Ch 4 developmental - Ch 4 Study Notes PDF

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Ch. 4 Prenatal Development Key Terms Prenatal Development - Development that occurs between the moment of conception and the beginning of the birth process Period of the Zygote (germinal period) - First phase of prenatal development, lasting from conception until the developing organism becomes firmly attached to the wall of the uterus. Period of the Embryo - Second phase of the prenatal development, lasting from the third through the eighth prenatal week, during which the major organs and anatomical structures take shape. Period of the Fetus - Third phase of prenatal development, lasting from the ninth prenatal week until birth; during this period, all major organ systems begin to function and the fetus grows rapidly. Blastocyst - Name given to the ball of cells formed when the fertilized eggs first begins to divide. Embryo - Name given to the prenatal organism from the third through eighth week after conception. Implantation - The burrowing of the blastocyst into the lining of the uterus. Amnion - A watertight membrane that surrounds the developing embryo, serving to regulate its temperature and to cushion it against injuries. Chorion - A membrane that, as above becomes attached to the uterine tissues to gather nourishment for the embryo. Placenta - An organ formed from the lining of the uterus and the chorion, that provides the respiration and nourishment of the unborn child and the elimination of its metabolic wastes. Umbilical Cord - A soft tube containing blood vessels that connects the embryo to the placenta. Neural Tube - The primitive spinal cord that develops from the ectoderm and becomes the central nervous system. Fetus - Name given to the prenatal organism from the ninth week of pregnancy until birth. Vernix - White, cheesy substance that covers the fetus to protect the skin from chapping. Lanugo - Fine hair covering the fetus’s body that helps vernix stick to the skin.

Age of Viability - A point between the 22nd and 28th prenatal weeks when survival outside the uterus is possible. Teratogens - External agents such as viruses, drugs, chemicals and radiation, that can harm a developing embryo or fetus. Sensitive Period - A period during which an organism is most susceptible to certain environmental influences; outside this period, the same environmental influences must be much stronger to produce comparable effects. Rubella - A disease that has little effect on a mother but may cause a number of serious birth defects in unborn children who are exposed in the first 3-4 months of pregnancy. Toxoplasmosis - A disease caused by a parasite found in raw meat and cat feces; can cause birth defects if transmited to an embryo in the first trimester and a miscarriage later in pregancy. Syphilis - A common sexually transmitted disease that may cross the placental barrier in the middle and later stages of pregnancy, causing miscarriage or serious birth defects. Genital Herpes - a sexually transmitted disease that can infect infants at birth, causing blindness, brain damage, or even death if not diagnosed and treated. Acquired Immune Deficiency Syndrome(AIDS) - A viral disease that can be transmitted from a mother to her fetus or newborn and that results in a weakening of the bodys immune system, and ultimately death. Thalidomide - A mild tranquilizer that, taken early in pregnancy can produce a variety of malformations of the limbs, eyes, ears and heart of the baby. Diethylstilbestrol (DES) - A synthetic hormone, formerly prescribed to prevent miscarriage that can produce cervical cancer in adolecent femal offspring and genital tract abnormalities in males. Fetal Alcohol Spectrum Disorder (FASD) - Term used to describe the full range of congenital problems commonly observed in the offspring of mothers who consumed alcohol during pregnancy. Cleft Lip - A congenital disorder in which the upper lip has a vertical or pair of vertical opening or groove. Cleft Palate - A congenital disorder in which the roof of the mouth does not close properly during embryonic development, resulting in an opening or groove in the roof of the mouth. Folate - B Complex vitamin that helps to prevent defects of the central nervous system.

Folic Acid - Synthetic version of folate. Spina Bifida - A bulging of the spinal cord through a gap in the spinal column. Anencephaly - a birth defect in which the brain and neural tube fail to develop or develop incompletely and the skull does not close. Neonate - A newborn infant from birth to approximately 1 month old.

Concept Check 4.1 1. Which of the following events marks the transition between when we label the developing organism a zygote to when we begin to label it an embryo? a. conception b. ovulation c. implantation d. cell division 2. Which organ is responsible for the transmission of nutrients and wastes between the developing organism and the pregnant woman? a. amnion b. placenta c. chorion d. embryonic disk 3. What is the most critical period in prenatal development for potential damage to the developing organism from teratogens? a. the period of the embryo b. the period of the zygote c. the period of the fetus d. the period of the blastocyst 4. Rubella - Blindness, deafness, intellectual disability 5. Toxoplasmosis - Eye and brain damage; late- pregnancy miscarriage 6. Thalidomide - Missing or malformed arms and legs 7. When a pregnant woman drinks alcohol during her

pregnancy, she risks having a child born with - Fetal alcohol spectrum disorder (FASD) 8. Teratogens are external factors such as Drugs ; Disease or chemicals that harm the developing organism. 9. Sexual differentiation begins when a gene on the Y chromosome instructs the Indifferent Gonad to produce testes if the developing organism is a male. 10. Erica was born in 1960 and she appeared at birth to be a normal, healthy girl. Her life proceeded normally until she turned 20. Then she discovered that she had a rare form of reproductive organ cancer and that she would be unlikely to be able to have children herself. Her doctor wondered whether her mother had taken Diethylstilbestrol (DES) during her pregnancy with Erica. He suspected that the drug could have been a teratogen that caused Erica’s reproductive abnormalities....