embryologic development Flashcards
otocyte
egg
mitosis
cell division
gastrulation
creation of the germ layers
-all growth is the result of cell division of preexisiting cells
3 germ layers
ectoderm, mesoderm, endoderm
ectoderm
outer skin layers, nervous system and sense organs
-early neural groove leads to entire CN
-the part that gets pinched off from the outside becomes the nervous system and CNS
mesoderm
skeletal structures, circulatory structures, meninges, notochord, reproductive organs and cartilage
-including ossicles and temporal bone
-in between two other germ layers
endoderm
digestive canal and respiratory organs (viscera)
-including middle ear, mastoid cavities, and ET
-most internal
neurulation
neural tube development
-within third week the ectoderm thickens to form the neural plalte
-fold inward forming a groove at midline with a fold on both sides
-neural folds begin to fuse midway along the groove which forms the tube
-fusion occurs along the tube (zipper action)
-then the tube separates from the surface ectoderm and is enclosed inside the body
spina bifida
failure of the caudal neuralpore to close
-vertebrae does not form over the spinal cord
-more route for infection
crania bifida
failure of the rostral neuropore (end of neural tube) to close
-central cavity is exposed
-not conductive to postnatal life
notochord
lies outside of the neural tube near the ventral surface and is the precursor for the skeletal axis, helping to form the vertebral column
crest cells
what is left behind by each neural fold
-forms sensory neurons of the dorsal root ganglia, some CN, postganglionic neurons of the autonomic nervous system, and schwann cells of the PNS
sulcus limitans
longitudinal groove in the lateral wall of the neural tube, separating the dorsal/alar half from the ventral/basal half in the future spinal cord and brainstem
ventral/basal division
anterior (ventral) horns in gray matter with somatic and autonomic motor neuron cell bodies
dorsal/alar division
posterior dorsal horns in the gray matter with ascending pathway cells
flexures of neural tube
cervical, cephalic, and pontine
cervical flexure
where future brainstem meets future spinal cord
-straightens out through development
cephalic flexure
at the level of the future midbrain and remains as the bend between the axis of the brainstem and the axis of the cerebrum in the adult CNS
-making a T shape meeting point
pontine flexure
on the posterior/dorsal surface in the area of the pons and 4th ventricle
secondary vesicles
encephalon, diencephalon, metencephalon, and myelencephalon
telencephalon
cerebrum/cerebral hemispheres
-lateral ventricles
-comes off the prosencephalon (primary vesicle)
diencephalon
thalamus (and hypothalamus and surrounding)
-third ventricle
-comes off the prosencephalon (primary vesicle)
mesencephalon
midbrain
-forms cerebral aqueduct
metencephalon
cerebellum and pons
-part of 4th ventricle
-comes off the rhombencephalon (primary vesicle)
myelencephalon
medulla
-part of 4th ventricle and central canal
-comes off the rhombencephalon (primary vesicle)
monogenic deficits
single mutant gene, mendelian inheritance pattern
multifactorial deficits
mendelian inheritance pattern, exogenous environmental factors
-multiple things caused it
mitochondrial deficits
alteration in mitochondrial DNA, nonmendelian
-mainly maternal transmission
-affects enzymes of mitochondria
nonmendelian chromosomal aberrations
excess, lack or structural alteration of one or more of the 23 pairs of chromosomes
-i.e. down syndrome
what ways can infants be assessed for abnormal functions
monitoring of infants
-respiration
-control of body temp
-regulation of thirst and appetite
-rooting
-sucking, swallowing and grasping
-movements and postures of neck, trunk, and limbs
tay-sachs disease
lysosomal storage disease
-inability to break down ganglioside which accumulates in neurons causing them to swell or burst
niemann-pick disease
autosomal recessive inheritance
-inability to break down sphingomyelinase which accumulates in neurons causing them to swell and burst
what do the germ layers become in AVS
ectoderm : outer and inner ear, membranous labyrinth
mesoderm : ossicles, temporal bone, and bony labyrinth
endoderm : middle ear epithelial lining, mastoid cavities and eustachian tube
branchial/pharyngeal arch structures
arches - external humps
clefts/grooves - external
pouches - internal
membrane - point of contact of the groove and pouch
what do the archs become
first arch - rise to CN 5
second arch - rise to CN 7
third arch - rise to CN 4
fourth arch - rise to CN 10
sixth arch - rise to CN 11
