Menstruation happens due to these reasons: (select all that apply.)
A Lack of uterine hormones
B Presence of progesterone
C Presence of pituitary hormones
D Lack of embryo implanting in uterus
E Absence of progesterone
F Absence of ovarian hormones
The correct answer and explanation is :
Correct answers:
✅ A. Lack of uterine hormones
✅ D. Lack of embryo implanting in uterus
✅ E. Absence of progesterone
✅ F. Absence of ovarian hormones
Explanation (300 words):
Menstruation is the shedding of the uterine lining (endometrium) that occurs typically every month in females of reproductive age. It is part of the menstrual cycle, which is regulated by hormones produced by the ovaries, uterus, and pituitary gland. Menstruation happens primarily due to hormonal changes, particularly the decline of progesterone and estrogen levels—the two main ovarian hormones.
Option A: Lack of uterine hormones – Correct. Although the uterus itself doesn’t produce major hormones, this option refers to the drop in hormones (mainly estrogen and progesterone) that maintain the uterine lining. When these hormones decrease, the endometrium can no longer be sustained, leading to menstruation.
Option B: Presence of progesterone – Incorrect. Progesterone helps maintain the uterine lining after ovulation. Its presence supports early pregnancy. Menstruation occurs when progesterone levels fall.
Option C: Presence of pituitary hormones – Incorrect. Pituitary hormones like FSH and LH are crucial in regulating the menstrual cycle, but their presence does not cause menstruation directly. In fact, LH and FSH levels start to rise again after menstruation.
Option D: Lack of embryo implanting in uterus – Correct. If no embryo implants after ovulation, the body receives no signal (like hCG from a fertilized egg) to maintain progesterone levels. This leads to hormone withdrawal and menstruation.
Option E: Absence of progesterone – Correct. The drop in progesterone, due to the degeneration of the corpus luteum, is a key trigger for menstruation.
Option F: Absence of ovarian hormones – Correct. Estrogen and progesterone are ovarian hormones. Their withdrawal leads to the breakdown of the endometrial lining, resulting in menstrual bleeding.
In summary, menstruation is mainly due to the fall in ovarian hormones when no pregnancy occurs. This hormonal shift causes the uterine lining to shed.