Membrane Potential, Action Potential And Synaptic Transmission

Question 1

what is membrane Potential?

Answer 1

potential difference between the inside of a cell and the outside of the cell.

Question 2

what are excitable cells?

Answer 2

cells that are able to fire action potentials

Question 3

what are cardiac and skeletal muscle resting potentials?

Answer 3

-80 to -90 mV

these cells have the largest resting potentials

Question 4

what are the nerve cells resting potentials?

Answer 4

-50 to -75 mV

Question 5

what molecules are able to pass freely through the the lipid bilayer?

Answer 5

hydrophobic and small molecules , gasses

Question 6

what is the equilibrium potential?

Answer 6

membrane Potential where the net flow through any open channel is zero.

Question 7

what is the equilibrium constant for potassium?

Nerst equation

Answer 7

V= ((RT)/zF) in ([K+]o)/[K+]i)

Question 8

what is the full/final Nerst equation?

Answer 8

Ek = (61/z) log10 ([K+]o/[K+]i)

Question 9

what is chemical gradient?

Answer 9

difference in solute concentration across a membrane

Question 10

what is electrical gradient?

Answer 10

differences in charge across a membrane.

Question 11

what are the effects of increasing membrane permeability of a molecule?

Answer 11

moves the membrane Potential towards equilibrium for that ion.

Question 12

what are measures of controlling channel activity?

Answer 12

ligand gating
voltage gating
mechanical gating

Question 13

what is EPSP

Answer 13

excitatory post synaptic potential - post synaptic potential that makes a post synaptic neuron more likely to fire an action potential.

Question 14

what is Ipsp?

Answer 14

inhibitory post synaptic potential- opening of ligand gated channels (e.g. K+ ion channels) that cause hyperpolarisation. - inhibit firing of action potential.

Question 15

what is an action potential?

Answer 15

the change in electrical potential associates with the passage of an impulse along the membrane of a muscle or nerve cell.

Question 16

True or False

action potentials last longer in skeletal muscle than cardiac muscles

Answer 16

False (lasts longer in cardiac muscles expecially ventricular myocytes).

Question 17

True or False

depolarisation leading to to action potential occurs at -40mV

Answer 17

True

Question 18

what us a voltage clamp?

Answer 18

allows toy to change the membrane Potential then measure the current time that produces that membrane Potential.

Question 19

True or False

to generate an actio n potential, a large change in ion concentration is required.

Answer 19

False!

Question 20

is sodium potassium pump involved in repolarisation of the action potential?

Answer 20

NO!

Question 21

what is relative refractory period?

Answer 21

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.

Question 22

what is absolute refractory period?

Answer 22

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.

Question 23

basic structure of the voltage gates Na+ channel

Answer 23

one subunit consisting of four similar repeats (only one alpha subunit)

Question 24

basic structure of the K+ voltage gated channels

Answer 24

consists of 4 individual alpha subunits (a1-a4).

Question 25

what is saltatory conduction?

Answer 25

initiation if action potentials at the nodes of ranvier only, not in mylinated sections.

Question 26

what enzyme breaks down acetylcholine?

Answer 26

acetylcholine esterase Duh!

Question 27

what is the reversal (or Nerst) potential?

Answer 27

membrane Potential at which there is no net flow of a particular ion from one side of the membrane to the other.