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प्रश्न
Describe the changes that occur in ovaries and uterus in human female during the reproductive cycle.
उत्तर
Menstrual cycle is the reproductive cycle in all primates and begins at puberty (menarche).
In human females, menstruation occurs once in 28 to 29 days. The cycle of events starting from one menstruation till the next one is called the menstrual cycle. These changes are brought about by ovarian and pituitary hormones.
The changes occurring in the ovaries are as follows:
- The cycle starts with the menstrual phase, where menstruation occurs. This is followed by the follicular phase. In this phase, the primary follicles mature into the Graffian follicles and the release of gonadotropins (LH and FSH) also increases. This causes follicular growth and the growing follicles produce oestrogen.
- The LH and FSH are at their peak in the middle of the cycle (14th day), and cause the rupture of the Graffian follicles to release ovum. This phase is called the ovulatory phase.
- The remains of the Graffian follicles get converted into the corpus luteum that secretes progesterone for the maintenance of the endometrium.
- In the absence of fertilisation, the corpus luteum degenerates, thereby causing the disintegration of the endometrium and the start of a new cycle.
The changes occurring in the uterus are as follows:
- In the absence of fertilisation, during the menstruation phase, the endometrium of the uterus breaks down. Blood vessels in liquid state are discharged.
- During the follicular phase, the action of the gonadotrophins (LH and FSH) causes the regeneration of the endometrium to receive the fertilised egg.
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संबंधित प्रश्न
Observe the figure and answer the questions given below.
a) What does the above figure indicate?
b) Which human organs are involved in this process?
c) Name the hormones responsible for this process.
d) After how many days these repetitive changes take place?
e) ‚A woman should stay away from others, as her body is impure during this process.‛ What is your opinion about this statement? Elaborate it.
Explain the role of hormones during the menstrual cycle.
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?
Calculate the number of spermatozoa produced by a single primary spermatocyte.
Which hormone is secreted by the developing secondary follicles?
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 of the following statements is true about the subjects?
Distinguish between pollination and fertilisation. Mention the site and product of fertilisation in a flower.
Draw a neat, labelled diagram of a pistil showing pollen tube growth and its entry into the ovule.
Exit from the cell cycle and remain dormant for long time by a cell is represented by one of the following phases of the cell cycle:
The secretory phase in the human menstrual cycle is also called:
Given below is a group of terms. In the group, one pair indicates the relationship between the two terms. Rewrite and complete the second pair on a similar basis.
Follicular phase: 5-12 days:: Luteal phase : ______ days.
