prenatal development Flashcards
down syndrome
caused by the presence of an extra copy of chromo 21 - failure to separate during meiosis
causes physical abnormalities e.g. flattened skull, short limbs & a protruding tongue
causes disabilities in motor & intellectual development
klinefelter syndrome
males have an extra X = XXY
causes undeveloped testes, enlarged breasts
impairments in language, academic, attentional & motor abilities
1/700 male births
Fragile X syndrome
results from abnormality in X chromo - becomes constricted & often breaks
causes prominent ears, long face, high-arched palate & soft skin
intellectual/learning disabilities & short attention span
more common in males
Turner syndrome
either an X is missing or part of one X is deleted in females
causes short, webbed neck, infertile
difficulty in math but verbal ability is good
1/2000 female births
Poly X
triple X pattern - XXX
normal in appearance
1/1000 female births
poly Y
triple Y pattern (YYY)
1/1000 male births
phenylketonuria (PKU)
individual cannot properly metabolize an amino acid
easily detected but if left untreated results in intellectual disability & hyperactivity
results from a recessive gene
1/10,000-20,000 births
sickle cell anemia
genetic disorder that affects RBC
occurs most often in people of African descent
recessive gene cause RBC to become ‘sickle’ shaped = cannot carry oxygen properly = body cells don’t receive enough oxygen = anemia & early death
1/500 african american children
Huntington’s disease
dominant disease that causes CNS to deteriorate
causes muscle coordination problems & mental deterioration
symptoms only appear after 35 years
1/18,000-25,000 births
germinal period / zygote stage
begins at conception & ends when zygote is implanted - first 2 weeks
creation of zygote, cell division & attachment of zygote to wall
blastocyst & trophoblast develop
what is a blastocyst
a cluster of dividing cells made by a fertilized egg
the early stage of an embryo
what is a trophoblast
the outer layer of cells that later provides nutrition & support for the embryo
the embryonic period
begins when implantation is complete - 3-8 weeks
rate of cell differentiation intensifies
organs appear
3 layers of cells form
life support system for embryo develop
what are the 3 layers of cells (embryonic period)
endoderm - inner - develops into digestive & respiratory systems
mesoderm - middle - develops into circulatory, excretory & reproductive systems system, bones and muscles
ectoderm - outer - become NS, brain, sensory receptors & skin parts
life support systems for embryo
amnion - an envelop that contains amniotic fluid in which embryo floats & provides temp & humidity controlled env
umbilical cord - contains 2 arteries & 1 vein - connects embryo to placenta
placenta - a disk-shaped group of tissues - small blood vessels from the mother & offspring intertwine but don’t join
what happens between weeks 3 - 8
week 3: neural tube forms, eyes begin to appear, heart cells differentiate
week 4: urogenital system becomes apparent, arm & leg buds emerge, 4 heart chambers, blood vessels
week 5-8: arms & legs diff further, face & facial structures, intestinal tract
the fetal period
from 2 months - birth
3 months: becomes more active, face & limbs are distinguishable & genitals identifiable
4 months: growth spurt in lower body, mom can feel movements
5 months: skin structures, more active
6 months: eyes & eyelids, hair, grasping reflex, irregular breathing
last 2 months: fatty tissues, function of organs
what is a teratogen
any agent that can potentially cause a birth defect or neg alter cog & behavioral outcomes
factors of teratogens that influence severity & type of influence
dose - greater the dose, greater the effect
genetic susceptibility - type or severity or abnormality is linked to genotype of both mother & child
time of exposure - damage caused depends on the point in development - embryonic period is more vulnerable
effects of alcohol
fetal alcohol spectrum disorders (FASD)
- body malformations e.g. defective limbs, face & heart
- learning problems & intellectual disabilities
no specific time window when alc affects baby the most - causes problems at any stage of develop
effects of nicotine
preterm births, low birth weights, fetal & neonatal deaths, respiratory problems & SIDS
ADHD
effects of meth
high infant mortality, low birth weight
developmental & behavioral problems
effects of marijuana
lower intelligence
prenatal exposure to weed linked to use at 14
effects of heroin
withdrawal symptoms e.g. tremors, irritability, abnormal crying, etc.
behavioral problems & attention deficits
sensitive period for each body part
CNS: 3-38
Heart: 3- 8
Arms: 4-8
Legs: 4-8
Ear: 4 - 16
Eyes: 4-38
Palete: 7-9
Teeth: 7-16
external Genitalia: 7-38
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