SOLUTION: Worksheet menstruation cycle questions - Studypool - Free Printable

WORKSHEET MENSTRUATION – Solutions and Explanations

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#### 1.1 Distinguish between ovulation and menstruation.
(4 marks)

| Ovulation | Menstruation |
|---------------|------------------|
| - It is the release of a mature ovum (egg) from the ovary into the fallopian tube. | - It is the shedding of the uterine lining (endometrium) along with blood through the vagina. |
| - Occurs around day 14 of a typical 28-day menstrual cycle. | - Occurs at the beginning of the menstrual cycle (day 1), marking the start of a new cycle. |
| - Triggered by a surge in luteinizing hormone (LH). | - Triggered by a drop in progesterone and estrogen levels when fertilization does not occur. |
| - Part of the ovarian cycle. | - Part of the uterine cycle. |

> ✔ Answer Summary: Ovulation is the release of an egg from the ovary, while menstruation is the shedding of the endometrial lining.

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#### 1.2 The following indicates the changes that occur in the ovaries and uterus during the menstrual cycle.

Let’s analyze the diagram step-by-step.

##### Key Interpretation of Diagram:
- Top graph: Hormone levels over time.
- Middle panel: Ovarian events (follicle development, ovulation, corpus luteum).
- Bottom graph: Uterine changes (endometrial thickening, breakdown).

From the graph:
- A = FSH (Follicle-Stimulating Hormone)
- B = LH (Luteinizing Hormone)
- C = Estrogen
- E = Progesterone
- D = Ovulation (peaks of LH and estrogen)
- F = Proliferative phase (follicular phase)
- G = Ovulation
- H = Secretory phase (luteal phase)

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#### 1.2.1 Describe the main events taking place in phases F, G, and H, and summarise the various important changes.
(6 marks)

- Phase F (Proliferative Phase / Follicular Phase):
- Occurs from the end of menstruation to ovulation (days 1–14).
- In the ovaries: Follicles develop under the influence of FSH; one dominant follicle matures and produces estrogen.
- In the uterus: Endometrium rebuilds and thickens after menstruation due to estrogen stimulation. Glands and blood vessels grow.
- This phase prepares the uterus for potential implantation.

- Phase G (Ovulation):
- Occurs around day 14.
- A surge in LH triggers the rupture of the mature follicle, releasing the ovum into the fallopian tube.
- The ruptured follicle becomes the corpus luteum.
- This is the most fertile period of the cycle.

- Phase H (Secretory Phase / Luteal Phase):
- Occurs from ovulation to the next menstruation (days 15–28).
- In the ovaries: Corpus luteum secretes progesterone and estrogen to maintain the endometrium.
- In the uterus: Endometrium becomes highly vascularized and glandular, ready for embryo implantation.
- If no fertilization occurs, the corpus luteum degenerates, leading to hormone drop and menstruation.

> ✔ Summary: F = rebuilding of endometrium; G = egg release; H = preparation of endometrium for pregnancy.

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#### 1.2.2 Identify the hormones A, B, C, and E which are secreted in the above phases and outline their most important functions.
(12 marks)

| Hormone | Name | Function |
|--------|------|---------|
| A | FSH (Follicle-Stimulating Hormone) | - Secreted by anterior pituitary. <br> - Stimulates development of ovarian follicles. <br> - Promotes estrogen production by follicles. |
| B | LH (Luteinizing Hormone) | - Secreted by anterior pituitary. <br> - Triggers ovulation. <br> - Stimulates formation of corpus luteum. |
| C | Estrogen | - Produced by developing ovarian follicles. <br> - Stimulates proliferation of endometrium. <br> - Causes cervical mucus to become thin and stretchy. <br> - Suppresses FSH but stimulates LH surge. |
| E | Progesterone | - Produced by corpus luteum. <br> - Maintains and thickens endometrium. <br> - Prepares uterus for implantation. <br> - Inhibits further ovulation. <br> - Reduces uterine contractions. |

> ✔ Each hormone gets 3 marks (name + 2 functions). Total: 12 marks.

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#### 1.2.3 Name the degenerating structure that is formed after phase G.
(2 marks)

- After phase G (ovulation), the ruptured follicle forms the corpus luteum.
- If fertilization does not occur, it degenerates into the corpus albicans.

✔ Answer: Corpus albicans

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#### 1.2.4 Describe what the endometrium is.
(4 marks)

- The endometrium is the inner lining of the uterus.
- It consists of glandular epithelium, connective tissue, and blood vessels.
- It undergoes cyclical changes during the menstrual cycle under the influence of estrogen and progesterone.
- Its primary function is to support the implantation of a fertilized egg and nourish the developing embryo.

✔ Answer: The endometrium is the mucosal lining of the uterus that thickens during the menstrual cycle to prepare for possible pregnancy.

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#### 1.2.5 What happens to the endometrium if fertilization does not occur?
(2 marks)

- If fertilization does not occur, the corpus luteum degenerates.
- This leads to a drop in progesterone and estrogen levels.
- Without these hormones, the endometrium breaks down and is shed through the vagina as menstrual flow.
- This marks the beginning of a new menstrual cycle.

✔ Answer: The endometrium is shed during menstruation.

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#### 1.2.6 What is the function of the endometrium if fertilization does occur?
(4 marks)

- The endometrium provides a nutritious environment for the implanted embryo.
- It supports implantation of the blastocyst.
- It develops into the placenta (along with trophoblast cells) to supply nutrients and oxygen to the fetus.
- It prevents maternal immune rejection of the embryo.
- It helps maintain pregnancy until birth.

✔ Answer: The endometrium supports implantation and nourishes the developing embryo; it contributes to forming the placenta.

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✔ Final Answers Summary:

| Question | Answer |
|--------|--------|
| 1.1 | Ovulation: release of egg from ovary. Menstruation: shedding of endometrium. |
| 1.2.1 | F: Endometrial regeneration; G: Ovulation; H: Endometrial secretion & maintenance. |
| 1.2.2 | A=FSH (follicle growth); B=LH (ovulation); C=Estrogen (endometrial growth); E=Progesterone (maintains endometrium). |
| 1.2.3 | Corpus albicans |
| 1.2.4 | Inner uterine lining that changes cyclically to support pregnancy. |
| 1.2.5 | Shed during menstruation. |
| 1.2.6 | Supports implantation and nourishment of embryo; forms part of placenta. |

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