Glial Diversity

Question 1

what are the types of oligodendrocytes and what do they do?

Answer 1

myelinating oligodendrocytes: insluate and nourish, about 30 myelin sheets per oligodendrocyte
non-myelinating oligodendrocytes: nourish short axons

Question 2

what are some characteristics of oligodendrocytes?

Answer 2

make up 30% of all glia, continue oligodendrogenesis throughout life from oligodendrocyte precursor cells and myelin remodeling, lead to alterations in neuroplasticity by wiring together cells that fire together

Question 3

what do protoplasmic astrocytes do?

Answer 3

reside in gray matter and BBB, part of the tripartite synapse, provide structural support and clear glutamate/ions from synpase, synaptogenesis, pruning, fill space, each have a distinct domain they support and do not overlap with others

Question 4

what are some characteristics of astrocytes?

Answer 4

astrocytes are the most abundant type of glia in the CNS as seen by GFAP immunolabeling, there are two types: protoplasmic and fibrous astrocytes

Question 4

what do fibrous astrocytes do?

Answer 4

reside in white matter, end feet attach to capillaries in the BBB, provide structural support and nourishment to axons

Question 5

what are radial glia and what are the two types?

Answer 5

glia that guide cell migration in the cortex and elsewhere, bergmann and muller glia are the two subtypes

Question 6

what do bergmann glia do?

Answer 6

a type of radial glia in the cerebellum that promote granule cell migration, have microglia-like functions such as synaptic pruning and gliosis (scar tissue formation from glia in brain)

Question 7

what do muller glia do?

Answer 7

a type of radial glia in the retina that can dedifferentiate into neural progenitor cells, have microglia-like functions and conduct light

Question 8

what are ependymal cells and what are the 5 types?

Answer 8

ependymal cells are cells that line the ventricular system and the 5 types are: ependymocytes, tanycytes, marginal glia, perivascular glia, and velate glia

Question 9

what do ependymocytes do?

Answer 9

act as a barrier to the ventricular surface, their cilia help circulate CSF and their microvilli reabsorb CSF, chroroid plexus cells are a subtype of ependymocytes that make CSF from blood plasma

Question 10

what do tanycytes do?

Answer 10

line the border of the third ventricle and regulate blood -> CSF border and the CSF -> brain transport of molecules, permit bidirectional movement of fluids between the ventricles and the blood stream, adjacent to capillaries

Question 11

what do marginal glia do?

Answer 11

form a barrier between brain parenchyma and meninges, act as the first line of defense even though astrocytes get all the credit

Question 12

what do perivascular glia do?

Answer 12

part of the BBB, cover capillaries in the brain

Question 13

what do velate glia do?

Answer 13

chemical and structural barrier in glomeruli

Question 14

what kind of diseases can result from BBB failure?

Answer 14

alzheimers, parkinsons, and huntingtons disease

Question 15

what kind of diseases can result from protein accumulation?

Answer 15

alzheimers and alexanders disease

Question 16

what kind of diseases can result from abnormal pruning?

Answer 16

fragile X

Question 17

what kind of diseases can result from abnormal development?

Answer 17

rett syndrome, fragile X, and alexander disease

Question 18

what kind of diseases can result from CSF abnormality?

Answer 18

hydrocephaly

Question 19

what two diseases of those discussed are not heritable?

Answer 19

guillain barre syndrome: autoimmune response against myelin triggered by virus/bacteria, causes demyelination in the PNS
multiple sclerosis: autoimmune disease that attacks the myelin sheet stabilizing proteins which leads to demyelination that slows or stops action potentials and eventually leads to neuronal death

Question 20

quadripartite vs tripartite synapse

Answer 20

quadripartite: astrocytes, microglia, and pre/post synaptic cell
tripartite: astrocytes, pre/post synaptic cell

Question 21

what are some characteristics of microglia?

Answer 21

make up 15% of glia, have both baseline and activated states, triggered in alzheimers disease, stroke and ALS, neuroinflammation leads to neurodegeneration

Question 22

baseline vs activated state of microglia

Answer 22

baseline: support neurogenesis and synapses, phagocytosis, synaptic pruning/stripping
activated: activated when an invader is encountered, present antigens to lymphocytes, produce proinflammatory mediators, similar to macrophages

Question 23

what are the two types of schwann cells and what do they do?

Answer 23

myelinating: conductance, support regeneration by allowing the myelin sheath to remain so that a new neuron can fill the space
non-myelinating: covers small axons, supports, nourishes, phagocytosis of dead cells

Question 24

what are the two diseases caused by mutations on schwann cells?

Answer 24

charcot-marie-tooth: myelin protein gene mutation, demyelination/remyelination in PNS
guillain-barre: autoimmune response against myelin in triggered by virus/bacteria, demyelination in PNS

Question 25

how are satellite cells similar to other cells?

Answer 25

like schwann cells: they cover axons plus they cover sensory/autonomic ganglia
like astrocytes: support, nourish, and remove glutamate from synapses
like microglia: activated upon nerve injury, mount and inflammatory response and alter sensory neuronal activity

Question 26

oligodendrocytes to schwann cells are like microglia to which cell?

Answer 26

satellite cells

Question 27

oligodendrocytes selectively surround axons, whereas astrocytes selectively support cell bodies, true or false?

Answer 27

false, astrocytes also support axons

Question 28

what are the glia in the CNS vs the PNS?

Answer 28

CNS: oligodendrocytes, astrocytes, radial glia, ependymal cells, and microglia
PNS: schwann cells and satellite cells