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132 Cards in this Set
- Front
- Back
The (upper, lower) limb appears in the middle of the 4th week and the (upper, lower) limb appears at the end of the 4th week
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upper, lower
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True or False, the limbs project from the dorsolateral body wall
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False, ventrolateral
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The (upper, lower) limb comes from the lower cervical region, and the (upper, lower) limb comes from the lumbosacral region
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upper, lower
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The limb bud has a core made of what tissue?
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mesenchyme
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In the mesenchymal core of the limb buds, what tissue forms connective tissue and skeleton? What tissue invades this to form muscle?
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somatic mesoderm, somitic mesoderm (myotome)
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The mesenchymal core of the limb bud is covered by what tissue?
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ectoderm
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The limb bud os shaped (generally) like what?
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a paddle
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The limb bud is elongated in the (dorsoventral, craniocaudal) axis
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craniocaudal
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The limb bud is narrow in the (dorsoventral, craniocaudal) axis
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dosroventral
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The palm or sole of the foot/hand is considered the (ventral, dorsal) surface
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ventral
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The preaxis is the (first, fifth) toe/finger and the postaxis is the (first, fifth) axis
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first, fifth
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What does AER stand for in terms of limb development?
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Apical ectodermal ridge
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The apical ectodermal ridge (AER) is a band of thickening (endoderm mesoderm, ectoderm) at the apex of the limb bud
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ectoderm
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How is the apical ectodermal ridge (AER) induced to form?
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by underlying mesenchyme
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True or False, while it does speed up the process, the apical ectodermal ridge is not required for development and growth of limb buds
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False, it IS required!
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True or False, The limb bud develops in a proximodistal direction
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True.
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The mesenchyme is located in the more (proximal, distal) end of the limb bud which puts it (close, far) from the AER
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proximal, far
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What is amelia and meromelia?
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ameloa is the absence of limb and mermelia is partial absense of limb
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Differentiation of limb bud occurs between the ___ and ___ week.
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5th, 8th
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What is a teratogen?
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An agent that can disturb the development of an ambryo
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The development of the hand and foot plated initially appears as an expansion of the (distal, proximal) part of the limb bud
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distal
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As the fingers and toes develop, what are they called?
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digital rays
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The digital rays (keep, lose) the AER and the interdigital zone (keep, lose) their AER
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keep, lose
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What process allows the interdigital zone to form?
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programmed cell death
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What is syndactyly?
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When 2 or more digits are fused together
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What three substances are expressed in the interdigital zone that lead to cell death?
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BMPs, retinoic acid receptor B, Msx-1
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True or False, when rotating, both upper and lower limbs rotate into parasagittal orientation
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True.
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The upper limb undergoes (lateral, medial) rotation and the lower limb undergoes (lateral, medial) rotation
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lateral, medial
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In the fifth week, a model of ___ begins to form that will later be replaced by bone
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cartilage
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primary centers of ossification being at the end of the ___ week
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7th
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When is the cartilage model done for upper extremeties? Lower?
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end of 6th week, mid 7th weekd
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When do secondary centers of ossification appear in epiphysis of long bones?
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after birth
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The interzonal mesenchyme forms ____ cartilage on joint surfaces of neighboring bones
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articular
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Vacuolization of mesenchyme creates what?
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synovial cavity
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The center of interzonal mesenchyme gives rise to what part of joint?
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internal structures
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What layer of interzonal mesenchyme gives rise to the joint capsule AND synovial membrane?
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outer layer
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Proper joint development depends on movement of what?
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the limbs
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Limb skeletal musculature derived from ____ mesoderm
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somitic (NOT somatic)
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The upper limbs are from (cervical, thoracic, lumbar, sacral) myotomes (pick 2)
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cervical, thoracic
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The lower limbs are from (cervical, thoracic, lumbar, sacral) myotomes (pick 2)
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lumbar, sacral
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Ventral muscle mass gives rise to (flexors, extensors), (adductors, abdutors), (pronators, supinators)
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flexors, adductors, pronators
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Dorsal muscle mass gives rise to (flexors, extensors), (adductors, abdutors), (pronators, supinators)
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extensors, abductors, supinators
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(ventral, dorsal) rami innervate hypaxial musculature
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ventral
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What are the 5 divisions of the brachial plexus?
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roots, trunks, divisions, cords, nerves
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roots of the brachial plexus come from C?-T?
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5, 1
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The equivalent to the brachial plexus for lower limbs is called what?
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lumbosacral plexus
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What are the three categories od limb development defects?
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reduction defects, duplication defects, dysplasia
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In a reduction defect, melia is (complete, partial) absence of limb and meromelia is (complete, partial) absence of limb
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complete, partial
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What is the term for having extra digits?
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polydactyly
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What is the term for the malfrmation of a limb?
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dysplasia
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What common chromosomal defect can cause limb abnormalities?
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trisomy 18
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True or False, environmental factors can cause limb abnormalities
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True.
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A clubfoot is usually caused by (trick question)
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It is multifactoral
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Amnionic band syndrome is a type of (mechanical, genetic, chemical, radiation induced) influence that causes limb amnormalities
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mechanical
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A ___ anomaly is a structural abnormality of any tpe present at birth
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congenital
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A morphological defect of an organ, part of an organ, or larger region of the body that results from an intrinsically abnormal developmental process, that is abnormal from the beginning.
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malformation
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A morphological defect that results from the breakdown of, or interference with an originally normal developmental process.
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disruption
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An abnormality that results from mechanical forces that mold a part of the fetus over a prolonged period.
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deformation
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An abnormal organization of cells into tissues and its morphological result(s); it is nonspecific and often affects several organs
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dysplasia
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A chromosomal abnormality of a gamete at fertilization is an example of
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malformation
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Exposure to teratogens can cause issues generally known as
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disruption
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oligohydramnios and clubfoot formation are known generally as
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deformation
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congenital ectodermal dysplasia is an example of what type of congenital anomaly?
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dysplasia
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Most congenital anomalies are cause by what?
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uknown etiology (50-60%)
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Mutant genes and chromosomal abnormalites each contribute to what % of human bith defects
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about 6-8% each
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things like teratogens account for what % of congenital anomalies?
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7-10%
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A combination of genetc and environmental factors account for what % of human birth defects?
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20-25%
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What are teratogens?
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agents known to cause congenital malformations
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Tissues are most sensitive to teratogens when they are done growing, or when they are growing the most?
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growing (tehcnically: proliferation and differentiation)
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From week ? To week ? Is the most sensitve period for birth defects
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3, 8
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What virus can cause cataracts, deafness, and cardiac defects?
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rubella virus
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Infection of what virus usually causes spontaneous abortion?
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Cytomegalovirus
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Infection of this virus specifically affects the nervous system and can cause mental retardation?
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Cytomegalovirus
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What type of infection is causes microcephaly, microphthalmia, and hydrocephaly? Where does this organism come from?
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Toxoplasma gondii; protozoan
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What organism causes syphilis?
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Treponema pallidum
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Treponema pallidum can cross the placenta after week ___
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20
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What antibiotic can kill the syphilis spirochetes?
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penicillin
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Thalidomide is a classic example of what type of chemical?
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teratogen
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Ethanol can cause FAS and ARND, what do these stand for?
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Fetal alcohol syndrom and alcohol-related neurodevelopmental disorder
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FAS and ARND together have an incidence of 1 in every ? Live births
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100
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What is thought to be the most common cause of mental retardation?
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maternal alcohol abuse
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What can result in intrauterine growth retardation?
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cigarette smoking
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Androgenic agents like synthetic progestins were used to prevent abortions, but what is their downside?
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masculinization of female external genitalia in female embryos
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In the 4th to 10th month of pregnancy what can cause tooth defects?
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tetracycline
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Streptomycin is associated with damage to what CN?
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8th
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What drug for acne has a high rate of spontaneous abortion, cardiovascular, and neural tube defects?
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retinoic acid
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Antiocoagulants like warfarin can cause what two things?
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chondrodysplasia, microcephaly
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What type of drug is associated with facial defects, cleft palate, heart defects, neural tube decefts, urogenital and skeletal abnormalities?
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anticonvulsants
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Diphenylhydantoin, valproic acid, and trimethadione are all examples of what?
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anticonvulsants
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Chemotherapeutic agents are highly teratogenic because they inhibit what process?
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mitosis in rapidly dividing cells
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Cocaine is associated with spontaneous abortion, prematurity, and what two other things?
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microcephaly and neurobehavioral disturbances
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Low birth weight and CNS dysfunction are associated with what drugs?
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heroin and methadone
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True or False, radiation tends to cause limb defects
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False, it can cause almost any defect, not just limbs
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What three things are particularly sensitive to radiation damage?
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CNS, palate, skeletal system
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What problems restricts mobility of the fetus, causing prolonged compression in an abnormal posture?
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oligohydramnios
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True or False, olighydramnios causes dislocation of hip and clubfoot
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True.
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Polyploidy is a dupication of (half, whole) set of chromosomes
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whole
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someone with triploidy will have how many chromosomes?
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69
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Someone with 92 chromosomes is said to be
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tetraploidy
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Lack of cleavage during first mitosis can cause what genetic issue?
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tetraploidy
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2 sperm in the same oocyte, or failure of 2nd polar body to separate from secondary oocyte can cause what
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triploidy
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The principle cause of aneuploidy is ___ during meiosis
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nondisjunction
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What is it called when you deviate from the normal diploid number, either too few or too many?
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aneuploidy
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The frequency of aneuploidy (increases, decreases) with increased maternal age
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increases
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Having 45 chromosomes is called
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monosomy
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What is the most common cytoenetic abnormality found in spontaneous abortions?
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monosomy
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Live birth autosomal monosomy is (common, rare)
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rare
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Sex chromosomal monosomy produces what? What is the sex chromosome pair?
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Turner's, XO
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Turner's syndrome usually happens from nondisjunction in (sperm, egg)
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sperm
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Having 47 chromosomes is called
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trisomy
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True or False, those with XXX sex chromosomal trisomy have a normal appearance
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True.
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Nondisjunction in meiosis II of spermatogenesis causes what combination of sex chromosomes? (hint: 3)
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XYY
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Klinefelter's syndrome has what sex chromosomes?
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XXY
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Klinefelter's syndrome is usually not noticed until when?
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puberty
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XXY can result in (long, short) legs
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long
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Trisomy 21 is also known as ___ syndrome
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Down's
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An individual with 2 or more genotypes is called what?
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mosaicism
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How quickly do those with trisomy 18 and 13 usually die?
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within a year
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Majority of chromosomal breaks are caused by what type of factors? (very general)
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environmental
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cri du chat is the partial deletion of the short arm of chromosome #?
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5
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The transfer of piece of chromosome to non-homologous chromosome
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translocation
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Reversal of chromosome segment
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inversion
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Duplicate portion of chromosome
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duplication
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When the centromere divides transversely, it is called what?
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isochromosome
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Autosomal (dominant, recessive) diseases are only manifested when the genes are homozygous
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recessive
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The process of removing amnionic fluid with a needle is called
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amniocentesis
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With amniocentesi, you look for ___ with a neural tube defect and ___ for hemolytic deiseases
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alpha-fetoprotein; bilirubin
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Chorionic villous sampling can be done as early as ? Weeks after fertilization
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7
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True of False, Amniocentesis detects earlier than Chorionic villous sampling
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False, the other one is earlier
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What technique lets you visualize the chorionic sac?
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ultrasound
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The biparietal diameter of the ___ helps estimate fetal age?
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skull
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True or False, an ultrasound does not allow for detection of hydrocephaly
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False, it can
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