Membranes

Question 1

what is an electric current

Answer 1

rate of flow of electric charge past a point or region

Question 2

when does an electric current exist

Answer 2

when there is a net flow of electric charge

Question 3

what is a voltage

Answer 3

electric potential difference between two points (inside vs outside of neuron)

Question 4

what are the two opposing forces that voltage depends on

Answer 4

electrostatic force and molecular diffusion force

Question 5

what is electrostatic force

Answer 5

attraction of opposite charges that increases as distance decreases (coulombs law)

Question 6

what is molecular diffusion force

Answer 6

eventual equal distribution of molecules due to random motion (from high to low concen)

Question 7

what are the states of a voltage gated channels

Answer 7

open, closed, inactivated

Question 8

when can a voltage gated ion channel be inactivated

Answer 8

in the presence of Na+ (helps repolarise the cell - inside more negative)

Question 9

what are gates of voltage gated ion channels

Answer 9

event that causes the ion channels to change in the first place (ex: gated by a change in voltage)

Question 10

how do ligand gated ion channels open

Answer 10

when they come in contact wtih a ligand (ion or other compound) - similar to lock and key

once molecule binds, channel opens, ions flow

Question 11

where are thermal/mechanical gated ion channels

Answer 11

sensory neurons
mech gated also in GTOs and muscle spindles

Question 12

why do metabotropic ion channels open

Answer 12

result of enzyme cascade in the neuron triggered by binding of small number of NTs (ligands)

ligand DOES NOT open the channel - only opens after binding of enzyme complexes inside the cell

Question 13

advantage of metabotropic ion channels

Answer 13

signal amplification - 1 NT can trigger 100s of primary enzymes which trigger 1000s of secondary enzymes