Human Sexual Reproduction

Human Sexual Reproduction

1. Fusion of an egg from the female and a sperm from the male to form a new individual

   • Ensures that a species survives

2. Puberty

   • Boys
     • Testes produce sex hormones and sperms
     • Ejaculation begins
     • Testes and penis increase in size
     • Height increases rapidly
     • Body becomes more muscular and shoulders broaden
     • Hair grows on face, chest, in armpits and pubic regions
     • Voice box enlarges causing voice to deepen
   • Girls
     • Ovaries produce sex hormones and release mature eggs
     • Menstruation begins
     • Breasts and uterus(womb) increase in size
     • Height increases rapidly
     • Hair grows in armpits and pubic regions
   • Details
     • Period of rapid growth
     • Period of sexual maturation during which the sexual reproductive system becomes fully fuctional
       • Becomes capable of sexual reproduction
     • Usually begins between 9 - 15 years old
       • Starts earlier in girls
     • Change is brought about by sex hormones

3. Reproductive System

   • Males
     • Sperm
       • Head
       • Flagellum
         • Propel the sperm forward
       • Nuclues
         • Contains DNA(determines the gender)
       • Middle Piece
         • Connects the head and flagellum
     • Male Sex Hormones
       • Testosterone
     • Parts
       • Sex Gland
         • Release Fluids
           • Protect the sperms and nourish them with energy to swim
         • Sperm + Fluids
           • Semen
       • Sperm Duct
         • Carry sperms from epididymis to uthera
       • Uretha
         • Carries sperms from sperm duct to the outside of the body
           • Through the penis
       • Epididymis
         • Temporary storage for sperms before ejaculation
       • Testes
         • Produces sperms and male sex hormones
       • Scrotum
         • Layer of skin
         • Holds the testes in a sac outside the body where it is cooler
           • Lower temperature needed for healthy sperm production
   • Females
     • Female Sex Hormones
       • Oestrogen
         • Repaires uterus lining
         • When drops, an egg is released
           • Ovulation
       • Progesterone
         • Further thickening of uterus lining
         • When drops, the uterus lining sheds
           • Menstrate
     • Egg
       • Cytoplasm
       • Nucleus
         • Contains DNA(determines the gender)
       • Cell Membrane
     • Parts
       • Fallopian Tubes
         • Carries the Mature Egg
           • From the ovary to the uterus
         • Tiny hair-like projection called cilia line the wall
           • Sweep the egg along the uterus
       • Uterus
         • Muscular pear-shaped structure where the embryo develops during pregnancy
       • Ovary
         • Produces ova or eggs and female sex hormones
       • Cervix
         • Neck of the uterus which widens during childbirth
       • Vagina
         • Muscular tube where sperms are deposited during sexual intercourse
         • Widens during childbirth

4. Menstruation

   • Ovulation
     • A mature egg is released from one of the ovaries into the fallopian tube
       • About once every 28 days
       • On the way to the uterus it may be fertilised by a sperm
   • Thickening of uterus lining
     • Uterus prepares itself to receive any fertilised egg which will develop inside it
     • Lining becomes thick and spongy and full of blood capillaries
     • Rich supply of blood capillaries help to supply the egg with nutrients
   • Menstrual cramps
     • The contractions of the uterus to push the disintegrated uterus lining and blood out of the body
   • Menstrual Cycles
     • Ovulation occurs again about two weeks after the first day of menstruation
     • If the egg is not fertilised, menstruation occurs again
     • Typically last 28 days
       • Day 1 - 6 : Menstruation - uterus lining breaks down
         • Day 7 - 10 : Uterus lining starts to build up again
           • Day 11 - 16 : Fertile Period
             • Day 17 - 28 : Uterus lining becomes thick and spongy and full of blood capillaries
   • Menopause
     • Occurs when ovulation and menstruation stop
     • A woman cannot have a baby naturally when she reaches menopause
   • Is the discharge of the disintegrated uterus lining, unfertilised egg and blood through the vagina
   • if no fertilised egg enters the uterus after about a week, the thick uterus lining starts to break down
     • The disintegrated uterus lining and the unfertilised egg, together with blood will be discharged out of the body through the vagina
       • Over a period of 3 to 7 days

5. Fertillsation

   • Zygote
     • First single cell formed after fertilisation
   • Embryo
     • It divides repeatedly forming ball of cells
   • Foetus
     • Continues dividing to form new cells
     • The cells differentiate
       • All the major organs are fomed
   • Placenta
     • Foetus gets nourishment from the mother
     • Has a rich supply of blood vessels
   • Gestation
     • Period when the foetus is ready to emerge from the mother's body
     • The baby is pushed out of the body through the vagina by strong muscular contractions of the uterus
   • Chromosomes
     • DNA
       • Packed with proteins
       • Genes
         • Inherit chracteristics
           • Passed from parents to offspring
             • The sperm have one set of chromosomes each
             • Receives genetic information
   • Heredity
     • The transmission of genetic characteristics from parents to offspring
     • Each of us is a unique individual as we inherit a combination of genes from both parents
   • Birth Control/Contraception
     • Prevention of pregnacies
       • Prevents fertilisation
       • Prevents ovulation
       • Prevents development of a fertilised egg
     • Helps in family planning
     • Contraceptive Methods
       • Temporary
         • Shot terms effect
         • Can decide to stop using
       • Permanent
         • Sterilisation
           • Ability to reproduce is permanently removed
           • Male
             • Vasectory
               • Cutting and tying up both sperm ducts
           • Female
             • Ligation
               • cutting and tying both fallopian tubes
           • Eggs and sperm are naturally absorbed by the bodies
         • Fertilisation no longer occurs
       • Not fool proof

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