neurophys mst 1 Flashcards
glial cells in CNS
oligodendrocyte
microglia
astrocyte
ependymal cells
radial glia
bipolar neuron
has 2 ends
classification of neurons depends on what 4 factors
morphology
function
location
chemical
flow of information in neurones
dendrite -> cell body -> axon
where does integration occur in a neuron
cell body
FASTER COMMUNICATION?
axo-dendritic / axo-somatic
axo-somatic
glial cells in PNS
schwann cells & satellite cells
satellite cells
support cell bodies in PNS
schwann cells
myelination in PNS
astrocytes
blood-brain barrier
reuptake of NT
support CNS
bridging between neurons
microglia
clear up damaged cells
ependymal cells
create barriers between compartments
source of neural stem cells
increase complexity NS does what to
neuron : astrocyte
increase in astrocyte : neuron ratio
oligodendrocytes
arms of myelin to many axons
gap junctions on astrocytes
connection between astrocytes
(potassium gos through during spatial buffering)
blood flow during neuronal activity
increased blood flow to areas of neural activity
via. arterial dilation
molecules that can cross blood brain barrier
small lipid molecules
glucose
why do astrocytes release gliotransmitters?
regulates synaptic transmission between neurons and ecf in brain
via. d-serine & glutamate excitation
threshold
potential where passive responses become active ones
current
movement of charge
current depends on
- potential difference (V=IR)
- ability to move within substance - conductance G & resistance (G=1/R)
capacitance
ions interacting across membrane
gating
opening of channel
why is there different forms of channels
stimulated by different things
open/close at different rates
allow different amounts of ion to pass
voltage gated channels
open and close along an axon vis change in transmembrane voltage
ligand gated channels
ion acts as a ligand, binds to receptor
mechanically gated channels
sense touch = open
how are ion channels selective?
e.g. potassium within selectivity filter is in MOST RELAXED STATE, a different ion in this filter would not be as relaxed
major determinant for permeability to an ion
number of channels open
what CANT stimulate ion channel to open
increase ion conc outside compared to inside
equilibrium
point where conc & elec grads are balanced, no net ion movement
fast / slow
(ion channel & gpcr)
ION - fast
GPCR - slow
gpcr’s
metabotropic
amino acid NT’s
SMALL
glutamate, gaba, glycine
small NT’s
Ach, purines, AA’s, biogenic amines
biogenic amine NT’s
dopamine, adrenaline, noradrenaline, serotonin, histamine
peptide NT’s
what receptor
how many aa’s long?
via metabotropic receptors
3-30 AA’s long
diff between GABA & glutamate
gaba lacks carboxyl group
allowing for receptors to differentiate between
viatt
vesicular aa transporter
gaba & glycine have the same
transmembrane spanning domain
single AA chain that fits through membrane
which NT to Gs
NA
which NT to Gq
glutamate
which NT to Gi
dopamine
what NT’s use metabotropic
glutamate, gaba, histamine, A/NA, dopamine, serotonin, purines, Ach
dopamine synthesis (mainly)
substantia nigra & ventral tegmental area
electric potential
how much current will flow
conductance
ability of charge to move from a to b
what molecule causes rmp
potassium
b4 spectrin & AnKG
(& where is there high density of these?)
link na and k channels to membrane
alot at AIS & nodes
Nav isoforms
do different things, expression is diff for diff neurons -> this is plastic
myelin protein - MBP
compacts cytoplasm
myelin protein MOG &MAG
poke out of ecf, attract next layer
nodes
cluster of na channels
high capacitance`
via b4 & ankyrin
paranode
ends of nodes
via NFI55 - caspr - contactin
juxtaparanode
(& periaxonal space)
K+ channels
periaxonal space: between myelin and axon, transfers substrates between axon and myelin
saltatory conduction (myelin)
jump over myelin is not true because ap is intracellular
strength of ap decays at internode & is replenished at node
otto loewi & frogs
when heart in one chamber was stimulated, this stimulated heart in attached chamber -> chemical (NT)
neurotransmitter criteria
- produced w/in neuron
- stored w/in neuron
- depolarise neuron = release
- act on receptor after release
- degradation / reuptake
- frog heart (same affect when put on post syn)
classical NT
(strengths & duration)
fast and short
non-classical NT
slow and long
post synaptic density
dense b/c alot of protein receptors -> need alot of activation for ap
how does Ca2+ = vesicle fusion?
binds to release proteins
quantum
how many Ach?
amount of NT in one vesicle
det. min size of post syn potential
(10,000 Ach)
miniature end plate potential MEPP
change in membrane potential by single quanta
1/100th of end plate potential
co-transmitters
more than one NT released
low freq stimulation
clear core vesicles
high freq stimulation
large dens vesicles
vesicle protein - synapsin
tether vesicles together
vesicle protein - clathrin
coating
psd-95 protein (post density)
receptors
psd pallium
scaffolding (deep layer)
how many proteins do excitatory synapses have
1000
how many proteins do inhibitory synapses have
250
neuroligin/neurexin complex
adhesion between the two neurons (pre and post)
neuroligin
post synaptic
neurexin
pre synaptic
shanks
cytoskeletal proteins
bind homer to metabotropic glutamate receptors & IP3
gephrin
inhibitory synapses
hexagonal lattice interacts with inhibitory proteins
sensory transduction
convert interaction to change property of neuron to alter firing probability
what determines sensory info
type of neuron type NOT stimulus
rapidly adapting
transient firing
adapted -> no need to fire
slow adapting
fire throughout
glabrous skin
hairless skin
free nerve endings (glabrous skin)
pain cool heat receptors
pacinian corpuscle
vibration detectors
ruffini endings & merkel cell
slow adapting
meissner corpuscles
rapidly adapting
afferent fibres that lack specialisation detect what?
pain
muscle spindles
encode length
in parallel
golgi tendon organs
encode tension
in series
y (gamma) motor neurons
innervate intrafusal muscle fibres
tune static & dynamic responses to 1 prim aff
how does olfaction contribute to taste
diffusion of volatile odorants into the nasal cavity
granule cells
tuning of olfaction
round window
allows fluid to move
scala vestibuli (canal)
filled with perolinth
scala tympani
filled with endolinth
equilibrium potential vs membrane potential
eq: affected by electrochem grad of one cell
mem: affected by gradients of all ions
nernst equation
It relates the equilibrium potential of an ion to its intra- and extracellular concentrations.
calc eq potential
How many connexin subunits form one complete synaptic channel?
12
(6 subunits per connexon, 2*6)
connexon
subunit of gap junctions
black widow spider venom
promote massive exocytosis
active zone
where vesicles fuse on presynpatic
how does Ca2+ = NT release?
By binding to and inducing changes in synaptotagmin that cause the plasma membrane to curve
Which intracellular component facilitates the processes of endocytosis and exocytosis underlying synaptic communication?
cytoskeleton
(b/c proteins)
Which protein plays a key role in endocytosis?
clathrin
Which feature of an electrical synapse allows synchronizing the electrical activity of multiple neurons?
Bidirectional transmission of electrical signals
How would application of an intracellular Ca 2+ chelator affect the function of a synapse?
It would eliminate the postsynaptic potential and Ca 2+-dependent vesicle fusion.
gamma motor neurons
innervate intrafusual muscle fibres (improve accuracy of info)
