Excitable cell

Question 1

Forces that control ion movement

Answer 1

diffusion and electrical field

Question 2

How much current depends on

Answer 2

electrical potential (V)
Electrical conductance - how easy it is for charge to more from on point to another 

there is no flow if either of these = 0

Question 3

conductance measured in ?

Answer 3

siemens

Question 4

nernst equation vs goldmans

Answer 4

N = just 1 ion taken into account. calculates equilibrium potential
G = looks at relative permeabilities of more than 1 ion

Question 5

Action of calcium

Answer 5

pumps transpot calcium out of neuroness maintaining low intracellular. changes detected by many proteins used as a signalling ion
high intracellular concentration is toxic

Question 6

Eion?

Answer 6

equilibrium potential

if membrane where selectively permeable to that ion calculated using nernst equation

Question 7

Graded vs action potential

Answer 7

graded - variable size, pass both ways along neurone membrane. vary according to strength to stimulus
action - all or nothing, fixed size, propagate in 1 direction

Question 8

resting potential ?

Answer 8

set up by pumps that maintain distribution of charge molecules. sodium potassium atpase transport 2k into cell and 3na out

set up negative membrane potential

Question 9

Sodium channels

Answer 9

open in response to a depolarisation
need to repolarise so can remove the innactivation ball so can go again= refractory period
K channels lead to repolarisation
Na channels behind are closed s lead to unidirectional

Question 10

Factors affecting velocity ?

Answer 10

diameter - greater diameter the greater V

Myelin - insulate to stop leaking by saltatory conduction

Question 11

EPSP +IPSP

Answer 11

excitatory post synaptic potential and inhibitor.

eps can be shunted by the activation of a nipsp

Question 12

temporal vs spatial summation

Answer 12

spatial - multiple presynaptic

temporal - 1 over time