Cells of the Nervous System & Neurotransmitters at Synapses

Question 1

Neurons consists of

Answer 1

dendrites, cell body and axons.

Question 2

Axons are surrounded by a myelin sheath

which

Answer 2

insulates the axon and increases the speed of impulse conduction.

Question 3

Certain diseases destroy the myelin sheath and this can cause a

Answer 3

loss of co-ordination.

Question 4

Glial cells produce the myelin sheath and

Answer 4

support neurons.

Question 5

Neurons connect with other neurons (or

muscle fibres) at a

Answer 5

synaptic cleft.

Question 6

Impulses are relayed across the synaptic cleft by

Answer 6

neurotransmitters

Question 7

Neurotransmitters are stored in vesicles in

Answer 7

the axon endings of the presynaptic neuron.

Question 8

Neurotransmitters are released into

Answer 8

the synaptic cleft (on arrival of an impulse).

Question 9

Neurotransmitters diffuse across the cleft and

bind to

Answer 9

receptors (on the membrane of the

postsynaptic neuron)

Question 10

To prevent continuous stimulation of postsynaptic neurons,

Answer 10

neurotransmitters should be removed by enzymes or reuptake

Question 11

Receptors determine whether the signal is

excitatory or

Answer 11

inhibitory.

Question 12

Synapses can filter out weak stimuli arising

from

Answer 12

insufficient secretion of neurotransmitters.

Question 13

Summation of a series of weak stimuli can

release enough neurotransmitter to

Answer 13

trigger an impulse.

Question 14

Convergent neural pathways can release

enough neurotransmitter molecules to

Answer 14

reach threshold and trigger an impulse.