Development, CNS, PNS (Lecture #1) Flashcards
what does the embryo look like at ~3weeks after conception?
3 layered disk
what happens to the epiblast layer at ~3weeks after conception
develops a depression called the primitive groove
what happens to the primitive groove over time?
it deepens, detaches from epiblast, and closes to form neural tube
progression of neural tube closure
dorsal aspect of cervical region closes first
closure proceeds in both directions (rostrally and caudally)
rostral end closes at 24-26 days
caudal end closes at 26-28 days
when is the neural tube done forming
~4weeks after conception
what happens if the neural tube does not form correctly?
brain and spinal cord do not form correctly
skull and spine do not form correctly
what part of the neural tube becomes the brain?
rostral end
what part of the neural tube becomes the spinal cord?
everything that is not the rostral end
what happens to the rostral end of the neural tube after its closure?
starts to change shape and develops 3 major vesicles
3 major vesicles developed by rostral end of neural tube after closure
prosencephalon
mesencephalon
rhombencephalon
what does prosencephalon develop into
telencephalon (cerebral hemispheres)
diencephalon
what does the mesencephalon develop into?
midbrain
what does the rhombencephalon develop into?
metencephalon (pons & cerebellum)
mylencephalon (medulla)
parts of the central nervous system
cerebral hemispheres diencephalon midbrain pons & cerebellum medulla spinal cord
what makes up the brainstem
midbrain
pons
medulla
rostral (definition)
toward the cerebral hemispheres
caudal (definition)
toward the sacral end of the spinal cord
what is the diencephalon made up of
thalamus (largest part)
hypothalamus
epithalamus
types of glial cells
astrocyte
oligodendroglia
microglia
astrocyte
structural support and metabolism in the nervous system
oligodendroglia
produce myelin
microglia
phagocytic activity
ependymal cells
line ventrical cavities
what is myelin?
lipid-substance covering essentially all axons in CNS and some in PNS
function of myelin
insulate axons to prevent signal loss
speed transmission
myelin formed by
oligodendroglia (CNS) schwann cells (PNS)
do diseases affect myelin the same way in the CNS as in the PNS?
no
white matter
areas primarily containing myelinated axons
grey matter
areas primarily containing cell bodies
ALL synapses occur here
grey matter areas in brain
cerebral cortex
thalamus
basal ganglia
ventricles
study handout
Peripheral Nervous System contents
anything outside of brain and spinal cord
cranial nerves and ganglia
spinal nerves and dorsal root ganglia
sympathetic and parasympathetic nerves and ganglia
enteric nervous system (nerves in digestive system)
part of spinal cord that contains sensory axons
dorsal roots
part of spinal cord that contains motor and autonomic axons
ventral roots
what is the central canal filled with
fluid
which segments of the spinal cord have enlargements
cervical (for controlling UE muscles)
lumbosacral (for controlling LE muscles)
what spinal levels are associated with the sympathtic nervous system
T1-L2
what spinal levels are associated with parasympathetic nervous system
brainstem
S2-S4
fight/flight functions
pupil dilation bronchodilation cardiac acceleration inhibition of digestion piloerection stimulation of glucose release systemic vasoconstriction
rest/digest functions
pupil constriction bronchoconstriction cardiac deceleration stimulation of digestion salivation, lacrimation intestinal vasodilation
