Human Reproduction

• Ovaries secrete the eggs, estrogen and progesterone
• Fertilisation occurs in the oviducts
• Female Anatomy :

  • Fallopian tube / oviducts
  • ovaries
  • cervix
  • uterus
  • endometrium
  • vagina
• Sperm are produced in the testes
• Scrotum holds the testes outside of the body (ideal temp - cooler environment for sperm production)
• Sperm duct : carries the sperm up and out of the testes during ejaculation
• Glands (Prostate and Seminal Vesicles) :

  • produce semen
  • semen contains energy, sugar (to use in respiration), alkali to protect sperm against the acidity of the female reproductive system
• Urethra :

  • urine
  • semen
• Journey of a #sperm :

  • produced in the testes
  • mix with the liquid in the glands to make semen
  • this is ejaculated into the vagina
  • swim through the cervix and into the uterus
  • they then swim up the fallopian tube
  • one sperm fertilises the egg
• The nuclei of the two cells (sperm and egg) fuse together to make a new cell. This is called the zygote.
• • The nuclei of the two cells fuse together to make a new cell.
  • This is called a zygote.
  • This develops into an embryo, then travels down to the uterus where it implants itself into the uterus lining / endometrium.
  • Placenta develops to provide oxygen and nutrients, whilst removing waste via the umbilical chord.
• Function of the Placenta :

  • Provides Oxygen and Nutrients to the embryo.
  • It removes waste (urea, carbon dioxide).
  • Secretes female hormones that maintain the pregnancy.
• Amniotic sac secretes amniotic fluid which protects the baby and helps it to develop
• Uterus = where the baby develops
• Menstrual Cycle :

  1. Menstruation : Bleeding, breakdown of uterus lining (4 days)
  2. Lining starts to build up : Prepares uterus lining for a fertilised egg (10 days)
  3. Ovulation : The egg is released from one of the ovaries ( takes 1 day)
  4. Maintaining the Lining of the Uterus: (takes 14 days). Towards the end of the cycle, if there is no fertilised egg, the uterus wall starts to break down. Back to stage 1.
• Oestrogen : Stimulates the uterus lining to grow. Increases at stage 2 (when the lining starts building up), and then falls when the lining has grown.
• Progesterone increases in stage four and maintains the lining of the uterus.

  If Progesterone levels drop, the uterus lining breaks down, and that is how the cycle restarts.
• LH and FSH are produced in the pituitary gland
• FSH : stimulates an egg to mature in one of the ovaries

  LH : stimulates the release of that egg on day 14 - ovulation
• FSH stimulates Ovaries to produce estrogen.

  Estrogen increases, FSH decreases.

  Estrogen increase stimulates LH.

  Progesterone inhibits LH and FSH