Chapter 14: Sexual Reproduction

• Male gamete


  sperm
• Female gamete


  Egg
• Zygote


  Fusion between nucleus of sperm and egg
• dissimilar


  not similar
• Sexual reproduction


  a process involving the fusion of the nuclei of two gametes (sex cells) to form a zygote and the production of offspring that are genetically different from each other
• Testis


  Produces sperm and male sex hormones
• Scrotum


  Lower temperature essential for sperm to develop properly
• Sperm duct


  Transports sperm from testis to urethra
• Prostate gland


  Secretes fluid that contains nutrients and enzymes that nourishes sperm and stimulate sperms to actively swim
• Semen


  Sperm and fluid
• Urethra


  Where semen and urine passes out of the body through
• Penis


  Erectile organ that enters the vagina during sexual intercourse to deposit semen, containing sperm
• Ovaries


  -Produces & releases mature egg

  -produce female sex hormones, oestrogen & progesterone
• Oviduct


  -Move mature egg from the ovary to the uterus through sweeping motion of cilia and peristalsis

  -site where fertilisation takes place
• Uterus


  -site where the foetus develops during pregnancy

  -lined with the uterine lining
• Uterine lining


  Site where the embryo is implanted
• Cervix


  -opening allows menstrual blood flow out into the vagina during menstruation

  -dilates during child birth to allow passage of foetus
• Vagina


  -semen is deposited in the vagina during sexual intercourse

  -menstrual blood flows out of the vagina during menstruation
• Menstruation


  Uterine lining and unfertilised egg break down and are shed with some blood

  (oestrogen & progesterone concentration is low)
• Menstruation period


  Day 1 to 5
• Repair and thickening of uterine lining


  Ovary produces oestrogen, which causes uterine lining to repair and thicken

  (oestrogen concentration increases & progesterone concentration is low)
• Repair and thickening of uterine lining period

  Day 6 to 15
• Fertile period


  Fertilisation is most likely to occur with sexual intercourse (oestrogen concentration increases & progesterone concentration is low)
• Fertile period (period)


  Day 10 to 15
• Ovulation


  Release of mature egg (oestrogen concentration is high & progesterone starts to increase after this day)
• Ovulation period


  Day 14
• Further thickening of uterine lining


  ovary produces progesterone (oestrogen concentration decreases and progesterone increases and maintains high until menstruation)
• Progesterone


  Prevents ovulation and further development of eggs, this hormone also thicken uterine lining further to prepare for implantation and growth and embryo
• Further thickening of uterine lining period

  Day 16 to 28
• What happens during ovulation


  The mature egg is released from the ovary at day 14
• What happens during fertilisation


  Sperm nucleus and egg nucleus fuses in the fallopian tube to form a zygote
• What happens when the zygote is moving to the uterus


  Peristalsis and cilia on fallopian tube sweep zygote towards the uterus
• What happens when the zygote divides


  It divides by mitosis into embryo while being swept into the uterus
• What happens during implantation


  Embryo is implanted into the uterine lining. Placenta, umbilical cord & amniotic sac starts to develop. Placenta takes over the role of oestrogen and progesterone
• Pathogen: HIV (human immunodeficiency virus)


  -HIV destroys the body's immune system by destroying the lymphocytes

  -HIV is spread through contact with bodily fluids such as the semen and blood of an infected person
• Disease: AIDS (Acquired Immune Deficiency Syndrome)


  -AIDS is a STI (sexually transmitted infection)

  -AIDS refers to the most advanced stages of HIV infections
• Methods HIV is transmitted through


  -Unprotected sexual intercourse with an infected person

  -Passed from infected mother to foetus during pregnancy

  -blood transfusion with blood from an infected person

  -sharing of hypodermic needles with an infected person
• Methods which HIV may be controlled


  -keep to one sex partner/do not have sex with an infected person

  -use a condom when having sexual intercourse to reduce risk of infection

  -make sure that the needles used in acupuncture, ear-piercing and/tattooing are sterilised

  -do not abuse during as drug addicts tend to share needles

  -do not share instruments that can break skin and get contaminated with blood (eg; razors, toothbrushes)