Fetal Development

___ chromosomes are organized into ___ pairs

46, 23

of the chromosome pairs, 22 are termed __________

autosomes

the 23rd pair of chromosomes consists of what

the X and Y sex chromosomes

trisomy

additional chromosome (47)

monosomy

deletion (45)

how do numerical abnormalities happen

error occurring during early cell division, specifically a meiotic error during gametogenesis; not hereditary

most common form of a trisomy

down syndrome

down syndrome is a trisomy of which chromosome

21st

klinefelter syndrome presentation

male produces inadequate testosterone and has impairments in developing secondary male sexual characteristics

numerical abnormality of klinefelter syndome

47XXY

trisomys 13 and 18

rare but involve significant limitation in activities and participation secondary to profound intellectual disability and impaired body function and structure

________ is usually not consistent with life

monosomy

what syndrome is from monosomy that does not cause death

turner syndrome

turner syndrome

affects girls who will have a short stature, webbed neck; 20% have obstruction of left side of heart; normal intellectual function but may have vision-perceptual impairments

cystic fibrosis

disorder of endocrine glands leading to pancreatic insufficiency, hyperplasia of mucus producing cells in lungs, and excessive electrolyte secretion of sweat glands

numerical abnormality of duchenne muscular dystrophy

x linked deletion of the dystrophin gene, males, Xp21

dechenne muscular dystrophy

intrinsic muscle disease, creatine kinase elevated and dystrophin absent; leads to progressive intrinsic muscle weakness from proximal to distal

numerical abnormality of neurofibromatosis

autosomal dominant with variable expression (mutation of gene of chromosome 17 or 22)

neurofibromatosis

nerve tumors, frequently in CNS and skeletal system; associated complications include glaucoma, scoliosis, HTN, ADHS, verbal and nonverbal learning disabilities

numerical abnormality with osteogenesis imperfecta

autosomal dominant; 19 different genes associated

osteogenesis imperfecta

connective tissue disorder, problem with collagen development; short stature, multiple fractures of long bones, kyphosis, scoliosis; adolescent onset hearing loss

numerical abnormality with spinal muscular atrophy

autosomal recessive, mutation of SMN gene on 5th chromosome

spinal muscular atrophy

anterior horn cell degeneration and flaccid paralysis; proximal muscle weakness, respiratory problems, potential feeding problems

translocation

transfer of a portion of one chromosome to another; common dysfunction

inversion

chromosome breaks in two places and then reattaches in the reverse order; or ring chromosome when deletions occur at both tips of a chromosome and the ends stick together

cri-du-chat syndrome

unusual facial appearance, high pitched cry, intellectual disability

abnormality of cri-du-chat

portion of the short arm of chromosome 5 is missing

mosaicism

typical features of down syndrome but not the common physical or intellectual impairments

abnormality of mosaicism

cells in the same individual having different genetic makeups

autosomal dominant inheritance

one parent provides mutant gene, 50% risk of offspring inheriting disorder

autosomal recessive inheritance

must inherit abnormal gene from both parents, parents will not have disorder, 25% chance child will inherit

common autosomal recessive disorder

cystic fibrosis

x linked disorders

generally affect male offspring, caused by single abnormal recessive gene, 50% of males will have disorder

examples of x linked disorders

rett syndrome, hemophilia, dechenne muscular dystrophy, fragile x syndrome

when do the heart and major blood vessels develop

16 days after fertilization

most other organs begin forming at about...

5 weeks

organs are completely formed by

12 weeks, except brain and SC

when do most congenital malformations occur

during the period when organs are forming, embryo most vulnerable

at 5 weeks

neural tube and major organ systems begin to develop

at 6 weeks

heart muscle tissue develops, heart begins to beat, buds develop that will become arms and legs

at 7 weeks

heart chambers form, blood starts to flow through major blood vessels

at 8 weeks

lungs, digestive system, and kidneys develop; hands and feet begin to form

at 9 weeks

major organ systems continue to develop, bones develop and begin to harden, elbows and toes form

at 10 weeks

intestines rotate, kidneys begin to function, embryo begins to urinate; umbilical cord is fully developed, blood vessels pass through cord from embryo to placenta villi

at 11-13 weeks

all major organ systems have formed but continue to grow and develop; liver and spleen begin making RBCs and platelets; fetus starts to open/close hands and mouth

at 14-15 weeks

fetus starts to move

at 16-18 weeks

fetus moves more vigorously, mother is able to feel the movement

at 25-27 weeks

fetus is active, changing positions often; air sacs begin to form in lungs

at 28-29 weeks

lungs may be developed enough to breathe air

at 30-36 weeks

brain and nervous system become fully developed; major organ systems are mature but continue to grow/develop; fetus starts to practice breathing with amniotic fluid

at 37-42 weeks

labor and delivery

during fetal development, the UE and LE rotate...

in opposite directions

in early stages of fetal development, both UE and LE project ______ from the body

laterally

adduction of arm and leg buds begins at what weeks

7-8

at the end of week __, the fetal position has been achieved

8

UE buds rotate medially or laterally

laterally

LE buds rotate medially or laterally

medially

knees flex in the same or opposite direction from the elbow

opposite

multifactorial disorders examples

diabetes, obesity, heart disease, myelomeningocele

multifactorial disorders

interaction of heredity and environment

mitochondrial inheritance example

MELAS/SLE

teratogens definition

environmental agents that affect fetal development

environmental factors

physiological wellbeing of mother, environment provided by parents, nutrition, prenatal care, avoid threats to fetus, adequate weight gain, physically active, cease tobacco/alcohol/caffeine/drug use

what parts of the body do fetal alcohol spectrum disorders affect

structural malformations and CNS dysfunction, results in structural brain damage; deficits in memory and information processing

deficits of child with a fetal alcohol spectrum disorder

learning, intellectual, social skills, attention, motor skills, executive functioning, behavioral, mental health, sensory processing

1/____ live births are fetal alcohol spectrum disorders

100

LBW infants

birth weight < 2500g/5.5lb

VLBW infants

birth weight < 1500g/3.5lb

small for gestational age is classified as

below the 10th percentile for gestational age

causes of LBW or SGA

maternal illness, smoking, malnutrition; assisted reproduction methods, multiple gestation births, adolescent mothers, hx

when does the head first move towards the body, followed by startle

8-9 weeks gestation

when are isolated limb movements seen with the simultaneous onset of arm and leg movements

after 9 weeks

when do hand to face contact and various head movements begin

after 10 weeks

when is opening of the jaw seen, along with bending on the head and stretching movements

11 weeks

when do breathing movements occur

12 weeks

when are 2/3 of the fetus's arm movements directed toward objects in the uterus

12 weeks

during what trimester is arm movement the most active, followed by leg movement

second

during which trimester is mouth and trunk movement the least active

second

which trimester has decreased generalized movements

third

4D ultrasound can provide more detailed viewing of fetal movements ___ weeks earlier compared to 2D

2

__ weeks gestation for trunk movement

8

__ weeks gestation for individual limb movement

9

neurological and developmental abnormalities that can be detected on fetal ultrasoun

spina bifida, anencephaly, down syndrome

diagnostic ultrasound can be performed as long as the _________ _________ is still open

anterior fontanelle (4-24 months)

what to look for during cranial ultrasound in neonates and children

structural abnormalities of hemispheres, cerebellum, brainstem; periventricular leukomalacia, necrosis, and scar formation with cysts in white matter adjacent to ventricles; blockage of CSF flow, resulting hydrocephalus, and degree of intraventricular hemorrhage - motor function