Chapter 141. 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 implantation2. after implantation, the placenta develops and begins to provide nourishment to the developing embryo. An embryo 5 weeks after fertilization is about ½ inch long.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 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 ¼ 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 ½ pounds. Most successful pregnancies last 38-42 weeks and produce a healthy infant weighing between 6 ½ and 9 pounds. 2. Critical Periods: finite periods during development in which certain events occur thatwill 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 ½ - 5 ½ weeks gestation- Ears: 3-10 weeks gestation- Eyes: 3 ½ - 7 ½ weeks gestation- Legs and Arms: 3 ½ - 7 weeks gestation- Teeth: 6- 8 weeks gestation - Palate: 6-9 weeks gestation- external genitalia: 6 ½ - 11 ½ 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 rapidcell 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-- If there is an adverse influence to the fetus during the CGP of the CNS what is the consequence for the fetus?a. Spina bifida- incomplete closure of the spine and bony encasementb. Anencephaly- upper end of the neural tube fails to close, the brain ends upmissing 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?a. Folate supplements should be taken one month after conception and continued throughout the first trimester. But due to ½ 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. 6. Define LBW and VLBW. a. LBW- A birth weight of 5 ½ 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 ½ to 8 ¾ 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 ½ 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 inpregnancy. 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 itcan 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?- Folate3. 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, andprotein 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