Sexual reproduction

• What is sexual reproduction

  Sexual reproduction is defined as the fusion of nuclei of the male and female gametes to form a zygote, which develops into genetically unidentical offspring
• What are gametes

  Gametes are sex cells produced by male and female reproductive organs. The human gamete’s are the sperm and ovum. Each gamete contains half of the dna of the individual that produced it, in its nucleus
• how are traits of parents inherited by their children

  In a sperm or ovum nucleus, only one member of each pair of chromosomes is present

  During fertilisation, the 23 chromosomes in the sperm and the 23 chromosomes in the ovum combine. The offspring thus inherits traits randomly from the father and the mother.
• What is puberty

  Is the onset of sexual maturity in the human body. This marks the time when the body becomes biologically capable of reproduction.
• Puberty in both sexes

  Height and weight increase

  growth of armpit and pubic hair

  production and maturation of gametes begin
• Puberty in males

  Voice deepens

  muscle strength increases

  sperm production begins
• Puberty in females

  Breasts begin to develop

  hips become broader and rounder

  maturation of ove begins
• Testis function

  Each testis produces sperm and male sex hormones such as testosteron. The male hormones are responsible for the development and maintenance of the secondary sexual characteristics in males.
• Scrotum function testes lie in a pouch- like sac called the scrotum.

  outside the main body cavity. Thus it is at a slightly lower temperature than body temperature . the lower body temp is essential for sperm to develop properly
• Sperm duct function

  Each sperm duct loops over a ureter and and then opens into the urethra

  after sperm are released from a testis, they travel through a sperm duct.
• Prostate gland and it’s secretions

  The prostate gland is at the base of the urinary bladder where the two sperm ducts join the urethra

  the prostate gland secretes a fluid which mixes with the sperm. This fluid contains nutrients and enzymes which nourusg the sperm and stimulate them to swim actively. The mixture of the fluid and sperm is called semen.
• Urethra

  A tube which passes from the bladder through the centre of the penis to the outside of the body

  both semen and urine pass out of the body through the urethra
• Penis


  Is an erectile organ

  enters the vagina of a woman during sexual intercourse to deposit semen, containing sperm
• Differences between male and female gametes

  1. sperm much smaller in size than ova
  2. sperms are mobile, they can move on their own but ovum is immobile
  3. one ovary releases one ovum per month but 100 Million sperms are released every time the male ejaculates
• Ovary function


  produce ova and hormones such as oestrogen and progesterone which are responsible for the development and maintenance of the secondary sexual characteristics in females

  When eggs become mature they are released from the ovaries
• Oviduct function

  • Each ovary releases mature eggs into an oviduct.
  • Each oviduct is a narrow muscular tube leading from the ovary to the uterus. It has a funnel-like opening lying close to the ovary. This makes it easier for the egg to enter the oviduct.
  • The egg is usually fertilised in the oviduct.
  • The inner surface of the oviduct is lined with cilia. The movement of the cilia helps to move the egg along the oviduct.
• Uterus function

  The uterus is where the fetus develops during pregnancy.

  • The uterus is shaped like an upside-down pear. It has elastic muscular walls. The smooth muscle tissue in the walls of the uterus contract-to push the fetus out during birth.
  • The soft, smooth inner lining of the uterus is called the uterine lining. It is where the embryo is implanted.
• Cervix function

  ring of muscles at the lower portion of the uterus where it joins the the vagina

  the opening if the cervix allows menustral blood to flow out into the vagina during menustration
• vagina function

  Leads from the cervix to the outside

  semen is deposited in the vagina during sexual intercourse
• What happens during menstruation

  Uterine lining breaks from days 1 to 5
• Repair of uterine lining 


  Uterine lining repairs and thickens from days 6 to 13 to prepare for implantation of embryo
• Ovulation


  The release of the mature ovum on day 14
• Uterine lining remains thick


  From days 15 to 28 to prepare for possible implantation of embryo
• What are some temporary contraceptive methods

  Condom prevents sperm from entering vagine

  spermicide kills sperm

  intra-uterine device prevents implantation of embryo on the uterine lining

  contraceptive pills prevents ovulation

  diaphragm prevents sperm from entering uterus
• Permanent contraceptive methods

  Vasectomy- the sperm ducts are tied and cut. Prevents sperm from entering the urethra

  ligation- the oviducts are cut and tied. Prevents ovum from being fertilised by sperm.
• Reasons for growth of human population


  Increased food production

  improved sanitation

  improved healthcare
• Common STI and if it’s bacterial


  HIV/AIDS acquired immunodeficiency symptoms

  gonnorhea and syphillis bacterial
• How can STIs be treated and how are they spread

  HIV spread from person to person through contact with body fluids

  people w aids can take medication to prolong life

  bacterial STIs can be treated with antibiotics