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Describe the menstrual cycle in human females and add a note on its hormonal control.

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Last updated date: 23rd Jun 2024
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Answer
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Hint: A woman's body goes through a number of changes per month during the years between puberty and menopause to get it ready for a potential pregnancy. The menstrual cycle is what this sequence of hormone- driven events is called.

Complete answer:
An egg forms and is released from the ovaries during each menstrual cycle. The uterine lining builds up. The uterine lining disappears during a menstrual period if a pregnancy does not occur. Then the loop begins again.
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The menstrual cycle of a woman is split into four phases:
- Menstrual phase
- Follicular phase
- Ovulation phase
- Luteal phase
The first stage of the menstrual cycle is the menstrual phase. It's also when you get your period.
This process begins when an egg from the previous cycle isn't fertilized. Since conception hasn't taken place, levels of the hormones oestrogen and progesterone drop. The uterine wall is shredded.
- The follicular phase starts on the first day of your period and ends when ovulation occurs.
It starts when the hypothalamus sends a signal to the pituitary gland to release follicle- stimulating hormone (FSH). This hormone stimulates the ovaries to develop about 5 to 20 tiny sacs called follicles. Each follicle contains an egg that is immature.
- For around 16 days, the average follicular period lasts. Depending upon your cycle, it can range from 11 to 27 days.
- Ovulation phase: During the follicular process, increasing oestrogen levels cause the pituitary gland to release luteinizing hormone (LH). This is what initiates the ovulation process.
Ovulation is when a mature egg is produced by an ovary. To be fertilized by sperm, the egg moves down the fallopian tube into the uterus.
- If you have a 28 - day period, ovulation occurs around day 14, right in the middle of the menstrual cycle.
- It lasts approximately 24 - 36 hours. The egg will die or dissolve after a day if it is not fertilized.
- Luteal phase: Corpus luteum is formed after the follicle releases its egg. Hormones are released by this structure, primarily progesterone, and some oestrogen. The increase in hormones makes the uterine lining thick and ready for the implantation of a fertilized egg.
- For 11 to 17 days, the luteal period lasts. The period is 14 days on average.

Note:
- Negative feedback on pulse release of gonadotropin- releasing hormone (GnRH) and luteinizing hormone (LH) is triggered by breastfeeding.
- Breastfeeding women can experience complete suppression of follicular development depending on the frequency of the negative feedback.