Photo AI
Describe hormonal control of the menstrual cycle under the following headings: (i) events leading to ovulation; (ii) events following ovulation. - Scottish Highers Human Biology - Question 14 - 2015
Question 14
Describe hormonal control of the menstrual cycle under the following headings: (i) events leading to ovulation; (ii) events following ovulation.
Worked Solution & Example Answer:Describe hormonal control of the menstrual cycle under the following headings: (i) events leading to ovulation; (ii) events following ovulation. - Scottish Highers Human Biology - Question 14 - 2015
Step 1
events leading to ovulation
Answer
- The menstrual cycle begins with the release of Gonadotropin-releasing hormone (GnRH) from the hypothalamus.
- This hormone stimulates the pituitary gland to secrete Follicle Stimulating Hormone (FSH).
- FSH promotes the growth and maturation of ovarian follicles.
- As the follicles mature, they produce increasing amounts of oestrogen.
- Oestrogen influences several key processes:
- Stimulates the thickening of the endometrium (uterine lining).
- Triggers the surge in Luteinizing Hormone (LH) by the pituitary gland, leading to ovulation.
- This rising level of oestrogen provides negative feedback to inhibit further FSH production.
Step 2
events following ovulation
Answer
- After ovulation, the ruptured follicle transforms into the corpus luteum.
- The corpus luteum secretes progesterone and some oestrogen, which are crucial for maintaining the endometrial lining.
- Progesterone helps stabilize the endometrium and prepares it for potential implantation of an embryo.
- If fertilization does not occur, the corpus luteum degenerates, leading to a drop in progesterone and oestrogen levels.
- This decrease results in the shedding of the endometrial lining, marking the onset of menstruation.