L13 Neurons and Glia Flashcards
what is the MAIN difference between neurons and glia?
the mean they transfer information
how are neurons and glia similar?
- resting membrane potential fluctuations
- gap junctions
- receptors
- voltage gated ion channels
- transporters
- pumps
- calcium signaling
- transmitters
what are the differences between neurons and glia?
neurons - generate action potentials and excitatory/inhibitory posysynaptic graded postentials
Glia - intra- and inter-cellular calcium signaling
what are the structural classifications of neurons?
neuron structure and function are related
there are different types of neuronal structure - i.e. striatal spiny neurons
*they don’t all look exactly alike, but most of them share common characteristics - soma, dendrite, axon etc.
what is neuron morphology related to?
signal receptor and transmission!
what is an example of multipolar neuron?
many dendrites, 1 axon
CNS - brain and spinal cord = motor n. in spinal cord anterior horn
what are examples of bipolar neuron?
sensory neurons
retinal bipolar cells
what are examples of pseudo-unipolar neurons?
sensory neurons in DRG
baroreceptor-sensitive cells in nodose ganglion?
what is a Nissl body?
histological sign of rough ER, site of protein synthesis
what makes up neurites?
the axon and the dendrite
what connects the soma to the axon?
axon hillock/initial segment
what is a synaptic bouton?
contains NTs waiting to undergo exocytosis
what do neurons form?
networks
what is an efferent neuron?
info from CNS to PNS = motor neuron
what is an afferent neuron?
info from PNS to CNS = sensory neuron
what are interneurons?
info with the CNS or within the PNS
the size the neuron diameter is directly related to what?
the speed of conduction
*note - myelin is considered in diameter size
myelin speed up rate of conduction!
the larger the diameter, the faster the conduction
what is the role of the cytoskeleton?
traffics material between soma and neurites
and support/maintain neuronal shape
what makes up the cytoskeleton?
- microtubules
- neurofilaments (intermediate filaments)
- microfilaments
what are the 3 filaments of the cytoskeleton joined to?
- eachother
- ER
- vesicles
BY PROTEIN bridges
how does the cytoskeleton traffic materials?
anterograde axonal transport - soma to nerve ending
retrograde transport - nerve ending to soma
what drives anterograde transport?
kinesin
what drives retrograde transport?
dynein
what material are transported in fast and slow anterograde transport?
fast- vesicles, mitochondria
slow - cytoskeleton molecules, soluble proteins and enzymes
what materials are transported in retrograde transport?
lysosomes
enzymes
recycled vesicular membrane
what viruses use retrograde transport along microtubules to inject neurons?
- herpes virus
- polio virus
- rabies virus
- parvovirus
what are types of glia in CNS?
astrocytes microglia oligodendrocytes ependymal cells tanycytes choroidal epithelial cells perivascular astrocytes perivascular microglia
what are types of glia in PNS?
Schwann cells
peripheral astrocytes/enteric glia
satellite glial cells
what is the function of CNS Astrocytes?
- maintain cerebral blood flow and ionic osmotic balances
- store glycogen and supply neurons with lactate for energy
- reg. K+ in microenvironment of neurons
- release and take up NT
- send info as intra- and intercellular calcium waves
- release GF
- major site of cholesterol synthesis in brain!
what supports the formation of neuronal synapses (synaptic plasticity)?
cholesterol - secreted as APO-E containing HDL like particles
how does CNS astroglial cells regulate K+ concentration?
rise in K+ prevented by removal of K+ via pump and transporter protein
what are the macrophages of the CNS?
microglia
what have lately played a role in reg. inflammatory system for astrocytes?
microglia
what are microglia?
immunocompetent and phagocytic cells in the CNS ,which in the event of injury, inflammation and disease, become activated, reactive
what myelinates CNS axons?
oligodendrocytes
can wrap MANY axons per cell
what generates oligodendrocytes?
progenitor cells
why does saltatory conduction occur?
because of the nodes of Ranvier
where do ependymal cells form?
the walls of brain ventricles
what is the function of choroid plexus epithelial cells?
secrete CSF
transfer molecules from blood into CSF
what are perivascular astrocytes?
associated with the neurovascular unit
responsible for maintaining cerebral blood flow and ionic and osmotic balances in brain
what are tanycytes?
4 seperate populations of bipolar cells possibly link CSF to neuroendocrine events also indicated as a class of neural stem/progenitor cells
what are characteristics of Schwann cells?
- provide myelination
- phagocytic activity
- support PNS nerve regen.
Can wrap 1 axon with cell
what are enteric glia?
- in intrinsic ganglia of the digestive system
- associated with neurons in the enteric NS
- morpholigic and molecular similarities to CNS astrocytes
what are satellite glial cells?
-surround neurons in sensory, sympathetic, and parasympathetic ganglia
can axons in the PNS regenerate?
yes - schwann cells can re-myelinate the axon
can axons in the CNS regenerate?
impossible..?
what is Wallerian degeneration?
following injury distal to site of axonal damage
what is chromatolysis?
axon is sectioned close to the cell body causing swelling and movement of cell organelles away from cell body
what is anterograde degeneration
causes degeneration of the neuron postsynaptic to the damaged neuron
what is retrograde degeneration
happens in neurons, sends inputs to the damaged neuron
what happens in amyotrophic lateral sclerosis (ALS)?
loss on neurons
what is glosis?
glial scar formation
what are demyelination diseases?
HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP)
MS
Guillain-Barre syndrome
Charcot Marie Tooth disorder
what are tumors of glial origin?
schwannoma
glioblastoma
where are reactive astrocytes and activated microglia found?
found around degenerating neurons in various inflammatory or degenerative disorder in the CNS
may play neurotixic or neuroprotective roles
neuron are what type of cell?
excitable
