Reproduction in humans
Read the following passage carefully and answer the given questions.
The female reproductive system consists of a pair of ovaries, a pair of oviducts, a uterus, a vagina, external genitalia, and a pair of mammary glands. The ovaries produce the female gamete and some steroidal hormones. Ovarian follicles in different stages of development are embedded in the stroma. The oviducts, uterus and vagina are female accessory ducts. The uterus has three layers, namely perimetrium, myometrium and endometrium. The female external genitalia includes mons pubis, labia majora, labia minora, hymen and clitoris. The mammary glands are one of the female secondary sexual characteristics. Spermatogenesis results in the formation of sperm that is transported by the male sex accessory ducts. A normal human sperm is composed of a head, neck, a middle piece and tail. The process of formation of mature female gametes is called oogenesis. The reproductive cycle of female primates is called the menstrual cycle. The menstrual cycle starts only after attaining sexual maturation. During ovulation, only one ovum is released per menstrual cycle. The cyclical changes in the ovary and the uterus during the menstrual cycle are induced by changes in the levels of pituitary and ovarian hormones.
Which one of the following hormones is not produced during parturition?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → LH
Parturition is the delivery of the foetus at the end of pregnancy. It is induced by a neuroendocrine mechanism. The foetus and the placenta send signals that cause mild contractions of the uterus. These release oxytocin from the mother’s pituitary, and oxytocin makes the contractions stronger.
(1) Cortisol — Produced during parturition. It is one of the three hormones that the book names for this mechanism.
(2) Oxytocin — Produced during parturition. It acts on the muscle of the uterus and gives strong contractions. The contractions in turn bring out more oxytocin, and this goes on until the baby is delivered.
(3) LH — Not produced during parturition. LH is a gonadotropin of the pituitary. It acts in the menstrual cycle: its surge in mid-cycle makes the Graafian follicle burst and release the ovum. It has no part in childbirth.
(4) Estrogens — Produced during parturition. They are the third hormone named for this mechanism.
Note: The passage is taken from NCERT. NTA has put lines of the NCERT text together to make it. Most CUET (UG) questions come straight from NCERT, so study the book line by line, including figures and their titles.
NCERT Extract:
Parturition and Lactation – “… Parturition is induced by a complex neuroendocrine mechanism. The signals for parturition originate from the fully developed foetus and the placenta which induce mild uterine contractions called foetal ejection reflex. This triggers release of oxytocin from the maternal pituitary. Oxytocin acts on the uterine muscle and causes stronger uterine contractions, which in turn stimulates further secretion of oxytocin.”
Summary – “… The process of childbirth is called parturition which is induced by a complex neuroendocrine mechanism involving cortisol, estrogens and oxytocin.”