Transduction and synapses

Question 1

what triggers action potentials?

Answer 1

depolarisation to threshold

Question 2

what triggers graded potentials?

Answer 2

stimulus, neurotransmitter

Question 3

does the size of action potentials change with the size of the stimulus?

Answer 3

no

Question 4

does the size of graded potentials change with the size of the stimulus?

Answer 4

yes

Question 5

where are action potentials located?

Answer 5

voltage gated channels

Question 6

where are graded potentials located?

Answer 6

receptors and post-synapse

Question 7

what is transduction at nerve endings?

Answer 7

conversion of stimulus energy to electrical energy through ion channels

Question 8

what is a pacinian corpuscle?

Answer 8

mechanoreceptor at nerve endings

Question 9

how does a pacinian corpuscle convert mechanical stimulus into electrical energy

Answer 9

stimulus distorts distorts the ion channels in the nerve ending causing depolarisation

Question 10

what is a synapse?

Answer 10

relay station between nerves (pre- and post- synaptic nerves)

Question 11

synapses are said to have plasticity, what does this mean?

Answer 11

means they can change for example if a nerve is damaged, then there can be “rewiring”

Question 12

name this nerve

Answer 12

pre-synaptic nerve

Question 13

name this structure

Answer 13

synaptic vesicles

Question 14

name this channel

Answer 14

chemically gated protein channel

Question 15

name this nerve

Answer 15

post-synaptic nerve

Question 16

name this space

Answer 16

synaptic cleft

Question 17

name this channel

Answer 17

Ca2+ channel

Question 18

what happens when an action potential arrives at a synapse from a pre-synaptic nerve

Answer 18

Depolarisation causes Ca2+ channels to open, Ca2+ enters pre-synaptic nerve ending
Vesicles fuse with membrane and release neurotransmitter into synaptic cleft
Neurotransmitter diffuses across synaptic cleft and binds to channels on post-synaptic nerve

Question 19

what is temporal summation?

Answer 19

an action potential arrives shortly after another one, their graded potentials are added together to generate an AP in post-synaptic nerve. If acting alone they wouldn’t reach threshold.

Question 20

what is spatial summation?

Answer 20

multiple pre-synaptic nerves synapse at one post-synaptic nerve, two graded potentials added together to generate an AP. If acting alone wouldn’t reach threshold.

Question 21

what is post-synaptic inhibition?

Answer 21

Inhibitory neurotransmitters cause inhibitory post-synaptic potentials through hyperpolarisation

Question 22

name an example of an inhibitory neurotransmitter and how it works

Answer 22

GABA - opens K+ and Cl- channels to hyperpolarise post-synaptic membrane

Question 23

what is pre-synaptic inhibition

Answer 23

Inhibitory nerve synapses with excitatory nerve before it synapses with post-synaptic nerve -> axo-axonal synapse

Results in decreased neurotransmitter released from excitatory presynaptic neurone