Human Reproduction

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Human Reproduction
Courtesy of Hartford Union High School
District (www.huhs.org/departments/science/.../Hu
man20Reproduction.ppt)Edited by Georgia CTAE
Resource Network
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Battle of the Sexes!!!

• Are males and females all that different?
• Well..
• Yes
• and
• No!

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Anatomy
Male
Female
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Similarities

• 2 pouches
• Testicles
• Ovaries
• Start out inside body
• Testicles descend before birth
• Fetus begins with starter parts that could
  develop into either gender

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Around 7th Week

• Babys body is told by DNA to become either
  male or female
• Unused parts disintegrate
• Used parts continue development

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Male or Female???

• DNA determines babys gender
• XX Female
• XY Male
• Depends on which egg sperm get together
• Father determines babys gender

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Anatomy similaritiesFunction VERY different!

• Male
• Uncomplicated
• Produce sperm
• 2-4 MILLION every day

• Female
• Very Complicated!
• One egg
• Once a month
• Careful coordination of hormones body
• Timing perfect!

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Females

• Ovaries
• 2 pouches
• Contain ova
• Born with all of her eggs ( 400,000)
• Use up 500
• Wont run out!
• Ovulation
• One egg released from ovary to oviduct (fallopian
  tube)

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After Ovulation

• Egg pushed along by cilia
• Few days travel time to arrive in uterus
• Cervix Opening between uterus vagina
• Normally tiny
• At birth muscles pull open (dilation) cervix to
  allow baby to pass through Labor

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Menstrual Cycle

• Complex combination of 10-12 chemicals (hormones)
• Usually one egg once a month
• All about timing!
• Uterus must be ready when egg gets there in case
  it was fertilized
• If no fertilization, tear down lining of uterus
  and rebuild for next month

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28-Day Cycle (Average)

• Three Stages
• Tear Down
• Rebuild
• Extra nutrients/blood for potential baby
• No Baby?
• Back to 1

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Chemicals (Hormones)

• Regulate events in the body
• Estrogen
• Progesterone
• LH (leuteinizing hormone)
• FSH (Follicle Stimulating Hormone)
• Many others

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Day 1

• First menstrual blood tissue
• No baby breaks down lining of uterus
• 5-7 days of blood/tissue exits body

Pre-Ovulation
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Day 14

• Ovulation Egg released
• Temperature spikes slightly
• Most fertile in next few days!
• Able to get pregnant
• Egg gets fertilized while traveling through
  oviduct

Post-Ovulation
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If fertilized

• Zygote begins to divide as it travels through
  oviduct
• Implants into lining of uterus

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If not fertilized

• Egg travels through oviduct to uterus
• Exits body with blood and tissues during
  menstruation

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Birth Control Pills

• Trick body into thinking its pregnant
• Extra hormones
• No ovulation occurs
• No ovulation no egg no fertilization no
  baby!
• 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 body temp
• Vas Deferens
• Tube sperm travel through.
• Vasectomy
• Cut/tie off tube sperm cant get out!

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http//en.wikibooks.org/wiki/Human_Physiology/The_
male_reproductive_system
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Semen

• Contains
• 300-500 million sperm
• Sperm food
• pH buffers
• Allows sperm to survive for a couple of days
  inside females body (hostile environment)

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What is sperm?

• Then
• Used to think it was a tiny human inside each
  cell
• Spermists vs. Ovists

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Now

• Contains Several Parts
• Head
• Chemical to dissolve egg goo
• Dads genetic information (DNA)
• Mitochondria
• Energy
• Tail
• Swimming

http//en.wikibooks.org/wiki/Human_Physiology/The_
male_reproductive_system
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Prostate Gland

• Adds non-sperm stuff to semen
• pH buffers
• Nourishment
• Cancer very common
• Slower-growing (usually)
• Surgery for removal

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Bulbourethral Gland

• Adds lubricant to aid travel of semen through the
  urethra

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Conception/Fertilization
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Conception/Fertilization

• Ejaculation
• Release of 300-500 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 attacked by females white blood cells
• Acidic environment
• Current

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Once egg is located

• Dissolves protective goo surrounding egg.
• One gets through enters egg
• Instant biochemical change in zygote
• No more sperm allowed in

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Zygote Begins Development
Zygote a fertilized egg
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Implants in Uterine Lining

• Endometrium outer lining of uterus
• Becomes placenta
• Uses mothers nutrients
• Continues development

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Fetal Development

• Amnion
• Membrane surrounding baby
• Contains amniotic fluid
• Breaks just before birth water broke
• Amniotic Fluid
• The water surrounding baby
• Buoyant cradle for baby
• Protection
• Free movement

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Fetal Development (contd)

• Umbilical Cord
• Blood vessels from placenta to baby
• Moms babys blood do not circulate together!
• Can have 2 different blood types
• Diffusion

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Birth

• Labor muscles used to open cervix
• Baby flips upside down
• Head first!
• Feet first Breech (bad)
• Cesarean Section (C-section) - surgical removal
  of baby
• After baby is born, mom delivers placenta
  (afterbirth) that detaches from uterus

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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 with baby is stronger

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Twins/Multiple Births

• Two types
• Monozygotic
• From one egg
• Identical
• Dizygotic
• From two eggs
• Fraternal
• Not identical

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Identical twins

• One zygote
• Splits in 2
• No one knows why!
• Completely random does NOT run in families
• Same exact DNA
• Natures clones

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Fraternal Twins

• 2 separate eggs get fertilized with 2 different
  sperm cells
• More than one egg got released during ovulation
• Can be
• Sisters
• Brothers
• Brother and sister
• Tends to run in families

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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

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