Menstrual Cycle

• What happens at the start of the Menstrual Cycle?

  FSH (Follicle Stimulating Hormone) is released from the anterior pituitary gland and into the blood.
• What does the increased FSH concentration stimulate?

  LH (Luteinising Hormone) production
• What is the function of FSH?

  It stimulates the maturation of one or more primary follicles.
• What does the production of oestrogen from the primary follicle inhibit?

  FSH / LH production, as only one egg is needed. This is negative feedback.
• What happens as the follicle grows?

  More oestrogen is produced so the concentration rises.
• What is the function of oestrogen?

  Causes the endometrium to thicken.
• What happens at high concentrations of oestrogen?

  LH production is stimulated. As the LH concentration rises, FSH production is stimulated.
• What is the function of LH?

  LH stimulates ovulation and the production of testosterone in males.
• What does LH stimulate the Gradian Follicle to become after 14 days?

  The Corpus Luteum.
• What does the Corpus Luteum make?

  Progesterone and Oestrogen, causing their concentrations to rise.
• What are the functions of Oestrogen and Progesterone?

  They maintain the lining of the uterus (endometrium) and inhibit FSH / LH production.
• What happens if the cycle is not fertilised?

  The Corpus Luteum shrinks, progesterone and oestrogen production falls and the lining of the uterus breaks down.
• What happens if the cycle is fertilised?

  hCG (human chorionic gonadotrophin) is made, which maintains and grows the Corpus Luteum, which prevents menstruation.
• What are the 2 phases in the Menstrual Cycle?

  Follicular phase and Luteal phase.
• Menstrual Hormone Graph


  Shows the concentration of each hormone and the timeline of follicle growth.