Similarities 2 pouches Testicles Ovaries Start out inside body Testicles “descend” before birth Fetus begins with “starter parts” that could develop into either gender.
Around 7 th Week… Baby’s body is “told” by DNA to become either male or female. “Unused” parts disintegrate “Used” parts continue development (see overhead)
Male or Female??? DNA determines baby’s gender XX = Female XY = Male Depends on which egg & sperm get together. Father determines baby’s gender.
Anatomy – similarities Function – 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!
Females Ovaries 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)oviduct
After Ovulation Egg pushed along by cilia Few days travel time to arrive in uterusuterus CervixCervix – Opening between uterus & vagina Normally tiny At birth – muscles pull open (dilation) cervix to allow baby to pass through = Labor
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
28-Day Cycle (average) Three Stages 1. Tear Down 2. Rebuild 3. Extra nutrients/blood for potential baby No Baby? Back to #1
Chemicals (hormones) Regulate events in the body Estrogen Progesterone LH (leuteinizing hormone) FSH (follicle stimulating hormone) Many others
Day 1 First menstrual blood & tissue No baby = breaks down lining of uterus 5-7 days of blood/tissue exits body Pre-Ovulation
~Day 14 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
If fertilized… Zygote begins to divide as it travels through oviduct Implants into lining of uterus
If not fertilized… Egg travels through oviduct to uterus Exits body with blood and tissues during menstruation
Birth Control Pills “Trick” body into thinking it’s pregnant Extra hormones No ovulation occurs No ovulation = no egg = no fertilization = no baby! No hormones taken for 7 days = menstruation
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 can’t get out!
Semen Contains 300-500 million sperm Sperm food pH buffers Allows sperm to survive for a couple of days inside female’s body (hostile environment)
What is sperm? Then… Used to think it was a tiny human inside each cell Spermists vs. Ovists
Now… Contains Several Parts: Head Chemical to dissolve egg goo Dad’s genetic information (DNA) Mitochondria Energy Tail Swimming
Prostate Gland Adds non-sperm stuff to semen pH buffers Nourishment Cancer very common Slower-growing (usually) Surgery for removal
Bulbourethral gland Adds lubricant to aid travel of semen through the urethra
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 female’s white blood cells Acidic environment Current
Once egg is located… Dissolve protective goo surrounding egg One gets through – enters egg Instant biochemical change in zygote No more sperm allowed in
Zygote begins developmentdevelopment Time Lapse Development
Implants in uterine lining Endometrium= outer lining of uterus Becomes placenta Uses mother’s nutrients Continues development
Fetal Development Anmion 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
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
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
Twins/Multiple Births Two types Monozygotic From one egg Identical Dizygotic From two eggs Fraternal Not identical
Identical twins One zygote Splits in 2 No one knows why! Completely random = does NOT run in families Same exact DNA Nature’s clones
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
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.