MCPHS EMBRYOLOGY - BIRTH DEFECTS EXAM QUESTIONS
AND ANSWERS WITH COMPLETE SOLUTIONS VERIFIED LATEST
UPDATE
Birth defects
Developmental disorders present at birth
Leading cause of infant mortality
Birth defects
International Classification of Diseases
Widely used guide for classifying birth defects
Classification of birth defects takes into consideration these factors
Time at onset of injury
Possible etiology
Pathogenesis
Teratology
Study of the causes, mechanisms, and patterns of abnormal development
Fundamental concept of teratology
Certain stages of embryonic development are more vulnerable to disruption than others
Belief in 1940s
,Human embryos were protected from environmental agents by their fetal membranes
Rubella virus
Could cause severe birth defects such as cataract, cardiac defects, and deafness
Time frame when rubella virus is harmful
During development of eyes, heart, and ears
Thalidomide
Limb defects - meomelia - cardiac and kidney defects
Percent of human birth defects that result from drugs, viruses, and environmental toxins
7-10%
Percent of infant deaths in North America that are from birth defects
20%
Spina bifida cystica
Vertebral defect where neural tube doesn't fuse
Occurs in 3% of neonates
Percent of birth defects detected by age 2
6%
Percent of birth defects detected by age 5
8%
3 main causes of birth defects
, Genetic
Environment
Multifactorial inheritance
Genetic factors
Chromosome abnormalities
Environmental factors
Drugs, infections, and viruses
Multifactorial inheritance
Genetic and environmental factors acting together
Percentage of neonates that have single minor defects
14%
Indication of defects of the external ears
No serious medical significance but can indicate presence of associated major defects
Presence of a single umbilical artery
Possible presence of cardiovascular and renal anomalies
Early embryos
More common to have major defects (10-15%)
Many abort spontaneously (1st-6th week)
Percentage of chromosome abnormalities in early spontaneously aborted embryos
AND ANSWERS WITH COMPLETE SOLUTIONS VERIFIED LATEST
UPDATE
Birth defects
Developmental disorders present at birth
Leading cause of infant mortality
Birth defects
International Classification of Diseases
Widely used guide for classifying birth defects
Classification of birth defects takes into consideration these factors
Time at onset of injury
Possible etiology
Pathogenesis
Teratology
Study of the causes, mechanisms, and patterns of abnormal development
Fundamental concept of teratology
Certain stages of embryonic development are more vulnerable to disruption than others
Belief in 1940s
,Human embryos were protected from environmental agents by their fetal membranes
Rubella virus
Could cause severe birth defects such as cataract, cardiac defects, and deafness
Time frame when rubella virus is harmful
During development of eyes, heart, and ears
Thalidomide
Limb defects - meomelia - cardiac and kidney defects
Percent of human birth defects that result from drugs, viruses, and environmental toxins
7-10%
Percent of infant deaths in North America that are from birth defects
20%
Spina bifida cystica
Vertebral defect where neural tube doesn't fuse
Occurs in 3% of neonates
Percent of birth defects detected by age 2
6%
Percent of birth defects detected by age 5
8%
3 main causes of birth defects
, Genetic
Environment
Multifactorial inheritance
Genetic factors
Chromosome abnormalities
Environmental factors
Drugs, infections, and viruses
Multifactorial inheritance
Genetic and environmental factors acting together
Percentage of neonates that have single minor defects
14%
Indication of defects of the external ears
No serious medical significance but can indicate presence of associated major defects
Presence of a single umbilical artery
Possible presence of cardiovascular and renal anomalies
Early embryos
More common to have major defects (10-15%)
Many abort spontaneously (1st-6th week)
Percentage of chromosome abnormalities in early spontaneously aborted embryos
