electrical signals Flashcards
characterized by temporary change in RMP, strength of it depends on size of stimulus
graded potential
stimularion of a neuron reaches a threshold that triggers active transport of ions known as an ___ ____
action potential
RMP: actively move ions against gradient; atp dependent
pumps
RMP: exchange ions
exchanger
RMP: ions to diffuse down concentration gradients when open
channels
two major classes of channels
leakage and gated
always open; more K+ than Na+ channels
(influx of Na+, efflux of K+)
leakage channels
open/closed based on environment
gated channels
types of gated channels
voltage, ligand, signal, mechanical
more K+ inside and Na+ outside, does what?
sets resting membrane potential
RMP results primarily from what three processes
- diffusion of ions down their conc. gradients (k+ leakage channels)
- selective permeability of plasma membrane (3 Na+ out, 2 K+ in)
- attraction of cations to anions
gated channel that requires a signal and occurs in cell bodies and dendrites
ligand gated
gated channel that requires change in RMP at the initial segment, axon hillock, axon
voltage gated
gated channel that is activated by mechanical change and is somatosensory
mechanically gated
the magnitude of graded potential can or cannot vary
can
this potential spreads passively and is short loved
graded
ligand gated channels can be ____ tropic or ___ tropic and are activated by extracellular ligand
iono or metabo
signal at same time but at different synaptic sites
spatial summation
signal at time back to back on same synapse
temporal summation
an action potential is started through what type of channel
voltage gated
what potential does not decay with distance and magnitude stays the same
action
ap is spread by
simple diffusion
action potential requires both ___ and ___ current flow
active and passive
all voltage gated channels open at _____
threshold
what ion in action potential has faster reaction time
Na+
at ___ mV Na closes and K opens
+35
if there was no myelin the axons would be poor conductors and signals would die out why?
current “leaks” out across axon membrane
what is the action potential location
axon hillock, axon
what is the graded potential location
dendrites, cell body
membrane change in graded potential is either what or what
depolarization (excitatory) or hyperpolarization (inhibitory)
unmyelinated axons; depolarization/repolarization step-wise and must move down entire membrane
continuous conduction
node, internode in myelinated fibers, AP passes down nodes, saves ATP (faster)
saltatory
anesthetics: prolongs inactivation of voltage-sensitive Na+ channel (cannot start another action potential): lidocaine
local
ketamine is similiar size to magnesium block in NMDA channel and blocks flow
intravenous anesthetics
