menstrual cycle

• Puberty


  The period during which adolescents start to develop secondary sexual characteristics
• Secondary sexual characteristics


  • Facial hair in men
  • Breasts in women
• Reproductive hormones


  Hormones that trigger puberty, including testosterone in men and estrogen in women
• Testosterone is produced in the testes and stimulates sperm production
• Estrogen is produced by the ovaries
• Menstrual cycle


  1. Menstruation

  2. Uterus lining building up

  3. Ovulation

  4. Maintaining uterus lining
• Menstruation


  Period of bleeding due to breakdown of uterus lining
• Uterus lining building up

  Thick spongy layer with blood vessels to prepare for fertilized egg
• Ovulation


  Release of egg from ovary
• Maintaining uterus lining


  Progesterone maintains the lining of the uterus
• If no fertilized egg implants, the uterus lining breaks down and the cycle repeats
• If a fertilized egg implants, the menstrual cycle stops as the woman is pregnant
• Estrogen


  Produced in ovaries, stimulates uterus lining growth
• Progesterone


  Produced in ovaries, maintains uterus lining
• Luteinizing hormone (LH)


  Produced in pituitary gland, stimulates release of egg (ovulation)
• Follicle stimulating hormone (FSH)


  Produced in pituitary gland, stimulates egg maturation in ovaries
• FSH stimulates ovaries to produce estrogen


  As estrogen increases, it inhibits FSH (negative feedback)
• High estrogen levels


  Stimulate release of LH, causing ovulation
• Progesterone


  Inhibits both LH and FSH