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Questions
What is the menstrual cycle?
Briefly describe the menstrual cycle.
Solution 1
Female reproductive system undergoes some changes (that prepare the uterus for pregnancy) at puberty and those changes repeat at an interval of every 28-30 days. Such repetitive changes are called the menstrual cycle.
Solution 2
The beginning of the menstrual cycle marks the onset of puberty in human females. Menstruation occurs if an ovum released by the ovary of a woman is not fertilized during ovulation. This is described below.
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When a girl reaches puberty at the age of about 10, the sex hormones released into her blood cause some of the ova (or egg cells) in her ovaries to become mature (or ripe).
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Usually, one mature ovum (or egg) is released off (jm one of the ovaries into the oviduct once every 28 days. This is called ovulation.
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Before ovulation (or release of ovum), the inner wall of the uterus becomes thick and spongy, and full of tiny blood vessels to receive the fertilized ovum.
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If the ovum does not get fertilized then the thick and soft inner lining of the uterus breaks. So, the thick and soft inner lining of the uterus along with the blood vessels and the dead ovum comes out of the vagina in the form of bleeding called menstruation.
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Menstruation usually occurs 14 days after ovulation and usually lasts for about 3 to 5 days.
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After menstruation is over, the inner lining of the uterus starts building up again so that it may become ready to receive the next ovum.
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If the ovum does not get fertilized even now, then menstruation takes place again. This cycle of menstruation is repeated again and again in women after every 28 days. The menstrual cycle is controlled by hormones.
Menstruation stops temporarily when the ovum gets fertilized and the woman gets pregnant. Menstruation also stops due to nutritional deficiencies, low body weight, stress, eating disorders, excessive weight gain, etc.
RELATED QUESTIONS
Explain the menstrual phase in a human female. State the levels of ovarian and pituitary hormones during this phase.
Describe the roles of pituitary and ovarian hormones during the menstrual cycle in a human female.
Give appropriate biological or technical terms for the following:
The onset of menstruation in a young girl
Define: Menarche
Complete the following sentences with appropriate word:
The human gestation period is about ____________.
Explain the ovarian cycle with its different phases.
Why menstrual cycle does not take place before puberty and during pregnancy?
Painful menstruation is termed as ____________.
Identify the phase of the menstrual cycle during which there is a peak in the level of progesterone.
In humans, the menstrual cycle is generally of ______.
If the corpus luteum is present in the ovary even after 72 hours after ovulationit indicates that ______.
Match the Columns.
| Column I | Column II | ||
| i. | Proliferative phase | a. | Breakdown of the endometrial lining |
| ii. | Secretory phase | b. | Follicular phase |
| iii. | Menstruation | c. | Luteal phase |
In the absence of fertilization, corpus luteum ____________.
When does ovulatory phase occur?
____________ is transformed to corpus luteum during luteal phase of the menstrual cycle.
Corpus luteum produces ______.
Menstruation is triggered by a sudden decline in the amount of hormone secreted by corpus luteum. Identify the hormone.
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 ______
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. |
Subject 2 has a higher level of hormone B, which is ______
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:
When does the corpus luteum degenerate?
What role does pituitary gonadotropins play during follicular and ovulatory phases of menstrual cycle? Explain the shifts in steroidal secretions.
Spermatogenesis is induced by ______.
Write a short note on Proliferative Phase.
Given below is the diagram depicting the menstrual cycle in human beings. Study it carefully and answer the questions that follow.
- Which phases are indicated by ‘C’ and ‘D’?
- Name the structures labelled ‘F’. What is its role?
- Explain the changes in the level of progesterone during phases ‘C’ and ‘D’.
- Which hormone present in the urine confirms pregnancy in human beings?
- Identify the structure labelled ‘E’. Name the hormone released by it.
The egg is passed down through the oviduct by muscular contractions.
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.
