Sci. y1 bio.3 (reproduction)

• Adolescence is a time period in which people go trough physical and emotial changes.
• The physical changes during adolescence is called puberty.
• Puberty takes place in between ages 9 - 14.

  Girls are most likely to start earlier than boys.
• Changes for both boys and girls are:

  -pubic and underarm hair grows

  -body smell gets stronger

  -emotional changes

  -growth spurt
• Changes for boys are:

  • voice gets deeper
  • testes and penis gets bigger
  • testes starts producing sperm
  • shoulders widen
  • facial hair growth
• Changes for girls are:

  • breast develops
  • overies start to release egg cells
  • periods start
  • hips widen
• Sex hormones cause all these changes in the body.

  They are chemical messengers, that travel through the body in the blood.
• The function of the male reproductive system is to produce sperm cells, and release them in the female reproductive system.
• testes


  produces sperm cells and male sex hormones
• glands


  produces nutrients that help sperm cells stay alive
• sperm ducts


  tubes that carry sperm from testes to penis
• urethra


  tube that carries sperm or urine out of the body
• penis


  thing that carries out urine and sperm out of the body
• The function of the female reproductive system is to produce egg cells, and then grow a baby for long enough for it to be born
• overies


  contain egg cells, on is released every month
• oviducts


  tubes that carry an egg cell to the uterus
• uterus


  this is where the baby develops until it is born
• cervix


  a ring of muscles at the enctrance of the uterus
• vagina


  receives sperm during sexual intercourse
• urtehra


  tube that carries urine from the bladder out of the body
• Gametes are reproductive cells.
• The male gamete is sperm and the woman gamete is an egg cell
• To create a new organism the nucleus of the sperm cell and the one of the egg cell join together
• An egg cell can't move by itself and gets moved by cilia.

  sperm cells can move and swim towards the egg cell
• during sexual intercourse semes is released into the woman.

  a males penis gets filled with blood and becomes erect.

  a womans vagina becomes moist.
• when a male releases semen in the womans vagina, this is called ejaculation
• a sperm cell swims from the vagina, to the uterus through the cervix, to the oviduct, to find an egg cell.
• when a sperm cell finds a egg cell, fertillisation can happen.
• a fertilised egg divides several times to form a ball of cells called an embryo.

  It attaches to the lining of the uterus and forms a fetus.

  this is called implantation.
• the time from fertilisation, until birth is called gestation.

  it takes about 9 months ( 40 weeks )
• after 8 weeks of growth an embryo is called a fetus.
• a fetus needs nutrients and oxygen during birth.

  it receives these from its mother, through her blood.
• in the uterus, there are 3 main structerus.

  • placenta, organ where substances pass between mothers and fetus blood
  • umbilical cord, connects fetus to the placenta
  • fluid sac, acts as a shock absorber and protects fetus from any bumbs
• 1 week, just a dot, cells start specializing

  4 weeks, 3mm, spine and brain forming, heart beating

  9 weeks, 3cm, tiny movement, lips and cheecks sense touch, eyes and ears forming

  12 weeks, 7cm, uses muscles to kick, suck, swallow and practise breathing
• during adoloscence girls will start period.

  once a month blood from the lining of the uterus leaves the body.

  this takes about 3 to 7 days
• the female reproductive system works in a sequence called, the menstrual cycle.

  this takes about 28 days.
• menstrual cycle:

  • day 1, blood leaves trough vagina
  • day 5, bleeding stops, lining uterus re-grows
  • day 14, new egg cell is released from ovaries, this is called ovaluation
• if a egg is fertilised, period stops until baby is born
• contraception is prevanting pregnancy by using for e.g. condoms or contraceptive pills
• a condom is a rubber layer that fits over an erect penis.

  it is called the " barrier " method, and prevents semen from being released into the woman