Electrochemical Basis of Nerve Function Lecture 4

Question 1

types of electrical potentials in neurons

Answer 1

resting membrane potential

generator potentials

action potentials

Question 2

resting membrane potential

Answer 2

difference in electrical potential across membrane when neuron is at rest

-70

Question 3

receptor potential

Answer 3

at receptor site

sensory nerve end receptor

modality gated channel

excitatory

Question 4

synaptic potential

Answer 4

at synaptic site on postsynaptic membrane

ligand gated channel

excitatory or inhibitory

Question 5

action potentials

Answer 5

stimulated when threshold is reached

starts at axon hillock - conducts down axons

voltage gated channel

multipolar

Question 6

two forces of ion migration

Answer 6

chemical and electrical gradients

Question 7

what controls the ability of ions to move across membrane?

Answer 7

opening and closing of channels

Question 8

voltage gated

Answer 8

open in response to changes in electrical potential across cell membrane

Question 9

ligand gated

Answer 9

open in response to neurotransmitter attaching to its receptor

Question 10

modality gated

Answer 10

open in response to 
mechanical forces 
temperature 
chemical exposure 
light

Question 11

g-protein coupled

Answer 11

opens in response to intracellular 2nd messenger

Question 12

the net flow of ions is proportional to

Answer 12

ability to flow X driving force

Question 13

the driving force of ionic currents

Answer 13

difference between the membrane voltage & the equilibrium potential for that ion

Question 14

subtypes of membrane channels (serotonin)

Answer 14

same neurotransmitter activate both membrane channels but have different action depending on receptor cell type

Question 15

temporal summation

Answer 15

when the same presynaptic fiber fires action potential in quick succession

the individual EPSP add together

Question 16

Ach neurotransmitter + nicotinic receptor =

Answer 16

excitatory response

Question 17

End Plate Potential

Answer 17

a type of excitatory post-synaptic potential (EPSP)

Question 18

conductance of post synaptic membrane increases in proportion to __

Answer 18

of channels opened and conductance of an individual Ach receptor

Question 19

inhibitory synapse (IPSP)

Answer 19

inhibit neuron activity

Question 20

Glycine and GABA

Answer 20

neurotransmitter open to anion

Open Cl channels –> into cell –> makes cell negative = hyperpolarization –> outward current

Question 21

spatial summation

Answer 21

when two or more presynaptic inputs are active at the same time – their individual EPSP add together

Question 22

G protein coupled neuromodulation

Answer 22

when neurotransmitter binds to receptor & the channel does not open up immediately

Question 23

G protein neuromodulation causes

Answer 23

phosphorylation of proteins —> this causes channels to open up

Question 24

changes in ionic equilibrium following spinal cord injury

Answer 24

(similar to Na/K transporter)

spinal injuries can cause long term dysregulation of KCC2 transporter - that depolarizes the cell

Question 25

upstroke

Answer 25

inward current depolarizes

Na goes in

-70 to 40

Question 26

repolarization

Answer 26

depolarization inactivates gates of Na+ channels (closes more slowly than it opens)

K+ channels open

Question 27

hyperpolarization

Answer 27

K+ conductance is high

-90 mV

Question 28

absolute refractory period

Answer 28

Na channels have just inactivated and cannot be reopened

another stimulus can’t generation action potential

Question 29

relative refractory period

Answer 29

begins as the inactive channels are returning to their resting closed state

Na in resting = K open

another action potential can generate

Question 30

speed conduction of action potential is related to _

Answer 30

presence or absence of myelin, temperature, & fiber diameter

NOT related to stimulus strength