Menstrual Cycle: Phases and Hormonal Control
The menstrual cycle is the cyclic change in ovary and uterus of a reproductive-age human female, involving menstruation, follicular development, ovulation and luteal phase under hormonal control.
In one line: FSH grows follicle, estrogen rebuilds lining, LH releases oocyte, progesterone preserves lining.
Concept Practice Coming SoonUnderstand it
- A typical menstrual cycle is about 28 days, though normal variation can occur.
- Menstruation marks shedding of the endometrial lining when pregnancy has not occurred.
- During the follicular phase, FSH supports follicular growth and estrogen helps rebuild the endometrium.
- A mid-cycle LH surge triggers ovulation, usually around day 14 in a 28-day cycle.
- After ovulation, the ruptured follicle forms the corpus luteum, which secretes progesterone and maintains the endometrium.
- If fertilisation and implantation do not occur, corpus luteum regresses, hormone levels fall and menstruation begins again.
- Exam questions often test phase-hormone-effect links.
Example
Rule to remember
Cycle rule: menstrual phase → follicular phase → ovulatory phase → luteal phase; falling ovarian hormones cause menstruation, while LH surge triggers ovulation.
See it worked out
Follow the example line by line, then use the same method on new questions.
Worked example
In an assertion-reason item, if assertion says LH surge causes ovulation and reason says corpus luteum secretes progesterone, both may be true but the reason does not directly explain the LH surge.
Method you can reuse
Visual tip
Useful diagram labels are days 1-5 menstruation, follicular growth, LH surge, ovulation, corpus luteum, progesterone rise and endometrial thickness. Notice that ovarian and uterine events are parallel.
Check yourself
Answer the question in your head before opening the answer.
Try it yourself
What causes menstruation if pregnancy does not occur?
Think first, then show answerHide answer
Common wrong answer
A common wrong answer is putting ovulation during menstruation. Ovulation is a mid-cycle event in a typical cycle, while menstruation begins the cycle.
Don't mix this up
Exam tip
Write it in the exam
Each point is worth about one mark. Write point 1 for a 1-mark question and keep adding points as the marks go up.
How CBSE asks it
Answer plan
- 1
Enough for 1 mark
The menstrual cycle is the cyclic change in ovary and uterus of a reproductive-age human female, involving menstruation, follicular development, ovulation and luteal phase under hormonal control.
- 2
Add for 2 marks
A typical menstrual cycle is about 28 days, though normal variation can occur.
- 3
Add for 3 marks
During the follicular phase, FSH supports follicular growth and estrogen helps rebuild the endometrium.
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