nervous sys histo (reynolds) Flashcards
formation of neural tube
- neural plate thickens 2. neural plate elongates 3. lateral folding 4. fusion of neural folds and separation from ectoderm (NCC)
3 segmented brain
prosencephalon (forebrain), mesencephalon (midbrain), rohmbencephalon (hindbrain)
5 segmented brain
telencephalon, diencephalon, mesencephalon, metencephalon, myelencephalon
structures from the telencephalon
cerebral hemispheres (cerebrum), (lateral ventricles)
structures from the diencephalon
thalamus, hypothalamus, pituitary, pineal body, eyes, (3rd ventricle)
structures from the mesencephalon
anterior (visual) and posterior (audio) colliculi, cerebral aquaduct
structures from the metenencephalon
cerebellum, pons
structures from the myelencephalon
medulla oblongata
histology in proliferating neural tube
pseudostratified epithelium, where DNA synthesis is happening in the external limiting membrane and mitosis is happening in the lumen
neuronal lineage progenitor cell
mature neuron or microglial cell
glial lineage progenitor cell
oligodendrocyte, type 2 astrocyte, type 1, astorcyte, special glial cells, ependymal cells
briefly describe the cell lineage in the CNS
start at neuroepithelium in the neural tube which can turn into a multipotential stem cell, then bipolar progenitor cell, then into neuronal or glial lineage progenitor cell
how do axons and dendrites form?
during neurite outgrowth, growth cones with numerous filopodia will extend and contract, testing the local enviornment
holoprosencephaly
developmental defect when the ventral forebrain is not induced, cyclopia
hydrocephaly
developmental defect when the cerebral aqueduct is block and there is a build up of water on the brain
what does the pons do?
relay signals linking the spinal cord and the cerebral cortex with the cerebellum
what does the cerebellum do?
center for balance and posture
what does the medulla oblongata do?
relay center between the spinal cord and the higher brain centers and regulates respiration, heartbeat, reflex movements
formation of peripheral nerves
- outgrowth of axons from motor neurons in the basal plate 2. NCC form spinal ganglion 3. interneurons form between sensory neuron termination and motor neurons 4. reflex arc is formed
t/f. NCC form all sympathetic and parasympathetic ganglia
true.
hirschsprungs disease
a lack of colonization of NCCs in wall of lower colon, so theres a lack of parasympathetic innervation and no peristalsis.
symptoms - complete constipation in newborns
schwann cells
NCC derivatives that wrap around the nerve process like a jelly roll
carcot-marie-tooth
demyelinating polyneuropathy where there is slowed nerve conduction. No cure.
t/f. there is a lot of myelin in neurites.
false. there is a lot of actin in neurites (cytoplasmic outgrowths that will become an axon or dendrite)
environmental influences for neurite outgrowth
chemoattraction, chemo repulsion, contact attraction, contact repulsion
fascicles
bundles of axons
stabilization of axons
interaction between neuron and target structure; influence connection type and number
mechanism of stabilization
apoptosis to eliminate axons that don’t reach the normal target and connection errors, and to reduce the size of neuronal pool to match target or presynaptic input
what is epithelial mesenchymal transition (EMT)?
when NCC slowly lose thier epithelial characteristics like gap junctions, cell adhesion, and become mobile, non polar, and gain integrins
3 divisions of NCCs
cranial, circumpharyngeal, trunk
what do cranial NCCs form?
tissues of the face
what do circumpharyngeal
NCCs form?
vagal and cardiac crest cells
precursors to parasympathetic innervation
vagal crest cells
what is the most diverse division of NCC that leave after the NT closes?
trunk NCC
3 pathways of trunk NCC
dorsolateral, ventrolateral, ventral
dorsolateral cells
melanocytes
ventrolateral cells
sensory ganglia
ventral cells
sympathoadrenal (chromaffin cells, sympathetic ganglia and neurons)
albinism
neurocristopathy with pigmentation defect
neurofibromatosis
neurocristopathy with peripheral nerve tumors
DiGeorge syndrome
neurocrisopathy affecting the development of the craniofacial and cardiovascular system
components of CNS
brain and spinal cord
components of PNS
nerves (sensory and motor)
sensory (afferent) neurons
signals from receptors to the CNS
motor (efferent) neurons
signals from the CNS to affector tissues
interneurons
signals between neurons
neuroglial cell funciton
provide neuronal support and nutrition, maintain homeostasis, form myelin, participates in transmission
neuron characteristics
conducting potential, longevity, amitotic, high metabolic rate
nissl body
neuronal RER in the soma, aka “gray matter”
dendrite function
receive impulses and carry them to soma, increase surface area
axon function
carry AP away from soma, originate at axon hillock
3 parts of synapse
presynaptic neuron (send neurotransmitters), synaptic cleft, postsynaptic neuron (receptors on surface)
neuronal resting potential
-70mV
t/f. the cell is more negative on the outside of the cell
FALSE. more negative on the inside
what do leaky Na+ channels do?
aka graded potentials, allow of a little of Na to leak in and cause the dendrite to be depolarized. if the initial GP is sufficient, it can spread to the axon hillock and allow voltage gated ion channel to open for an AP
types of glial cells
astrocytes, oligodendrocytes, microglia, ependymal cells, schwann cells, satellite cells
astrocytes
CNS
largest and most numerous, maintains BLOOD BRAIN BARRIER, controls ionic environment, assists in migration of developing neurons
oligodendrocytes
CNS
produce and maintain insulating MYELIN sheaths that surround the neurons
microglia
CNS
specialized IMMUNE CELLS derived from wbcs that act as macrophages, clears unwanted cellular debris caused by cns lesions
ependymal cells
CNS
form lining of fluid filled ventricles of CNS, cuboidal/columnar cells and are a source of cerebrospinal fluid, circulates CSF with cilia
satellite cells
PNS
surround neuronal cells in ganglia, provide structural and metabolic SUPPORT for neurons (insulation and efficient metabolic exchange)
schwann cells
PNS
myelinate a SINGLE portion of a SINGLE axon
t/f. an axon with a small diameter conducts an AP faster than one with a large diameter.
false. axons with larger diameters have less resistance and can conduct an AP faster
CT organization of the PNS
endoneurium surrounds each axon, perineurium surrounds bundles of neurons (fascicles), epineurium surrounds all the fascicles
dura mater
dense CT continuous with perosteum, simple squamous epithelium along internal surface
arachnoid
trabeculae attach to pia mater and create subarachnoid space with HA cushioning, Ct with no blood
pia mater
loose/dense CT with many blood vessels, neuroglial processes separate pia mater from neural components
central gray matter
unmyelinated, nerve cell bodies
peripheral white matter
myelinated axons and associated neuroglial cells
type of cell in cerebral cortex
purkinje cells
cells in cerebral medulla
white matter and glial cells
number of pairs of spinal nerves
31
divisions of PNS
somatic and autonomic
