P-2 Life Processes in Living Organisms Part – 2 — Science STD 10 — Question
Maharashtra BoardEnglish MediumSTD 10ScienceP-2 Life Processes in Living Organisms Part – 25 Marks
Question
What is menstrual cycle? Describe it in brief.
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Answer
Menstrual cycle is the events of cyclic changes that takes place with the interval of 28 to 30 days in mature woman.
Hormones from pituitary, FSH (Follicle Stimulating Hormone) and LH (Luteinizing Hormone) and hormones from ovary, estrogen and progesterone control the menstrual cycle.
Due to influence of FSH, the ovarian follicle grows along with the oocyte that is present in it.
This growing follicle produces estrogen.
Under the influence of estrogen, the uterine inner layer called endometrium grows or regenerates. In the meantime the development of follicle is completed.
LH from pituitary stimulates the bursting of ovarian follicle and releases the mature oocyte out of the follicle and the ovarian wall. This process is called ovulation.
The empty ovarian follicle after the ovulation becomes corpus luteum. Corpus luteum produces hormone progesterone.
Under the influence of progesterone, the glands from uterine endometrium start secreting. The oocyte if fertilized is implanted over this endometrium.
If oocyte is not fertilized, the corpus luteum becomes a degenerate body called corpus albicans. The corpus albicans cannot secrete estrogen and progesterone.
Due to lack of these hormones, the endometrial layer of the uterus collapses. The tissue debris, along with unfertilized egg is given out through the vagina as menstrual flow. This results in bleeding for about 5 days.
If woman is not pregnant, then this menstrual cycle keeps on repeating with regularity.
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