Ibhs 524 Exam 2 Lecture 5

Front 1

CNS glial cells and PNS glial cells

Back 1

CNS glial cells: astrocytes, microglia, ependymal cells, oligodendrocytes; PNS glial cells: schwann/satellite cells

Front 2

astrocytes

Back 2

structural framework/cytoskeleton, maintain extracellular environment (osmolarity, nutrients, GJ), neural dev in utero, bbb, stabilize damaged neural tissue

Front 3

microglia

Back 3

smallest, phagocytose debris, monocyte enter CNS during embryogenesis

Front 4

ependymal cells

Back 4

line brain vesicles and central canal of spinal, CSF

Front 5

oligodendrocytes

Back 5

make myelin for CNS, cencentric layer, wrap axons, ranvier (unmyelinated), internode (single myelinated region)

Front 6

white matter

Back 6

lipid = white color; regions of CNS/PNS, myelinated axons

Front 7

gray matter

Back 7

CNS/PNS with neuron cell bodies, dendrites, unmyelinated axons

Front 8

what give gray matter its color?

Back 8

clusters of rough ER & ribosomes = nissl bodies --> gray color

Front 9

PNS neuroglia

Back 9

not protected by bbb, blood-CSF barrier or cranium....protected by neuroglia

Front 10

satellite cells

Back 10

protect ganglia, regulate gases, nutrients, NT

Front 11

schwann cells

Back 11

produce myelin for PNS axons, cover only one axon, unmyelinated axons also covered (not myelinated/concentric), protect ECF

Front 12

what is the primary and secondary damage that occurs with demyelination disorders

Back 12

primary: myelin neuroglia; secondary: axons --> poor neurotransmission

Front 13

Guillan Barre Syndrome

Back 13

immune mediated loss of PNS myelin, bacterial/viral/vaccine, acute Ab, plasmapheresis

Front 14

MS

Back 14

immune mediated loss of CNS myelin, females, 1st degree relative

Front 15

etiology of MS, pathology, tx

Back 15

autoimmune disease, viral mimicry // chronic, cytokines recruit macrophage...tx: glucoc/InterferonB, relaxants

Front 16

why is the cell interior more negative?

Back 16

permeability, Na+/K+ pump, fixed negatively charged protein

Front 17

electrical gradient

Back 17

electrical gradients can either reinforce or oppose the chemical gradient for each ion

Front 18

equilibrium potential

Back 18

equal but opposite chemical and electrical gradients;at rest, the membrane permeability for K+ is high/Na+ low

Front 19

depolarization

Back 19

less polar, Na+ influx

Front 20

repolarization

Back 20

restores resting membrane potential, positive ions leave cell

Front 21

hyperpolarization

Back 21

membrane potential moves away from zero. K+ efflux, Cl- influx, decrease chance of generating an AP

Front 22

what channel has an activation and inactivation gate

Back 22

voltage gated channels

Front 23

AP

Back 23

transmits electrical signal thru long distances (self generating at nodes). AP will happen if threshold is reached

Front 24

threshold

Back 24

membrane potential (-60) at which many voltage gate Na+ channels open up to initiate an AP

Front 25

what causes AP

Back 25

graded potentials: enough graded potentials are generated such that threshold is reached.

Front 26

graded potential

Back 26

local change, @ dendrites/soma/axon hillock, opens gated channel, can be depolarizing or hyperpolarizing depending on channel open

Front 27

do many cells have GP? regenerating? larger than AP? magnitude of depolarization depends on what?

Back 27

yes (motor end plate/gland), non regenerating, no, stimulus of AP

Front 28

what is the self regenerating wave of electrochemical activity due to?

Back 28

opening of many voltage gated Na+ channels on the axon

Front 29

at threshold, what is the cell more permeable to?

Back 29

Na+

Front 30

depolarization

Back 30

ligand Na+ open on soma, Na+ in soma (local current), go to -60, AP not at hillock but GP can sum, VG Na+ open at initial segment (act gate), Na+ IN neuron (-60-->30), propagation

Front 31

repolarization

Back 31

@ +30 VG Na+ close, VG K+ open; -70, VG K+ shut --> -90 (hyperpolarized), Na+/K+ pump normalizes ion levels --> -70 (ATP needed)

Front 32

what is ARP and RFP?

Back 32

absolute refractory period: neuron can't generate another AP; relative refractory period: neuron can generate another AP (stronger stimulus needed for threshold)

Front 33

propagation of an AP

Back 33

AP at one site causes depo downstream at adjacent sites by bringing them to threshold

Front 34

why does the AP only propagate 'downstream'

Back 34

final outcome: depolarization of axon terminal --> NT release via opening of VG Ca2+ channels; electrical --> chemical

Front 35

continuous propagation

Back 35

unmyelinated axon, AP regenerated repeatedly along axon; open/close of VG Na+ takes time (increased E used)

Front 36

saltatory propagation

Back 36

myelinated axon; myelin increases membrane capacitance (decrease leakage of ions), AP only needs to be regenerated at nodes, high conc'n of VG Na+ at nodes (increased speed of propagation)