Human reproduction

• Sexual reproduction occurs when 2 gametes fuse to form a zygote
• A gamete is a sex cell
• Fertilisation is the point when the nuclei of gametes fuse to form a zygote
• A zygote is a cell formed from a result of fertilisation
• Male reproduction system

  • Testis- produce sperm
  • Scrotum-holds testes
  • Sperm duct- carries sperm from testes
  • Seminal vesicle- secrets fluid to nourish sperm
  • Prostate gland- secretes fluid to nourish sperm
• Puberty is a period of time when the sex organs of an individual mature and begin to function
• Male puberty

  • Production of sperm
  • Voice deepens
  • Growth of hair
• Female reproduction system

  • Ovary- produce eggs
  • Oviduct-carries eggs from ovaries
  • Uterus-holds the developing embryo & foetus
  • Cervix- opening from uterus to vagina
  • Vagina- holds penis during copulation , allows offspring to be born
• Female puberty

  • Ovaries begin to produce eggs
  • Menstrual cycle begins
  • Growth of hair
  • Breasts develop
• Menstrual cycle is a sequence of events that prepare the uterus to sustain an embryo
• Average 28 days

  • Day 1- uterine lining breaks down passes out of the body:period
  • Day 6- lining builds up again
  • Day 14- egg is released from the ovary:ovulation , lining remains in place for 14 days after ovulation. Then it breaks down and we go back to day 1.
• Menopause is when the menstrual cycle stops occuring
• Penetration occurs when the penis enters the vagina
• Ejaculation the release of sperm into the vagina near the cervix
• Pregnancy is when the embryo develops in a uterus. Lasts 38-40 weeks
• 5 days after fertilisation the embryo implants into the uterine lining
• Amniotic fluid allows the embryo to develop & acts as a shock absorber
• The placenta is an organ that allows substances to be exchanged between the mother's & embryo's blood.

  • O2 and food travel into the embryo's blood
  • CO2 and other waste leave the embryo's blood
• The umbilical cord allows rhe embryos blood to travel to the placenta and back again
• Contractions of the uterine muscle result in the baby being pushed out of the uterus
• Contraception means to prevent conception (implantation)
• Natural methods: identify the fertile period and avoid intercourse during this time
• Artificial method-

  block passage of sperm: condoms, diaphragms

  Prevent ovulation:the pill

  Prevent implantation: coil
• Surgical methods

  Vasectomy

  Tubal ligation
• Low fertility

  Men: low sperm count can be caused by poor lifestyle choices../ environmental pollution

  Female: failure to ovulate can be caused by stress/hormonal issues
• Medical techniques

  If treatment specific to the cause does not help a couple conceive the In Vitro Fertilisation (IVF) may be used
• Female

  1. Treated with hormones to boost egg production
  2. Eggs and sperm are harvested
  3. Eggs+sperm are mixed in a petri dish and incubated
  4. 2/3 developing embryos are placed into the uterus for normal development to occur