Neuronal Communication

Question 1

CNS

Answer 1

brain and spinal cord

Question 2

PNS

Answer 2

all nerves and sense organs which feed into CNS

spinal fibres

Question 3

sensory neurones

Answer 3

carry ap from a sensory receptors to CNS

Question 4

motor neurones

Answer 4

carry an action potential from the CNS to the effectors

Question 5

nerve impulse

Answer 5

electrical signals produced by movement of ions across cell membranes

Question 6

sensory receptors

Answer 6

specialised cells that can detect changes in surroundings and create action potentials

Question 7

pacinian corpuscles

Answer 7

pressure sensor that detects changes in pressure on the skin

Question 8

potential gradient

Answer 8

cell negatively charged inside compared to outside and negative potential enhanced by negatively charged ions already inside the cell

Question 9

relay neurones

Answer 9

connect sensory and motor neurones

Question 10

why are neurones very long

Answer 10

transmit action potentials over a long distance

Question 11

dendrites

Answer 11

carry impulse towards cell body

Question 12

axon

Answer 12

carries impulse away from cell body

Question 13

advantages of myelination

Answer 13

transmit ap much faster
carry ap over long distances
more rapid response to a stimulus

Question 14

neurones at rest

Answer 14

when not transmitting an ap

Question 15

refractory period

Answer 15

time that allows the cell to recover after an ap and ensure they’re only transmitted in one direction

Question 16

saltatory conduction

Answer 16

process which the ap appears to jump from one node to the next to speed up transmission

Question 17

synaptic cleft

Answer 17

small gap between neurones as the ap cannot bridge the gap between 2 neurones

Question 18

role of a synapse

Answer 18

ap in pre-synaptic neurones release a neurotransmitter that diffused across the cleft to generate a new ap in the post-synaptic neurone and bridge the gap

Question 19

cholinergic synapse

Answer 19

synapses that use acetylcholine as the neurotransmitter

Question 20

if acetylcholine is left in the synaptic cleft…

Answer 20

it will continue to open sodium ion channels in the post-synaptic membrane and continue to cause ap

Question 21

role of acetylcholinerase

Answer 21

prevent acetylcholine causing an ap

Question 22

2 ways nerve junctions involve several neurones

Answer 22

several neurones from different places converging on one neurone
or
one neurone sending signals out to several neurones that diverge to different effectors

Question 23

temporal summation

Answer 23

several ap’s in the same pre-synaptic neurone

Question 24

spatial summation

Answer 24

ap’s arriving from several different pre-synaptic neurones

Question 25

excitatory post-synaptic potential (EPSP)

Answer 25

one ap passes down an axon to the synapse and causes vesicles to move and fuse with pre-synaptic membrane
the small number of acetylcholine diffusing produces a small depolarisation

Question 26

summation

Answer 26

may take several EPSPs to reach the threshold so they combine together to increase membrane depolarisation until it reaches

Question 27

inhibitory post-synaptic potentials (IPSPs)

Answer 27

produced by some pre-synaptic neurones reducing the effect of summation and prevent an ap in the post-synaptic neurone

Question 28

transducer

Answer 28

a cell that converts one form of energy into another (electrical impulse)

Question 29

myelinated neurones

Answer 29

has an individual layer of myelin around it

Question 30

action potential

Answer 30

a brief reversal of the potential across the membrane of a neurone causing a peak of -40mV

Question 31

resting potential

Answer 31

the potential difference across the membrane while the neurone is at rest -60mV

Question 32

neurotransmitter

Answer 32

a chemical used as a signalling molecule between two neurones at a synapse

Question 33

habituated

Answer 33

when the synapse is fatigued after repeated stimulation so the nervous system no longer responds to the stimulus

Question 34

local currents

Answer 34

movement of ions along a neurone close to the membrane caused by an influx of sodium ions

Question 35

nodes of Ranvier

Answer 35

gaps in the myelin sheath