menstrual cycle

• The menstrual cycle occurs every month in females starting between 10 to 13 years old and continues for about 40 years
• The human ovaries can produce only one egg during a 28-day cycle
• The cycle is controlled by the follicle stimulating hormone produced in the anterior lobe of the pituitary gland
• If an ovum is not fertilized, the corpus luteum degenerates, progesterone production stops, and the inside membrane of the uterus breaks down, leading to menstruation
• The menstrual cycle can be summarized into stages:

  • Follicle stage: when one ovarian follicle grows to maturity
  • Ovulation stage: when a ripe follicle releases an egg
  • Corpus luteum stage: when the uterus prepares for the implantation of a fertilized egg
  • Menstrual flow stage: when the tissue lining of the uterus breaks down and is discharged
• Menstrual cramps are caused by strong contractions of the uterine wall before and during menstruation, often due to the excessive secretion of prostaglandins
• A feedback mechanism is a process where the level of a substance influences the level of another substance
• High levels of estrogen prevent more production of follicle stimulating hormone
• Estrogen stimulates the release of luteinizing hormone from the pituitary gland, which controls the production of progesterone
• High levels of progesterone can inhibit the further release of luteinizing hormone, demonstrating a negative feedback mechanism
• During labor and childbirth, a positive feedback mechanism occurs where contractions stimulate the release of oxytocin until the baby is born