones into blood, it is an endocrine structure.
hCG (human chorionic gonadotropin) maintains the corpus luteum in early pregnancy so it keeps making progesterone, and it is the hormone detected by pregnancy tests. hPL (human placental lactogen) helps prepare the mother's body and breasts and adjusts her metabolism to supply the growing baby. Both come from the placenta but do different jobs.
Yes. Relaxin is secreted in the later phase of pregnancy. It relaxes the pelvic ligaments and softens the cervix to help during childbirth. NCERT names relaxin among the placental hormones, so keep it on your placenta list.
The corpus luteum is also temporary, but for NEET the placenta is the classic textbook example of a temporary endocrine gland during pregnancy. If a question asks for a temporary endocrine gland, placenta is the safest answer.
Match the following columns and select the correct option. Column-I: (a) Placenta (b) Zona pellucida (c) Bulbourethral Glands (d) Leydig cells Column-II: (i) Androgens (ii) Human Chorionic Gonadotropin (hCG) (iii) Layer of the ovum (iv) Lubrication of the penis
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Yes, it acts as a temporary endocrine gland during pregnancy because it secretes several hormones directly into the mother's blood.
After childbirth, when the placenta is expelled from the body. Its hormone secretion ends with delivery.
Human chorionic gonadotropin (hCG). Its presence in urine or blood confirms pregnancy.
Yes. In later stages of pregnancy the placenta produces the estrogens and progestogens needed to maintain pregnancy, taking over from the corpus luteum.
Relaxin is secreted by the placenta and the ovary during pregnancy. For NEET, remember it as a placental hormone that relaxes the pelvic region for childbirth.
