Reproduction in humans

• What is sexual reproduction?

  A process involving the fusion of nuclei of male and female gametes(sperm cell and egg cell) this forms zygote during fertilisation and produces genetically dissimilar offspring
• Parts of the male reproductive system 


  Testis, scrotum, sperm duct, prostate gland, urethra, penis
• Function of testis(gonad)


  Produces sperm(male gamete), produces male sex hormones(testosterone)
• Function of scrotum

  Pouch-like sacs located outside the body, maintain lower temperature for development of sperms
• Function of sperm duct

  Transports sperms released from the testis to the urethra
• Function of prostate gland

  Secretes a fluid containing nutrients and enzymes that nourish the sperm and stimulate them to swim actively, mixture of this fluid and sperm is called semen
• Function of urethra

  Tube that extents from the bladder through the penis outside the body, both urine and semen exit the body through the urethra but never at the same time
• Function of penis

  Erectile organ, becomes erect during sexual intercourse in order to deposit semen into the vagina, erection occurs when the spongy tissue in the penis is filled with blood
• Function of ovary (gonad)


  Produces eggs/ ova (female gametes), produces female sex hormones (oestrogen and progesterone)
• Function of oviduct

  A narrow muscular tube with a funnel-like opening at the ovary, mature eggs are released from the ovary into the oviduct, fertilisation occurs in the oviduct
• Function of uterus

  Embryo is implanted in the uterine lining, the site where fetus develops during pregnancy, has elastic muscular walls that enable contraction during birth to expel the fetus
• Function of cervix

  the circular ring of muscle at the lower portion of uterus, the opening of the cervix allows menstrual blood to flow out into the vagina during menstruation
• Function of vagina

  The location where semen is deposited during sexual intercourse
• How long is a menstrual cycle

  Average length of a menstrual cycle is 28 days, three is a natural variation in the length of the menstrual cycle ranging from 21 to 33 days. The menstrual cycle can be affected by stress, illness, unbalanced diet, and or malnutrition
• Day 0-5 is menstruation

  • the uterine longing breaks down and is shed with some blood out of the body through the vagina
  • Concentration of oestrogen is Low + progesterone is low
• Day 6-13 is after menstruation

  • the ovary produces the hormone oestroge, which causes the repair and growth of the uterine lining
  • Concentration of oestrogen increases + progesterone is Low
• Day 14 is ovulation

  • the ovary releases an egg into the oviduct
  • Concentration of oestrogen is high + progesterone is Low
• Day 15-18 is after ovulation

  • the ovary produces the hormone progesteron, which prevents ovulation and further development of eggs, progest also causes the further thickening of the uterine lining for the implantation of embryo
  • Concentration of oestrogen is decreases + progesterone is increasing
• What is fertilisation

  When the sperm makes contact with the egg, the doers acrosome releases an enzyme that breaks down part of the egg membrane to allow the sperm to enter, fertilisation occurs when the nucleus of a sperm fuses with the nucleus of an ovum to form a zygote, fertilisation usually occurs in the oviduct
• What happens during the early development of the zygote

  The cilia lining the oviduct sweep the zygote along the oviduct towards the uterus, as the zygote travels along the oviduct, it undergoes cell division to form a ball of cells, and eventually into an embryo, the embryo becomes implanted in the wall of the uterus
• How is the human immunodeficiency virus transmitted

  Acquired immunodeficiency syndrome (AIDS) is a sexually transmitted infection that is caused by the human immunodeficiency virus (HIV)
• HIV destroys the body’s immune system. A person infected with AIDS is not able to produce suffi isn’t antibiotics to protect his or herself from other infection, infections that are normally mild may become fatal for a person with AIDS
• HIV can be transmitted by

  • unprotected sexual interdicted with an infected person (exchange by semen and fluid in the vagina)
  • transfusion of contaminated blood from an infected person (exchange by blood)
  • sharing of contaminated needles with an infected person (exchange by blood)
  • from a mother to fetus during pregnancy, childbirth and breastfeeding (exchange by blood and breast milk)
• How can the transmission of human immunodeficiency virus be reduced

  • abstain from sex
  • keep to one sex partner
  • use a condom when having sexual intercourse
  • do not share instruments that can break skin and get contaminated with blood
  • ensure that the needles used in acupunctur, ear-piercing and or tattooing are sterilised
  • do not abuse drugs addicts attend to share needles
• Fertile phase

  Day 10-15 when sexual intercourse takes place during the fertile phase between day 10 to day 15, pregnancy may occur as- sperms may survive in the female reproductive system (eg. vagina, oviduct and uterus) for serval days until ovulation on day 14
• Infertile phase

  The rest of the days make up the infertile phase of the menstrual cycle, pregnancy is unlikely to occur if there is no egg cell released or if the egg cell has died, hence fertilisation would not occur
• What happens during each menstrual cycle

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