Menstrual cycle & contraception

1. Question 1

   Which hormone is primarily responsible for inhibiting the maturation of additional follicles during the later stages of the menstrual cycle?

   • A) Follicle Stimulating Hormone
   • B) Progesterone levels rising
   • C) Luteinising Hormone surge
   • D) Oestrogen secretion peak
   Show answer

   Answer: Progesterone levels rising

   Progesterone is secreted by the corpus luteum after ovulation. Its primary role is to maintain the uterus lining and provide negative feedback to the pituitary gland, which inhibits the secretion of FSH and LH, thereby preventing the development of further follicles.

2. Question 2

   What is the primary biological mechanism by which oral contraceptive pills prevent pregnancy?

   • A) Inhibiting all ovulation
   • B) Thickening cervical mucus
   • C) Killing sperm upon entry
   • D) Preventing implantation
   Show answer

   Answer: Inhibiting all ovulation

   Combined oral contraceptives contain oestrogen and progesterone, which mimic pregnancy signals. This inhibits the release of FSH from the pituitary gland, meaning no follicles mature and no egg is released, thus preventing fertilisation at the source.

3. Question 3

   Which structure in the ovary acts as the primary source of progesterone following the release of an egg?

   Show answer

   Answer: corpus luteum

   After ovulation, the remains of the ovarian follicle transform into a temporary endocrine structure called the corpus luteum. This structure secretes high levels of progesterone to prepare the endometrium for potential embryo implantation.

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