The Biology of DevelopmentThe Biology of Development

I.I. PregnancyPregnancy

II.II. Prenatal DevelopmentPrenatal Development

III.III. Developmental HazardsDevelopmental Hazards

I.I. PregnancyPregnancy

How does a person know if she is How does a person know if she is pregnant?pregnant?

II.II. Prenatal DevelopmentPrenatal Development

-280 days, 39-40 weeks-280 days, 39-40 weeks

-3 main periods of Prenatal Development-3 main periods of Prenatal Development

-germinal-germinal

-embryonic-embryonic

-fetal-fetal

1.1. Germinal PeriodGerminal Period

1st 2 weeks1st 2 weeks Zygote created, cell divisionZygote created, cell division Zygote attaches to wallZygote attaches to wall Cell differentiationCell differentiation

Inner cells (blastocyst) grow into embryoInner cells (blastocyst) grow into embryo Outer cells (trophoblast) provide Outer cells (trophoblast) provide

nutrients/support for embryonutrients/support for embryo

Follicle releasing egg to be Follicle releasing egg to be fertilzedfertilzed

ZygoteZygote

BlastocystBlastocyst

Fetal CirculationFetal Circulation

EmbryosEmbryos

2.2. Embryonic PeriodEmbryonic Period

2- 8 weeks2- 8 weeks More cell differentiationMore cell differentiation OrganogenesisOrganogenesis 3rd week--neural tube forms, eyes, ears, nose3rd week--neural tube forms, eyes, ears, nose 24 days--heart cells24 days--heart cells 4th week-arm/leg buds4th week-arm/leg buds 6 weeks--hands6 weeks--hands 8 weeks, primitive heart beating8 weeks, primitive heart beating

Cell differentiationCell differentiation

Inner cells (endoderm) form internal body Inner cells (endoderm) form internal body parts --digestive/respiratoryparts --digestive/respiratory

Outer cells Outer cells Ectoderm (outermost)--on surface Ectoderm (outermost)--on surface

• Form nervous system, sensory, skin partsForm nervous system, sensory, skin parts Mesoderm (middle)--surrounds internal areas, Mesoderm (middle)--surrounds internal areas,

circulatory system, bones, muscles, excretory circulatory system, bones, muscles, excretory and reproductive systemand reproductive system

Life Support Of EmbryoLife Support Of Embryo

1.1. PlacentaPlacenta

2.2. Umbilical cordUmbilical cord

3.3. AmnionAmnion

Fetal CirculationFetal Circulation

3. Fetal Period3. Fetal Period

Last 7 monthsLast 7 months At 3 mos--3 inches long, weighs 1 oz., At 3 mos--3 inches long, weighs 1 oz., 5 mos--lanugo, 11 oz., 10 inches5 mos--lanugo, 11 oz., 10 inches 6 mos.--11-14 inches, 20 oz, 6 mos.--11-14 inches, 20 oz, 8-9 mos-8-9 mos-

Proximodistal and cephalocaudal Proximodistal and cephalocaudal

III. Developmental HazardsIII. Developmental Hazards

Teratology…TeratogenTeratology…Teratogen1.1. Maternal diseases and healthMaternal diseases and health

AIDS, rubella, syphilis, gonorrhea, polio, AIDS, rubella, syphilis, gonorrhea, polio, diabetes, herpesdiabetes, herpes

2.2. AgeAge3.3. NutritionNutrition4.4. RH factorRH factor5.5. Emotions/StressEmotions/Stress6.6. DrugsDrugs

DrugsDrugs harmful to Prenatal harmful to Prenatal DevelopmentDevelopment

ThalidomideThalidomide BarbituatesBarbituates AspirinAspirin Megadoses of vitaminsMegadoses of vitamins AlcoholAlcohol NicotineNicotine CaffeineCaffeine NarcoticsNarcotics LSDLSD MarijuanaMarijuana CocaineCocaine

6. Environmental hazards6. Environmental hazards

RadiationRadiation PesticidesPesticides PCBsPCBs MercuryMercury LeadLead ToxoplasmosisToxoplasmosis Hot temperaturesHot temperatures