Neurotransmission W1

Question 1

voltage across membrane at rest?

Answer 1

-70mV

Question 2

which side of membrane is positive/negative?

Answer 2

+ extracellular
- intracellular

Question 3

3 ways to stimulate a resting neuron?

Answer 3

ligand gated ion channels
voltage gated ion channels
propagation of current

Question 4

effect of a stimulus on membrane potential

Answer 4

increase or decrease membrane potential

Question 5

threshold for membrane depolarization? what occurs when this is met?

Answer 5

-55mV
voltage gated Na channels open

Question 6

which channels open/close in depolarization/repolarization

Answer 6

depolarization - voltage gated Na channels open
repolarization - voltage gated K channels open, voltage gated Na channels close

Question 7

what triggers repolarisation

Answer 7

voltage reaches +40mV

Question 8

what occurs in the refractory period?

Answer 8

neuron is hyperpolarized and an action potential cannot be generated

Question 9

what does myelination facilitate

Answer 9

saltatory conduction

Question 10

how does saltatory conduction occur?

Answer 10

ions can’t pass across the fatty myelin layer, impulse jumps between nodes of Ranvier between myelin sheaths

Question 11

problems of unmyelinated axons

Answer 11

slow process
high energy requirement

Question 12

what conditions cause loss of myelin therefore impairing conduction?

Answer 12

Multiple Sclerosis (CNS)
Guillain Barre Syndrome (PNS)

Question 13

description of chemical transmission at a synapse?

Answer 13

action potential arrives, voltage gated Ca2+ channels open allowing Ca2+ to enter cell, this allows vesicle docking and neurotransmitter release. neurotransmitters bind to receptors, channels open/close. Vesicular membrane retrieved from plasma membrane, neurotransmitter removed by glial uptake (for enzyme degredation)

Question 14

inhibitory neurotransmitters?

Answer 14

GABA
serotonin
glycine

Question 15

excitatory neurotransmitters?

Answer 15

glutamate
adrenaline
noradrenaline

Question 16

inhibitory/excitatory synapse - what occurs in post synaptic cell

Answer 16

inhibitory - hyperpolarisation
excitatory - depolarisation

Question 17

example of neurotransmitter that can be both excitatory and inhibitory? what does this depend on?

Answer 17

dopamine
depends on type of post synaptic receptor it binds to

Question 18

2 types of summation?

Answer 18

spatial and temporal

Question 19

spatial summation description

Answer 19

simultaneous signals from multiple presynaptic neurons received by a single postsynaptic neuron

Question 20

temporal summation description

Answer 20

single presynaptic neuron rapid-firing signals to a postsynaptic neuron

Question 21

what does diazepam do in the nervous system

Answer 21

enhances GABA channel opening (inhibitory transmission)

Question 22

effects of overdose of diazepam

Answer 22

lethargy
slurred speech
poor co-ordination
bradycardia
hypotension
apnoea

Question 23

what is lethargy

Answer 23

pathological state of sleepiness or deep unresponsiveness and inactivity

Question 24

what does the resting state of a neuron require

Answer 24

energy!