Membrane Potential, Action Potential And Synaptic Transmission Flashcards
what is membrane Potential?
potential difference between the inside of a cell and the outside of the cell.
what are excitable cells?
cells that are able to fire action potentials
what are cardiac and skeletal muscle resting potentials?
-80 to -90 mV
these cells have the largest resting potentials
what are the nerve cells resting potentials?
-50 to -75 mV
what molecules are able to pass freely through the the lipid bilayer?
hydrophobic and small molecules , gasses
what is the equilibrium potential?
membrane Potential where the net flow through any open channel is zero.
what is the equilibrium constant for potassium?
Nerst equation
V= ((RT)/zF) in ([K+]o)/[K+]i)
what is the full/final Nerst equation?
Ek = (61/z) log10 ([K+]o/[K+]i)
what is chemical gradient?
difference in solute concentration across a membrane
what is electrical gradient?
differences in charge across a membrane.
what are the effects of increasing membrane permeability of a molecule?
moves the membrane Potential towards equilibrium for that ion.
what are measures of controlling channel activity?
ligand gating
voltage gating
mechanical gating
what is EPSP
excitatory post synaptic potential - post synaptic potential that makes a post synaptic neuron more likely to fire an action potential.
what is Ipsp?
inhibitory post synaptic potential- opening of ligand gated channels (e.g. K+ ion channels) that cause hyperpolarisation. - inhibit firing of action potential.
what is an action potential?
the change in electrical potential associates with the passage of an impulse along the membrane of a muscle or nerve cell.
True or False
action potentials last longer in skeletal muscle than cardiac muscles
False (lasts longer in cardiac muscles expecially ventricular myocytes).
True or False
depolarisation leading to to action potential occurs at -40mV
True
what us a voltage clamp?
allows toy to change the membrane Potential then measure the current time that produces that membrane Potential.
True or False
to generate an actio n potential, a large change in ion concentration is required.
False!
is sodium potassium pump involved in repolarisation of the action potential?
NO!
what is relative refractory period?
period of time after an action potential is fired whereby the ion (Na+) channels are recovering from inactivation- greater than normal stimulus is required to fire a second action potential.
what is absolute refractory period?
period of time after an action potential is fired whereby the ion (Na+) channels are inactivated- cannot fire a second action potential in this period.
basic structure of the voltage gates Na+ channel
one subunit consisting of four similar repeats (only one alpha subunit)
basic structure of the K+ voltage gated channels
consists of 4 individual alpha subunits (a1-a4).
what is saltatory conduction?
initiation if action potentials at the nodes of ranvier only, not in mylinated sections.
what enzyme breaks down acetylcholine?
acetylcholine esterase Duh!
what is the reversal (or Nerst) potential?
membrane Potential at which there is no net flow of a particular ion from one side of the membrane to the other.
