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Human Reproduction
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Battle of the sexes!!!Are males andfemales all that
different?Well…..
Yes
And
No!
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Similarities2 pouches
Testicles
Ovaries
Start out inside body
Testicles “descend” before birth
Fetus begins with “starter parts”that could develop into eithergender.
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Around 7th Week…Baby’s body is “told” by DNA tobecome either male or female.
“Unused” parts disintegrate
“Used” parts continuedevelopment
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Male or Female???DNA determines baby’s gender
XX = Female
XY = Male
Depends on which egg & spermget together.
Father determines baby’s gender.
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Male
Uncomplicated
Produce sperm2-4 MILLIONevery day
Female
Very Complicated!
One eggOnce a month
Carefulcoordination of
hormones & body Timing perfect!
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FemalesOvaries
2 pouches
Contain ovaBorn with all of her eggs (~ 400,000)
Use up ~500
Won’t run out!
OvulationOne egg released from ovary tooviduct (fallopian tube)
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After OvulationEgg pushed along by cilia
Few days travel time to arrive in uterus
Cervix – Opening between uterus &vagina
Normally tinyAt birth – muscles pull open (dilation) cervixto allow baby to pass through = Labor
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28-Day Cycle (average) Three Stages
1. Tear Down
2. Rebuild3. Extra nutrients/blood for potential baby
No Baby?Back to #1
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If fertilized…Zygote begins to divide as ittravels through oviduct
Implants into lining of uterus
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If not fertilized…Egg travels through oviduct touterus
Exits body with blood and tissuesduring menstruation
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Birth Control Pills“Trick” body into thinking it’s pregnant
Extra hormones
No ovulation occursNo ovulation = no egg = no fertilization = nobaby!
No hormones taken for 7 days = menstruation
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Male Testes
Produce 2-4 million sperm every day
Outside body – why?Sperm like temps 1-2° cooler than bodytemp
Vas Deferens
Tube sperm travel throughVasectomy
Cut/tie off tube – sperm can’t get out!
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SemenContains
300-500 million sperm
Sperm nutrients
pH buffers
Allows sperm to survive for a
couple of days inside female’sbody (hostile environment)
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What is sperm? Then…
Used to think it was a tiny
human inside each cellSpermists vs. Ovists
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Now…Contains SeveralParts:
HeadChemical todissolve egg goo
Dad’s geneticinformation (DNA)
MitochondriaEnergy
TailSwimming
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Conception/Fertilization
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Once egg is located…Dissolve protective goo surrounding egg
One gets through – enters eggInstant biochemical change in zygote
No more sperm allowed in
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Zygote beginsdevelopment
Time Lapse Develop
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Implants in uterine lining
Endometrium= outer lining of uterusBecomes placenta
Uses mother’s nutrients
Continues development
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Fetal DevelopmentAnmion
Membrane surrounding baby
Contains amniotic fluidBreaks just before birth = “waterbroke”
Amniotic Fluid
The “water” – surrounding baby
Buoyant cradle for babyProtection
Free movement
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Fetal Dev (cont’d)Umbilical Cord
Blood vessels from placenta to baby
Mom’s & baby’s blood do not circulatetogether!
Can have 2 different blood types
Diffusion
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