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प्रश्न
Explain menstrual cycle in human females.
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उत्तर
A 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. Menstrual phase refers to the beginning of menstruation wherein the endometrium along with its rich blood supply is shed (menses). During this phase, the levels of both the ovarian and the pituitary hormones are low. The level of follicle stimulating hormone (FSH) starts to increase during the later stages of this phase.
2) The menstrual phase is followed by the follicular phase wherein the primary follicles mature into the Graffian follicle under the influence of FSH and LH. The developing follicles release oestrogen which causes the regeneration of the endometrium. Since the follicles and the endometrium proliferate during the follicular phase, it is also known as the proliferative phase.
3) At the time of ovulation, the release of gonadotropins (LH and FSH) increases. The LH and FSH are at their peak in the middle of the cycle (14thday) and cause the rupture of the Graafian follicle to release the ovum (ovulation). The remains of the Graafian follicle get converted into corpus luteum, which secretes progesterone for the maintenance of the endometrium in case of pregnancy.
4) In absence of pregnancy, corpus luteum degenerates which causes disintegration of the endometrium leading to mensuration and marking a new cycle.
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संबंधित प्रश्न
Explain the menstrual phase in a human female. State the levels of ovarian and pituitary hormones during this phase.
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).
Explain the ovarian and uterine events that occur during a menstrual cycle in a human female under the influence of pituitary and ovarian hormones respectively.
Give Reasons
The chances of pregnancy to occur are most favourable on or about the 14th day of the menstrual cycle. Explain.
When does the following step take place?
Identify the INCORRECT statement.
To answer the question, study the graphs below for Subjects 1 and 2 showing different levels of certain hormones.
The peak observed in Subject 1 and 2 is due to ______
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. |
The peak observed in Subject 1 and 2 is due to ______
The figure show a section of human ovary. Select the option which gives the correct identification of either A or B with function/characteristic.
The onset of menstruation in women is called ______.
