lecture 27 - graded potentials - PoNF

give examples of graded potentials

generator potentials - sensory receptors

post-synaptic potentials - at synapses

end plate potentials - NMJ

pacemaker potentials - pacemaker tissues in heart

Function of graded potentials

decide when action potentials are fired in conjunction with axon hillock

small stimulus

small response

strong stimulus

large response

graded potential properties

decremental - become smaller as they travel

can be depolarising Orr hyper polarising - can excite or inhibit neurones

can summate - if 2 occur at same time, they can combine to make one big graded potential

Ionic basis of graded potentials

at rest lots of leaky K+ channels

opening of other ion channels generates other ion gradients

Hyperpolarising graded potential

make the cell more negative taking the membrane potential further away from zero

Depolarising graded potential

cell less negative but doesn't quite reach threshold