Prenatal Development

Week 3 to week 8
1. Embryonic stage
  1. one implantation has occurred Organism is now known as the embryo
    1. 2cm in length
  2. Cell Differentiation
    1. Cells take on specialised roles
      1. Heart Cells
      2. Skin Cells
  3. Most critical stage for human development
    1. begins to develop all major organs
      1. Brain
      2. Spinal Cord
      3. Heart
      4. By the end of this stage, all major organs are present and will continue to develop
  4. Sex cells begin to develop
    1. Cannot determine if male/female yet
  5. Limbs start to bud
    1. Eventually form fingers and toes
  6. By week 8, 90% of structures found in an adult human can be identified
    1. starts to look human looking
    2. Head and neck account for half the total length
    3. Brain makes up half of its body weight
  7. sensitive during this stage to environmental influences
    1. Teratogens
      1. Tobacco
      2. Alcohol
      3. Medication
Week 8 to Week 40/birth
1. Foetal Stage
  1. Embryo is now known as foetus
  2. Characterised by Rapid growth
    1. Measures only a few cm long at beginning
      1. Ends stage at 50cm
  3. Systems begin to function
    1. Lungs
    2. Digestive system
    3. Liver
    4. Kidneys
  4. Sex organs start taking shape by week 15.
    1. Identify Sex by ultrasound
    2. Female
      1. Produces millions of eggs
    3. Male
      1. Testes produce testosterone
  5. Movement and reflexes occurs
    1. Sucking
    2. Grasping
  6. Breathing movements occur
    1. No air but amniotic fluid
  7. Bones Harden
    1. Tooth buds form in gums
  8. Senses begin to function
    1. Sound
    2. Light
    3. Touch
Conception to week 2
1. Germinal Stage
  1. Zygote
    1. Forms when a sperm and ova meet
    2. Travels down the fallopian tube and constantly divides
  2. Morula
    1. At approx. 16 cells (day 3-4) starts to form a spherical shape
  3. Blastocyst
    1. At approx. 64 cells (day 5) begins to form a hollow fluid centre, an inner mass and an outer mass
      1. Inner cell becomes embryo
      2. Outer cell becomes placenta
    2. At approx. day 7/8 blastocyst attaches to the wall of the uterus
      1. Fully implanted by day 11-15
Placenta
1. Formed and fully functioning in embryonic stage
2. Temporary organ
  1. Acts as kidney, lung and digestive system for the foetus
    1. Supplies oxygen
    2. Delivers nutrients and hormones
    3. Removes waste (urine and carbon dioxide
    4. Provides Immune Support
3. Connected through the foetus through the umbilical cord
  1. Made up of two artiries
    1. Oxygenated/nutrient rich
    2. Deoxygenated/nutrient depleted
  2. Exchange of substances between mother and baby occur through thing walls of placenta
4. Produces hormones that helps maintain pregnancy

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Prenatal Development

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	Created by awebber about 9 years ago

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