Chapter 14 1 Stages of Embryonic and Fetal Development 1 an newly fertilized ovum is about the size of a period at the end of a sentence This Zygote at less than one week after fertilization is not much bigger and is ready for implantation 2 after implantation the placenta develops and begins to provide nourishment to the developing embryo An embryo 5 weeks after fertilization is about inch 3 a fetus after 11 weeks of development is just over an inch long The umbilical cord and blood vessels connecting the fetus 4 A newborn infant after nine months of development measures close to 20 inches in length from 8 weeks to term this infant grew 20 times longer and 50 times long heavier NOTES Describe the stages of both embryonic and fetal development During fetal development what organs are first to reach maturity The embryo develops at an amazing rate At first the number of cells in the embryo doubles approximately every 24 hours later the rate slows and only doubling occurs during the final 10 weeks of pregnancy At 8 weeks the 1 inch embryo has a complete CNS a beating heart a digestive system well defined fingers and toes and the beginnings of facial features The fetus continues to grow during the next 7 months Each organ grows to maturity according to its own schedule with greater intensity at some times than at others Weight increases from less than an ounce to about 7 pounds Most successful pregnancies last 38 42 weeks and produce a healthy infant weighing between 6 and 9 pounds 2 Critical Periods finite periods during development in which certain events occur that will have irreversible effects on later development stages usually a period of rapid cell growth Critical period for neural Tube development is from 17 30 days gestation Central Nervous System 2 6 weeks gestation Heart 2 5 weeks gestation Ears 3 10 weeks gestation Eyes 3 7 weeks gestation Legs and Arms 3 7 weeks gestation Teeth 6 8 weeks gestation Palate 6 9 weeks gestation external genitalia 6 11 weeks gestation 3 Anencephaly an uncommon and always fatal type of neural tube defect characterized by the absence of a brain 4 Spine Bifida one of the most common types of neural tube defects characterized by the incomplete closure of the spinal cord and its bony encasement 5 How to prevent Neural Tube defect Folate supplements taken 1 month prior to conception and continued throughout the first trimester Women who have had a child with neural tube defect prior to this pregnancy must consult a doctor and may be given doses ten times larger than the average woman 4 miligrams daily most prenatal vitamins contain at least 800micrograms And grain products contain folate for those who do not plan or suspect their pregnancy from NOTES 1 Define critical growth period a finite periods during development in which certain events occur that will have irreversible effects on later development stages usually a period of rapid cell division When is the CGP of the central nervous system of the fetus a 2 6 week period What organs grow out of the neural tube a Brain and spine consequence for the fetus If there is an adverse influence to the fetus during the CGP of the CNS what is the a Spina bifida incomplete closure of the spine and bony encasement b Anencephaly upper end of the neural tube fails to close the brain ends up missing or fails to develop often ends in miscarriage infants born die shortly after birth What advice would you give a woman who wants to get pregnant regarding nutrient intake related to a healthy CNS of her infant Which nutrient and when should it be started 6 Define LBW and VLBW a Folate supplements should be taken one month after conception and continued throughout the first trimester But due to of the pregnancies in the U S A are unplanned it makes it difficult to detect neural tube defects early So grain products in the U S A are now fortified with folate to insure adequate intake a LBW A birth weight of 5 pounds 2500g or less indicates probable poor health in mother during pregnancy before pregnancy or both Normal birth weight for a full term baby is 6 to 8 pound about 3000 4000 g Greater chance of having physical and mental birth defects contracting diseases and dying early in life 2 3 of infants that die before their first birthday are LBW newborns b VLBW are 3 pounds or less Struggle for immediate health and survival and also for future cognitive development and abilities 7 Nutrients NEEDED IN PREGNANCY notes 2 Discuss the specific changes of the macronutrients energy protein and fat needs in pregnancy a Energy is needed more in pregnant women They need an additional 340 kcalories per day during the second trimester and an additional 450 kcalories during the third trimester Foods to help get extra kcals whole grain breads and cereals legumes vergetables citrus fruits and milk products b Protein an additional 25 grams per day for women who are pregnant Foods meats milk products protein containing plant foods legumes whole grains nuts High protein supplements are discouraged to pregnant women because it can be harmful to the infant s development c Fats essential long chain polyunsaturated fatty acids are important to the growth and development of the fetus The brain depends on omega 3 and omega 6 for its growth function and structure Food vegetable oils meats poultry eggs nuts seeds and vegetables What other nutrients are required in additional amounts in pregnancy a Folate B vitamins to activate Folate enzyme vitamin B12 Iron Zinc Vitamin D Calcium Phosphorus Magnesium Fluoride What nutrients are most difficult to meet during pregnancy a Iron and Zinc Which nutrients show a dramatic increase in absorption Folate 3 8 Define and discuss both preeclampsia and eclampsia What are the signs and symptoms of each What are the consequences for mother and infant if these conditions are left untreated a Preeclampsia A condition characterized by hypertension fluid retension and protein in the urine formerly known as pregnancy induced hypertension Generally occur with first pregnancy The edema is a while body edema distinct from the localized fluid retention women normally experience in late pregnancy Cause unclear Most often occur after 20 weeks gestation Symptoms usually regress within two days of delivery Both men and women who were born out of pregnancies with preeclampsia are more likely to have a child born with preeclampsia complications suggesting genetic predisposition Affects almost all of the mothers organs