4.outline.intro.lsu.f.09 - Chapter 4 Developing Through the...

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Chapter 4 – Developing Through the Life Span (Changes across the entire life span) Prenatal Development There are three main phases of prenatal development. The Germinal Period takes place in the first two weeks after conception and includes the creation of the zygote (fertilized egg), cell division, and the attachment of the zygote to the uterine wall. The second period is known as the Embryonic Period and occurs 2-8 weeks after conception. During this period, the rate of cell division increases, support systems for the cells form, and organs appear. The mass of cells attached to the uterine wall forms three layers and is now called the "embryo". o The inner layer of cells of the embryo is the endoderm - digestive and respiratory systems o The ectoderm (outer layer of cells) - nervous system and sensory receptors o The mesoderm (middle layer) - bones, muscles, reproductive,…etc The final period is the Fetal Period . This period begins two months after conception and lasts for seven months. During this period, the fetus is rapidly gaining weight and we see the fine detailing of the body organ and systems. Teratogens A teratogen is an agent that produces a malformation or raises the population incidence of malformation. AVOID!!! Severity of damage caused by teratogens are dependent on three factors: 1. The dose response 2. The time of exposure – certain stages of development are more vulnerable then others. 3. Genetic susceptibility - variation in maternal metabolism of a particular drug will determine what metabolites the fetus is exposed to and the duration of exposure. The genetic susceptibility of the fetus to a particular teratogenic agent will also have an effect on the final outcome.
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Fetal Alcohol Syndrome (FAS) Fetal alcohol syndrome (FAS) is a group of abnormalities in babies born to mothers who consume alcohol during pregnancy. It is the most common known non-genetic (non-inherited) cause of mental retardation in the United States. The full picture of FAS usually occurs in babies born to alcoholic mothers, or those who drink more than four to five drinks/day. However, no amount of alcohol is safe. Fetus may become addicted beginning a few hours after birth and possibly lasting till 18 months old. The following are the most common symptoms of FAS. However, each baby may experience symptoms differently. Symptoms may include: small head, small jaw, and small, flat cheeks malformed ears small eyes, poor development of optic nerve, crossed-eyes upturned nose, low bridge small upper mouth structure and teeth caved-in chest wall limited movement of finders and elbows extra fingers, abnormal palm creases incomplete or lack of development of brain structures heart murmurs, heart defects, abnormalities of large vessels incomplete development of genitalia growth, motor, and mental retardation irritability in infancy and hyperactivity in childhood poor coordination **pay attention to Facial Structure and Mental Retardation
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This note was uploaded on 05/11/2010 for the course PSYC 2000 taught by Professor Munson during the Spring '10 term at LSU.

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4.outline.intro.lsu.f.09 - Chapter 4 Developing Through the...

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