SLE1/MODULE 2- Activation Signals Flashcards
neuron is a type of ____
cell
where do neurons sit
extracellular fluid (ECF)
concentration gradient
refers to the movement of ions, into/out of the neuron
membrane potential
the change in potential across a cell membrane
resting membrane potential
no active signaling is occuring
-cell is at resting state
how do cells communicate
through membrane potential changes + movement of ions
resistance
how hard it is for an ion to cross the membrane
if there are a lot of doors/channels for the ion to go through, there is low/high resistance
LOW resistance
-high resistance if there are few channels
movement of ions causes ____
depolarizaition/hyperpolarization
depolarization
becoming more positive
hyperpolarization
becoming more negative
what does cell depolarization/hyperpolarizaiton do
modulates the chances of neuronal discharge
the neuron rests at a positive/negative membrane potential
negative
how is resting membrane potential (RMP) disrupted
ionic flow
ionic flow
the diffusion of ions
ions typically flow in what direction
high to low concentration
-different if energy is inputted into the system
through what does diffusion occur
via resting channels that are constantly open
if a bunch of positive ions enter a cell, we have depolarized/hyperpolarized
depolarized
if a bunch of positive ions exit a cell, we have depolarized/hyperpolarized
hyperpolarized
if negative ions enter a cell, we have depolarized/hyperpolarized
hyperpolarized
if negative ions exit a cell, we have depolarized/hyperpolarized
depolarized
Na+ goes into/out of cell
into (influx)
K+ goes into/out of a cell
out of (efflux)
why do nerve + muscle cell membranes generate potential differences
to pass current or to store charged particles
what does the membrane consist of
-lipids
-proteins
what is the membrane also called
phospholipid bilayer
phospholipid bilayer is permeable/impermeable
almost impermeable
-very tightly bound + almost impermeable to ions
-ions that CAN cross the membrane do so through specialized proteins, called ion channels
another name for ion channels
conductors
conductors enable nerve + muscle cells to do what
transmit changes in membrane potential
lots of ion channels/conductors = low/high resistance = low/high conductance
low resistance + high conductance
if ions pass through ion channels in a certain direction, what will happen
memrbane potential will change
3 properties of ion channels
-conduct ions rapidly
-recognize + select specific ions
-most of them open + close (gating) in response to specific electrical, mechanical, or chemical stimuli
are channels specific to specific ions
YES
-only recognize specific ions
-won’t let just any ion through
4 primary types of ion channels
-ligand-gated
-phosphorylation-gated
-voltage-gated
-stretch or pressre-gated
ligand-gated ion channel
binding of a chemical transmitter
-chemical transmitter binds to ion channel to open/close
phosphorylation-gated ion channel
phosphorylation of protein
-protein gets a phosphate added on
voltage-gated ion channel
change in membrane potential
-open/close in response to changes in membrane potential
-MOST IMPORTANT
stretch or pressure-gated ion channels
mechanical stimulus
-mechanical stimulus occurs + the channel is responsive to that particular stimuli
ligand-gated channels
open when a chemical ligand binds to a receptor site to allow ion flow
voltage-gated channels
open when a voltage changes to allow ion flow
2 types of voltage-gated channels
-Na+ channels
-K+ channels
Na+ channels are slow/fast to open
fast
K+ channels are slow/fast to open
slow
leak channels
channels without gates
-ions can move however they like, freely
-cell can be at resting membrane potential with these channels because as things go in, the same amount go out at rest
leak channels are ____ at rest
active
leak channels are largely responsible for establishing what
resting membrane potential
leak channels have selective permeability to ____
K+
-but also some Na+ and Cl-
are leak channels enough to re-establish concentrations of ions after muscle activation on their own
no
-if an AP happened, concentrations deviate from normal + leak channels ARE NOT enough to re-establish the original concentrations prior to the AP
equation for calculating resting membrane potential
Goldman Hodgkin Katz equation (GHJ)
Goldman Hodgkin Katz equation considers what 3 primary ions
-sodium
-potassium
-chloride
THESE IONS ALL IMPACT RMP
why do we frequently see squid nerve in physiology
because it’s nervous system is very simplistic
what unit is cell membrane potential measured in
mV
concentration is indicated by what
[brackets]
what unit is concentration measured in
millimoles