Resting Membrane Flashcards
(25 cards)
Resting K+ channel
always open
voltage-gated channel
opens and closes in response to changes in membrane potential
ligand-gated channel
opens and closes in response to neurotransmitters
signal-gated channel
opens and closes in response to intracellular signals
describe the neuronal membrane
- Phospholipid bilayer
- Effectively isolates the cytosol from the extracellular space
describe the cytosol and extracellular
fluid
Water:
* Lots of it both in and out of the cell
* Unevenly charged
* Easily dissolves polar molecules (ions)
Ions:
* Atoms and molecules with a net
electrical charge
* Cations: + charged ion
* Anions: - charged ion
describe ion channels
-membrane spanning
-requires 4 subunits to form a pore
-ion selectivity is determined by pore size and AA’s
diffusion
- Movement of ions from an area of
high concentration to an area of low
concentration
-happens due to concentration gradient
concentration gradient
- Difference in concentration
- Go until it reaches equilibrium
Common Ion Concentrations in Neuron
Na+: higher conc extracellular, drives in
K+: higher conc intracellular, drives out
Cl-: higher conc extracellular, drives in
Ca2+: higher conc intracellular, drives in
Current (I)
- Movement of electrical charge
- Measured in ampere (amps)
Voltage (V)
Electrical potential
* Difference in charge between the anode and cathode
Conductance (g)
- Ability of a charge to move
- Measured in siemens (S)
Resistance (R)
- Inability of a charge to move
- Measured in ohms (Ω)
- Inverse of conductance (g)
Ohm’s Law
Describes the relationship between Voltage, Current, and Resistance in any DC electrical circuit
Membrane Potential (Vm)
- Voltage across the
neuronal membrane - Resting membrane
potential - -65 to -70 mV
Equilibrium Potentials
difference in concentration of ions needed in order to reach equilibrium
what equation is used to calculate Equilibrium Potentials
nernst equation
Ion Pumps
enzymes that use energy (ATP) to transport ions
across the membrane
* Commonly against ion gradients
* Areas of low concentration to high concentration
Na K pump process
- Na+ in the cytoplasm binds to the Na K pump, high affinity for Na+
- phosphorylation, change in structure
- Na+ is then released into the ECF
- high affinity for K+, so K+ binds
- phosphorylation goes away, and K+ is released into the cytoplasm
- Shape goes back to normal
what sets the resting membrane
Primarily based on the
concentration gradient of
Na, K and to a small
extent Cl
passive leak channels of K+ leaving the cytoplasm
what calculates the resting membrane potential
goldman equation
if you want the resting membrane to become more positive
decrease K+ permeability, bc less K+ will leave the cell due to less permeability
if you want the resting membrane to become more negative
decrease Na+ driving force (less Na will enter cell)
increase K+ driving force (more K will leave the cell)
