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प्रश्न
What is menstrual cycle? Describe it in brief.
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उत्तर
- The menstrual cycle is a series of cyclic changes that occur at intervals of about 28–30 days in a mature woman.
- It is controlled by pituitary hormones, namely FSH (Follicle Stimulating Hormone) and LH (Luteinizing Hormone), and ovarian hormones, estrogen and progesterone.
- Under the influence of FSH, the ovarian follicle containing the oocyte grows and matures.
- The growing follicle secretes estrogen.
- Estrogen stimulates the growth and regeneration of the inner lining of the uterus, called the endometrium.
- LH causes the mature follicle to burst and release the ovum. This process is called ovulation.
- After ovulation, the empty follicle is transformed into the corpus luteum, which secretes progesterone.
- Progesterone stimulates the endometrial glands to secrete nutrients and prepares the uterus for implantation of the fertilized ovum.
- If fertilization does not occur, the corpus luteum degenerates into the corpus albicans and stops secreting estrogen and progesterone.
- Due to the decrease in these hormones, the endometrium breaks down and is shed along with the unfertilized ovum through the vagina as menstrual flow, which lasts for about 3–5 days.
- If pregnancy does not occur, the menstrual cycle repeats regularly.
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संबंधित प्रश्न
Complete the following by filling in the blanks 1 to 5 with appropriate words:
The human female gonads are ovaries. A maturing egg in the ovary is present in a sac of cells called ______ (1). As the egg grows larger, the follicle enlarges and gets filled with a fluid and is now called the ______ (2) follicle. The process of releasing the egg from the ovary is called ______ (3). The ovum is picked up by the oviducal funnel and fertilization takes place in the ______ (4). In about a weak the blastocyst gets fixed in the endometrium of the uterus and this process is called ______ (5).
Define Amenorrhea
Draw a neat and well-labeled diagram showing T.S. of the ovary and describe the menstrual cycle in human females.
Describe the phases of the menstrual cycle and their hormonal control.
Read the following passage and answer the question that follows:
Rahini and her parents were watching a television programme. An advertisement flashed on the screen which was promoting the use of sanitary napkins. Rahini’s parents suddenly changed the channel, but she objected to her parents and explained the need and importance of such an advertisement.
What is first menstruation called? When does it occur?
The following is the illustration of the sequence of ovarian events (a-i) in a human female.
Name the ovarian hormone and the pituitary hormone that have caused the above-mentioned events.
In the absence of fertilization, corpus luteum ____________.
When does ovulatory phase occur?
Mainly which type of hormones control the menstrual cycle in human beings?
Withdrawal of which of the following hormones is the immediate cause of menstruation?
A biology student after studying the different levels of hormones during the menstrual cycle was comparing 2 subjects (Patients). A table was created after looking at the levels of hormones A and B for Subjects 1 and 2. Read the information in the table and answer the question that follows.
| HORMONE A | HORMONE B | |
| Subject 1 | Shows a peak on the 14th Day of the menstrual cycle. | Falls down during the luteal phase. |
| Subject 2 | Shows a peak on the 14th Day of the menstrual cycle. | The level is maintained high in the luteal phase. |
Which structure in the ovary will remain functional in subject 2?
Hormones responsible for menstrual cycle are produced from ______.
Menstruation is triggered by an abrupt decline in the amount of ______.
Given below is a flow chart showing ovarian changes during menstrual cycle. Fill in the spaces giving the name of the hormones responsible for the events shown.
What role does pituitary gonadotropins play during follicular and ovulatory phases of menstrual cycle? Explain the shifts in steroidal secretions.
Which of the following statement is correct?
Spermatogenesis is induced by ______.
Give a reason for the following:
The second half of the menstrual cycle is called the luteal phase as well as the secretory phase.
