Test 2 1 Prenatal Development Child Psychology Fertilization of egg mature egg23 individual in a cells nucleus at first 23 individual in the head of Generally during 3 7 day journey of mature egg down fallopian tube to uterus 3 stages of prenatal development not referring to trimesters the sperm 1 Zygote germinal period Begins Ends fertilization conception zygote firmly implants in uterine wall 2 weeks weakly implanted Implantation tendrils from zygote penetrate uterine wall takes another week for it to hang on tighter 25 65 of zygotes survive many not all that do not survive have severe genetic defects Miscarriage zygote implants and then un implants 2 Embryo embryonic period 2nd to 8th week Begins Ends Period of most rapid cell differentiation end of 8th week bone is starting to form firm implantation Cells become different in form and function Most organs formed and crudely functioning crude movements of systems Latest developing system brain and nervous system 1st step of differentiation 3 layers form Ectoderm outer outer skin nervous system glands Mesoderm middle muscle skeleton blood Endoderm inner lungs digestive track Auxiliary structures develop changes 1 Amniotic sac contains amniotic fluid which protects from shock and temperature Old cells accumulate in fluid Amnion outer membrane of sac 2 Chorion surrounds amnion 3 Placenta outside Chorion attached to uterine lining 4 Umbilical cord connects embryo at abdomen to placenta 1 2 4 develops from zygote amniotic sac Chorion and umbilical cord 3 develops from zygote and uterus placenta Transfer of nutrients and wastes 1 Nutrients oxygen from Mom s blood build up in placenta and travel to embryo fetus via umbilical cord 2 Placenta and cord attached by semi permeable membrane like mesh What determines what can pass through and what cant SIZE big molecules CANNOT go through Test 2 2 Nutrients oxygen and wastes cross membrane Red Blood cells Infections and drugs all drugs can cross over are too big to cross Rh Blood factor Rh you have the factor in blood Baby s Rh can get into Mom s blood if Rh You do NOT have factor in blood Placenta ruptures or during some prenatal tests Causes mom to build up antibodies to fight Rh Rh factor only a problem if mom is negative and baby is positive Rh dominant Rh recessive When can you get Rh baby and Rh mom When dad is Rh Antibodies generally not problem with 1st baby 5th 8th week critical period for limb formation Critical period for limb formation 5th week already showing limbs 6 weeks hands differentiate into finger 7 weeks toes start to form Thalidomide 40s 50s now banned Greatly handicapped limb formation Commonly prescribed sedative and nausea drug Only evident if mom took it during critical period of development for limbs This drug was commonly prescribed to women during this time period Message effects of substance during pregnancy depend on nature of substance when it s used If it was taken during when the limbs were forming critical period then you found the limb defects But if it was taken before or after this period there was no effect By end of embryonic period face limbs fingers toes external genitals most internal organs crude functioning of heart liver crude movements of ingestion nervous system begins to develop Size 1 1 25 inches Less than oz 16 ounces to a pound Embryo vulnerability Most miscarriages in embryonic period Embryos vulnerable to largest of teratogens any substance that can potentially be harmful to a developing embryo or fetus Type of defects determined by when exposed to teratogen thalidomide example Effects either destruction structural defect or functional defect Embryonic defects most likely to be structural Fetal defects most likely to be functional Zygote problems most likely to lead to destruction 3 Fetus Begins start of 9th week 3rd month Ends birth Test 2 3 Summary All organs mature develop further Biggest growth period Finishing touches muscle fat growth Further formation of genitals May see gender on ultrasound by 11 12 for brain and nervous system weeks Reflexes begin 20 weeks suck hiccup swallow 22 26 weeks if born some chance of survival Age of viability previously 28 weeks After 28 weeks gains lb per week Full term 38 40 wks Preterm before 37 weeks vulnerable they will spend time in the incubator Birth normal size 7 7 lbs 20 inches 5 5 12 lbs Incubator for preterm or low birth weight Sterile environment Monitors heart and lungs which can stop Preterm low birth weight less than 5 5 lbs 1 Common causes Mother s immunities transferred at very end premature babies miss this Multiple babies twins etc mother can t support as well sharing nutrients and space Problems with uterus placenta some are genetic defects which increase the risk of preterm pregnancy Or just something goes wrong Smoking alcohol drugs account for more low birth weight than any other thing Most researches suggest that 20 30 percent of women drink while knowing that they are pregnant More low educated do this but also high educated women could do this also One reason is that they might not know they are pregnant yet If you metabolize alcohol faster than it wont stay in your system as long to effect the body High blood pressure diabetes Major stress cortisol stress hormones increase eating habits change greatly effects fetus sleeping habits change Poor health and weight extremes 2 Problems associated with preterm and low birth weight Brain and central nervous system inattention speech hearing and learning problems develop late see restlessness Respiratory system develops late allergies asthma Chemicals that are necessary for proper breathing are developed late in pregnancy so this might be affected 3 How to minimize problems Test 2 4 Physical and psychological stimulation water beds and hammocks for babies big dolls nearby that have heart beats and breathe touch and bonding fit treatment to individual be responsive read baby signals some babies are cuddlers and some don t like physical constraint Prenatal Testing CH2 she s covering what we need to know Ultrasound sound waves directed at embryo fetus echo transformed into picture Detects structural defects spina bifida bones in spine don t fuse properly around spinal cord Can be prevented from folic acid ingestion spinal column vertebrae don t properly close hydrocephalus excess of cerebral spinal fluid buildup between brain and skull so head will be larger than it should be gross defects of heart of GI track Amniocentesis remove
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