Topic 2 Flashcards
(46 cards)
Electrical signalling
Action potenital
Chemical signalling
Occurs at the synapse with neurotransmitters
Axon hillock
Where AP are generated from, must be of a certain magnitude/ reach electrical threshold for it to occur
Resting membrane potential
-65 mv
Depolarisation
influx of Na+
Hyperpolaristaion
efflux of K+
electrical differnce
resting membrane potential - the electrical difference outside the cell compared to the inside
Factors to generate the resting membrane potential
1) Concentration of ions in the cytoplasm and in the ECF
2) permeability of membrane
3) Transporters present
Neurotransmitter in lipid bilayer
they can not cross, hence why they need a transporter
ion channels
Made of protein
will open and close to allow passage of ions
uncharged solutes
pass through passively
charged solutes
require energy as they are going against the concentration gradient
this creates an eletrical gradient
Gradient
is magnitude and direction of flow
determine by electro-chemical gradient
Membrane is most permeable to
K+ ions, usually as more potassium channels are present
also taking in more k+ reduces likelihood of firing an AP
Selectivity of channels
dependant on:
pore size
what amino acid lines the channel
Transportes
are embedded in the membrane
have 2 separate gates at both ends of the membrane
coupled transport
when a transporter moves 2 molecules at a time, the first one provides the second one with ATP to move
Symporters
type of transporter
moves soltes in the same direction
Antiporters
type of transporter
moves solutes in opposite directions
ATPase
3 Na+ OUT
2 K+ IN
Leaky k+ channels
always open k+ channels
passive
allows k+ to leave the cell
makes resting mebrane potential more negative
Na+ leak
At rest there is an inward leak of sodium, this pushes the extra k+ out thats being brought in by ATPase
volatge gated k+ channels states
open an closed
volatage gated Na+ channel states
activation, inactivation , resting state
