Hd Flashcards
(27 cards)
Morphogenesis
Formation of the embryo
Dysmorphogenesis
Genetic mutation and teratogen, deformation
What are general rise factors for birth defects
Nutrition, inadequate maternal nutrition may result in premature birth and birth weight, lack of folic acid can lead to spinal bifida
Spina bifida
Spina bifida is a neural tube defect that occurs during the first month of pregnancy when the spinal column of the fetus doesn’t close completely. This can lead to damage to the nerves and spinal cord.
Risks of stress
decreases oxygen to fetus, weakens mother’s
immune system, and leads to unhealthy behaviors such as smoking or drinking alcohol
Studies show extreme maternal stress is associated with low birth weight and premature births
Mother’s Age
- Older mothers are more likely to have difficulty getting
pregnant, miscarriages, and stillbirths - Nearly 50% of pregnancies among women in their 40’s and 50’s result in miscarriage
Why does mother’s age matter?
The remaining eggs are more likely to have abnormal chromosomes. There is more DNA damage.
Pesticides
Can affect cell division, differentiation and migration. Some generate oxidative stress damaging DNA, protein and lipids. -> birth defects
What is a critical period of development
When organs are being developed, intense and rapid cell division. During this time the organ is vulnerable to toxin, viruses, and genetic abnormalities.
Brain development
Embryonic development (week 1-8)
Fetal development (week 9-birth)
Postnatal development
Birth defects
anything capable of disrupting embryonic or
fetal development and producing
malformations, usually act during a critical period. For most development – critical period for teratogenic effects is weeks 3 – 16
Teratology (main principles)
Effect depends on organism
-thalidomide: human fetus extremely sensitive; no effect on rats and rabbits
* Effect depends on genetic susceptibility
-Some are more vulnerable due to allelic variation in genes
* Effect depends on timing
-zygote period: fluids do not mix with mother’s
-embryonic period: organs are forming and especially
vulnerable
-fetal period: growth retardation and tissue damage
* Effects may be unique to some organs
* thalidomide: gross limb defects
* rubella: sensory and internal defects
* Likelihood of damage increases with usage (dose-
response-curve)
* Susceptibility is affected by the mother’s physiological
state such as her age, nutritional status, etc.
* Effects of agents on the mother might be negligible or
temporary
* Cumulative Risk: Effect may be worse if other risk factors
are present (e.g., poor nutrition, lack of medical care, other
teratogens)
toxic effects of alcoho
- Shrinking cerebellum
- Increased ventricular size
- Pancreas inflammation
Thalidomide
Drug given to mothers to prevent morning sickness duringfirst trimester
Critical period for limb formatio
Babies born without long bones of their arms and leg
Bisphenol A
- Polycarbonate plastic
- Estrogenic effects long know
- Recent regained interest in teratogenic effects (2008-2010)
- Degradation by water (leaching
Rubella
If 1st trimester pregnant women
gets rubella: 20% embryos will
get rubella infection
* results in congenital rubella
syndrome
* cardiac defects, deafness, some
cases – mental retardation
* eye anomalies
* the earlier in pregnancy the
greater malformations
* spontaneous abortion, still-born
baby
Zika
Infection (bite from infected mosquito, unsafe sex/STD with infected person) during pregnancy can cause congenital Zika syndrome
Severe microcephaly where the skull has partially collapsed
Decreased brain tissue with a specific pattern of brain damage
Damage (i.e., scarring, pigment changes) to the back of the eye: impaired visual development
Joints with limited range of motion, such as clubfoot
Environmental hazards
Radiation: high doses of radiation at work places lead to chromosomal abnormalities; prenatal death; mental retardation
Environmental pollutants and toxic wastes: such as mercury, lead and microplastics
prenatal exposure to lead affects children’s mental development
mercury poisoning (minimata disease): disorders of the CNS, small heads
Tobacco
fetal and neonatal deaths; preterm births and lower birth weights; sudden infant death syndrome (SIDS); poorer language and cognitive development at 4 years
Marijuana
growth retardation; premature birth; poorer verbal and memory development at 4 years of age
Cocaine and crack
growth retardation; spontaneous abortion; premature birth; withdrawal symptoms such as tremors and irritability
Heroin and methadone
deficient growth; SIDS; withdrawal symptoms; premature birth
Nicotine and the fetus
Nicotine constricts blood vessels
Reduces blood flow to the uterus and causes placenta to grow abnormally
Reduces the transfer of nutrients to the fetus
Nicotine raises the concentration of carbon monoxide (and decreases oxygen) in mother’s and fetus’ bloodstreams
Likely to slow fetal growth and may damage CNS
Alcohol during pregnancy?
Alcohol penetrates the placenta-fetus/embryo barrier. Alcohol kills specific cells in the developing brain. Midline structures other than the brain are affected by alcohol. Alcohol disrupts midlines in all species.
