16: Sexual Reproduction

• What is sexual reproduction

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

  Sex cells produced by male and female reproductive organs. The human gametes are the sperm and the ovum. Each gamete contains half of the DNA of the individual that produced it in its nucleus
• How many chromosomes do human cells have

  23 pairs of chromosomes
• What is puberty

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

  • height and weight increase
  • growth of public and armpit hair
  • production and maturation of gametes begins
• Puberty in males

  • voice deepens muscle strength increases
  • message strength increases
  • sperm production increases
• Puberty in females

  • breasts begin to develop
  • hips becomes broader and rounder
  • maturation of ova begins
• Testis


  There are two testes. Each test is produces sperm and make sex hormones such as testosterone. The male hormones are responsible for the development and maintenance of the secondary sexual characteristics in males
• Scrotum


  Testes lie in a pouch-like sac called the scrotum

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

  Each sperm duct loops over a ureter than opens into the urethra. After sperm are released from a test is, they travel through a sperm duct.
• Prostate gland and it’s secretions

  The prostrate 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 nourish the sperm and stimulate them to swim actively. The mixture of fluid and sperm is called semen
• Urethra


  Tube which passes from the bladder through the centre of the penis to outside of the body. Both semen and ruined pass out of the body through the urethre
• Penis

  Erectile organ

  enters the vagina during sexual intercourse to deposit semen containing sperm
• Is the male gamete mobile

  Sperm is mobile, it can swim on its own
• Ovary

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

  when the eggs become mature, they are released from the ovaries
• Oviduct

  Each ovary releases mature eggs into an oviduct which is a narrow muscular tube leading from the ovary to the uterus. it has a funnel like opening lying close to the ovary which makes it easier for the egg to enter the oviduct

  the egg is fertilised in the oviduct

  the inner surface of the oviduct is lined with cilia. The movement of cilia helps to move the egg along the oviduct
• Uterus


  is where the fetus develops during pregnancy

  shaped like an upside down pear. it has elastic muscular walls. The smooth muscle tissue in the walls of the uterus is called the uterine lining where the embryo is implanted
• Cervix


  Ring of muscles at the lower portion of the uterus where it joins the vagina. The opening of the cervix allows menstrual blood to flow out into the vagus during menstruation
• Vagina

  Leads from the Cervix the the outside

  segment is deposited here during sexual intercourse
• Sequence of events leading up to fertilisation

  • penis deposits semen containing sperm cells in the vagina
  • the sperm cells swim through the cervix into the uterus and into the oviduct
  • a sperm cell meets an egg cell in the oviduct
  • fertilisation occurs when the nucleus of the sperm cell fuses with the nucleus of the egg cell while all the other sperm cells die
• Menstrual cycle

  1. Menstruation: uterine lining breaks down from days 1 to 5
  2. repair and thickening of uterine lining breaks down: uterine lining repairs and thickens from days 6-13 to prepare for implantation of embryo
  3. ovulation : the release of the mature ovum on day 14
  4. uterine lining remains thick : from days 15-28 to prepare for possible implantation of embryo
• What is a condom made of?


  Latex
• How does a condom function during sexual intercourse?

  A condom prevents sperm from entering the vagina
• What is spermicide?

  A gel that kills sperm
• How is spermicide typically used?

  Usually used in conjunction with a condom
• What is an intra-uterine device (IUD) made of?

  Copper
• What is the primary function of an IUD?

  Prevents implantation of the embryo on the uterine lining
• What are contraceptive pills?

  A type of oral medication
• What do contraceptive pills prevent?

  They prevent ovulation
• What is a diaphragm in the context of contraception?

  A barrier inserted near the woman’s cervix
• How does a diaphragm function?

  It prevents sperm from entering the uterus
• What are the temporary contraceptive methods mentioned?

  • Condom
  • Spermicide
  • Intra-uterine device (IUD)
  • Contraceptive pills
  • Diaphragm
• What are the permanent contraceptive methods

  Vasectomy

  ligation
• What is vasectomy


  the down ducts of the male are cut and tied. prevents sperm from entering the urethra
• What is ligation

  The oviducts of the female are cut and tied. Prevents ovum from being fertilised by sperm
• What is HIV / AIDS and how can it be spread

  HIV- human immunodeficiency virus

  AIDS acquired immune deficiency syndrome

  can be shoes from person to person through contact with body fluids like se men, vaginal fluid and blood
• What can be treated with antibiotics

  Bacterial STIs such as syphillis and gonorrhea