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Human Reproduction.

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Presentation on theme: "Human Reproduction."— Presentation transcript:

1 Human Reproduction

2 Human Reproductive System
Male Female

3 Male or Female??? DNA determines baby’s gender XX = Female XY = Male
Depends on which egg & sperm get together. Father determines baby’s gender.

4 Male Female Uncomplicated Produce sperm 2-4 MILLION every day
Very Complicated! One egg Once a month Careful coordination of hormones & body Timing perfect!

5 Females Ovaries Ovulation 2 pouches
Contain ova Born with all of her eggs (~ 400,000) Use up ~500 Won’t run out! Ovulation One egg released from ovary to oviduct (fallopian tube)


7 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

8 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

9 28-Day Cycle (average) Three Stages No Baby? Tear Down Rebuild
Extra nutrients/blood for potential baby No Baby? Back to #1

10 Chemicals (hormones) Regulate events in the body Estrogen Progesterone
Many others

11 Day 1 Pre-Ovulation First menstrual blood & tissue
No baby = breaks down lining of uterus 5-7 days of blood/tissue exits body Pre-Ovulation

12 ~Day 14 Post-Ovulation Ovulation = Egg released Temp spikes slightly
Most fertile in next few days! Able to get pregnant Egg gets fertilized while traveling through oviduct. Post-Ovulation

13 If fertilized… Zygote begins to divide as it travels through oviduct
Implants into lining of uterus

14 If not fertilized… Egg travels through oviduct to uterus
Exits body with blood and tissues during menstruation

15 Birth Control Pills “Trick” body into thinking it’s pregnant
Extra hormones No ovulation occurs No ovulation = no egg = no fertilization = no baby!

16 Male Testes Vas Deferens 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

17 Semen Contains million sperm Sperm food pH buffers Allows sperm to survive for a couple of days inside female’s body

18 Now… Contains Several Parts: Head Mitochondria Tail
Chemical to dissolve egg goo Dad’s genetic information (DNA) Mitochondria Energy Tail Swimming

19 Prostate Gland Adds stuff to semen pH buffers Nourishment

20 Conception/Fertilization

21 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 attacked by female’s white blood cells Acidic environment Current

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

23 Gamete – Sex cell; sperm and ova
Zygote – Cell formed after male and female gametes join immediately following fertilization

24 Zygote begins development

25 Implants in uterine lining
Blastocyst implants in outer lining of uterus Uses mother’s nutrients Continues development

26 Fetal Development Anmion Amniotic Fluid 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


28 Fetal Dev (cont’d) Umbilical Cord Blood vessels from placenta to baby
Mom’s & baby’s blood do not circulate together! Can have 2 different blood types Diffusion


30 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

31 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

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

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

34 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

35 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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