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
• The average length of a menstrual cycle is around 28 days but varies between people
• Menstruation


  The period of bleeding that normally lasts about 4 days and is due to the breakdown of the uterus lining
• Uterus lining building up

  Lasts around 10 days up to day 14, preparing the uterus lining for a fertilized egg
• Ovulation


  The release of an egg from one of the ovaries, occurring on a single day
• Maintaining uterus lining


  Stretches from day 14 to day 28, maintaining the uterus lining if no fertilized egg has implanted
• If a fertilized egg implants, the menstrual cycle stops as the woman becomes pregnant
• Estrogen


  Produced in the ovaries, stimulates the growth of the uterus lining
• Progesterone


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


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


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


  As estrogen levels increase, they start to inhibit FSH (negative feedback)
• High estrogen levels


  Stimulate the release of LH, causing ovulation
• Progesterone


  Inhibits both LH and FSH
• 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
• Reproductive hormones


  • Testosterone
  • Estrogen
• Menstrual cycle


  The cyclical changes in the uterus lining and hormone levels that occur in women of reproductive age
• Stages of the menstrual cycle

  1. Menstruation

  2. Uterus lining builds up

  3. Ovulation

  4. Maintaining uterus lining
• Menstruation


  The period of bleeding that normally lasts about 4 days and is due to the breakdown of the uterus lining
• Uterus lining build-up


  The uterus lining becomes a thick spongy layer with lots of blood vessels, preparing for a fertilized egg
• Ovulation


  The release of an egg from one of the ovaries
• Maintaining uterus lining


  The uterus lining is maintained if no fertilized egg implants, otherwise the cycle stops due to pregnancy
• Reproductive hormones involved in the menstrual cycle

  • Estrogen
  • Progesterone
  • Luteinizing hormone (LH)
  • Follicle stimulating hormone (FSH)
• Estrogen


  Produced in the ovaries, stimulates the uterus lining to grow
• Progesterone


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


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


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


  Estrogen levels start to increase
• Increasing estrogen levels


  Start to inhibit FSH (negative feedback)
• High estrogen levels


  Stimulate the release of LH, causing ovulation
• Progesterone


  Inhibits both LH and FSH