Development of PNS Flashcards
What is the first marker of human brain segmentation?
mesencephalic flexure
tripartite brain =
prosencephalon (forebrain)
mesencephalon (midbrain)
rhombencephalon (hindbrain)
in the adult the lumbar spin ends at
L2-L3
where would a needle to make a spinal tap be inserted?
in L4-L5
Tethered Cord Syndrome
spinal cord is attached to connective tissues within the column. causes abnormal stretching of the spinal cord. it is a progressive disorder.
Biopotential progenitor cells arise from the ___ plate
alar
Biopotential progenitor cells form
glial lineage progenitor cells which produce cells supporting the CNS, and neuronal lineage progenitor cells which produce neurons.
The Marginal Layer
Spinal Ganglion
Marginal Layer
contains neuronal processes
Biopotential progenitor cells form…
neurons and neuroglia
so, neurons, astrocytes, oligodendrocytes
ependymal cells
Neurons and neuroglial cells go to the
cortical plate
Stages of a neuroblast include
apolar neuroblast —> bipolar neuralblast –> multipolar neuropolar neuralblast
Where does neuroblast differtentiation into their final form (neurons) occur?
in the mantle layer
what happens to a postmitotic neuron/glial cell?
the neurons/glial cells migrate outward to form the intermediate mantle or cortical zone, which becomes the grey matter
intermediate mantle =
the cortical zone
neuronal processes move out to surround
developing grey matter and form outer white matter
marginal zone =
white matter
Mantle vs cortical vs marginal
mantle and cortical = grey matter, marginal zone = white matter
BMP4/7 secreted in ectoderm establish
signaling center in the roof plate
BMP4 in the roof plate upregulates
TGF-beta proteins, including BMP5 and BMP7, activin and dorsalin
SHH from notochord establishes additional SHH signaling in floor plate
a protein gradient consisting of _______ proteins and ______ activate transcription factors that regulate neuronal differentiation
TGF-beta and SHH
TGF-beta controls
PAX-3/7 which upregulates sensory neuron differentiation
PAX-3/7 controls
sensory neuron differentiation
SHH activate
PAX6 and ventral (motor) neuron differentiation
ventral neurons will be differentiated by
PAX-6
dorsal neurons will be differentiated by
PAX-3/7
Shh from the ____—> Pax __
notochord and floor plate, Pax-6
TGF-betas (BMP) from the ____ —> Pax ____
dorsal neural tube, Pax-3/7
a high concentration of Pax-3/7 will favor
sensory neuron development
a high concentration of Pax-6 will favor
motor neuron development
Dorsal area —>
sensory input, Afferent
Ventral area –>
motor input, Efferent
Neural crest —>
dorsal root ganglia, chain ganglia (motor)
, chromaffin cells of adrenal medulla, preaortic ganglia (motor)
parasympathetic ganglia in walls of viscera
Ganglia formed by neural crest
motor/efferent
autonomic
sympathetic
chain ganglia (paravertebral) and pre-aortic ganglia
parasympathetic (within walls of viscera)
Sensory/afferent
Dorsal root ganglia
Input into dorsal horn
CNS vs PNS derived from?
CNS– neural tube
PNS - neural crest
PNS =
somatic autonomic (sympathetic+parasympathetic)
PNS components
peripheral ganglia and nerve endings
cranial nerves- 12
spinal nerves -31
Somatic nervous system
conscious action
ANS
unconscious action+ maintains homeostasis
Where would general visceral efferent neurons be located in the spinal cord?
the intermediate grey matter, although they must pass through the ventral horn
they’re ONLY located between T1-L2 and S1-S4
T1-L2
sympathetics, cell bodies located in the lateral grey area
S1-S4
parasympathetics, cell bodies located in the lateral grey area
how many spinal nerves are there
31
what kind of information do spinal nerves carry?
mixed
what kind of information do dorsal/ventral ramus carry?
mixed
SCN9A
sodium channel located in the disorder “congenital insensitivity to pain”
of neurons in path from CNS
two neurons
Somatic has ___ neuron in its path
one
how many neurons in the ANS?
two: preganglionic and postganglionic
sympathetic is the
stimulatory, fight or flight
parasympathetic is the
rest digest system
the Alar plate –>
becomes the DRG
dorsolateral thickening of the intermediate zone of the neural tube
gives rise to sensory neuroblasts of the dorsal horn
receives axons from dorsal root ganglia, which endter spinal cord and become dorsal (sensory roots)
the Basal plate
ventrolateral thickening of the intermediate zone of the neural tube
gives rise to motor neuroblasts of the ventral and lateral horns
projects axons from motor neuroblasts, which exit spinal cord and become ventral motor roots
basal plate eventually becomes the ventral horn of the spinal cord
Shh induces formation of
motor neurons
Neuroepithelium
refers to initial epithelial layer of neural tube
biopotential progenitor cells
refers to a cell that has been restricted to one of two pathways: neuronal lineage or glial lineage
early Neural tube epithelia
pseudostratified epithelium
