1. Human Reproduction

2. Conception/Fertilization

3. Conception/Fertilization
Ejaculation
Release of million sperm
Egg needs to be in oviduct
Sperm to egg, not an easy task
Go wrong direction
2 paths – only 1 leads to an egg
Get distracted or confused
Get attacked by female’s white blood cells
Acidic environment
Current

4. Once egg is located… Dissolve protective goo surrounding egg
One gets through – enters egg
Instant biochemical change in zygote
No more sperm allowed in

5. Zygote begins development

6. Implants in uterine lining
Endometrium= outer lining of uterus
Becomes placenta
Embryo supported via umbilical cord
Uses mother’s nutrients
Continues development
Once pregnant, progesterone levels stay high in mom

7. Fetal Development Anmion Amniotic Fluid Membrane surrounding baby
Contains amniotic fluid
Breaks just before birth
Amniotic Fluid
The “water” surrounding baby
Buoyant cradle for baby
Protection
Free movement\
To reduce temperature fluctuation
To lubricate the vagina during birth

8. Fetal Development Umbilical Cord Placenta
Blood vessels from placenta to baby
Mom’s & baby’s blood do not circulate together!
Can have 2 different blood types
Diffusion
Placenta
As a place of exchange of materials between mother and the fetus
For secreting hormones

9. The Placenta
Finger-like villi increases the surface area for efficient diffusion
Maternal blood and fetal blood flows in opposite direction to speed up diffusion of materials between them
Maternal blood capillaries and fetal blood capillaries are separated by thin membrane
to shorten the distance of diffusion of materials
to prevent high pressure of maternal blood from breaking the delicate fetal blood vessels
to prevent clotting of maternal and fetal blood if their blood groups are incompatible

10. 6 weeks Heart has already formed
Neural tube has formed and nervous system continues to develop
1/5 – ¼ of an inch long
Folds at anterior end will become jaws, cheeks and chin
Ear canals have begun
Kidneys, liver and lungs are forming

11. 9 weeks Is now called a fetus 1” long
Spleen and gal bladder are forming
Beginning of external ears
Spontaneous movements – can’t be felt by mom yet
Heartbeat can be heard

12. 12 weeks Most systems are fully formed 2 ½” long and ½ ounce
Tripled in size in the last three weeks!!
Pituitary gland has begun producing hormones
Bone marrow is making white blood cells
Mom may barely “show”

13. 2nd Trimester Mostly growth Looks more like a baby
Some preemies survive at this stage

14. 15 weeks 4 ½” long and 2 ounces
Ears are on the side of the head (they started out on the neck!)
Eyes are moving to the front of the face form the side of the head
Baby is practicing breathing, sucking, moving, and swallowing
Mom now has a “bump”

15. 18 weeks 5 ½” long and 5 ounces
Rolls, kicks, and punches can now be felt by mom
Myelin now covers the nerves
Sensory areas of the brain are specializing
Baby gets the hiccups

16. 20 weeks – half way there!! 6 ½” long and 10 ounces
A boy or a girl?? External genitalia can be seen at this point
Testicles are starting to descend, vagina is forming
Can control movements
Taste buds begin to develop

17. 24 weeks 8 ½” long and more than a pound Packing on the fat
Organs are growing
Has hair now
Skin is thin and transparent

18. 3rd Trimester More growth Kicking, rolling, stretching
Eyes open – Week 32
Lungs mature
Rotates to head-down
position

19. Birth Labor – muscles used to open cervix Baby flips upside down
Head first!
Feet first = Breech (bad)
Cesarian Section (“C-section”) surgical removal of baby
After baby is born mom delivers placenta (“afterbirth”) that detaches from uterus

20. Breastfeeding Most nutritious option for baby
Milk changes as baby grows
Antibodies from mom create immunity for baby
Studies have shown correlation between breastfeeding and higher intelligence in baby.
Bond w/baby is stronger

21. Twins/Multiple Births
Two types
Monozygotic
From one egg
Identical
Dizygotic
From two eggs
Fraternal
Not identical

22. Identical twins One zygote Splits in 2 No one knows why!
Completely random = does NOT run in families
Same exact DNA
Nature’s clones

23. Fraternal Twins
2 separate eggs get fertilized with 2 different sperm cells
More than one egg got released during ovulation
Siblings
Can be sisters
Brothers
Brother and sister
Tends to run in families

24. Conjoined Twins Used to be called “Siamese” twins
First well known case was in Siam
Identical twins that never completely separated during development
Sometimes can be separated, depending on what is shared.