Signalling in the Nervous System

Question 1

What are the names of the ‘gaps’ between myelin on axons of neurons?

Answer 1

Nodes of Ranvier

Question 2

What are the names of the processes which stem from the cell body of neurons and receive input from receptors/other neurons?

Answer 2

Dendrites

Question 3

Describe the Nernst equation for calculating equilibrium potential.

Answer 3

E = (RT/zF)ln ([ion outside cell] / [ion outside cell])

R = gas constant
z = valence
T = temperature (K)
F = faraday constant

Question 4

What is the typical resting membrane potential of a neuron?

Answer 4

Between -60mV to -70mV

Question 5

What is equilibrium potential?

Answer 5

The membrane potential where there is no net movement of ions in or out of the cell

Question 6

What is an action potential?

Answer 6

A very brief but dramatic change in membrane potential

Question 7

Action potentials are an all or nothing response. T/F?

Answer 7

True

Question 8

Depolarisation is due to the fast opening of voltage gated channels for which ion?

Answer 8

Sodium

Question 9

Repolarisation is due to the slow opening of voltage gated channels for which ion?

Answer 9

Potassium

Question 10

Lidocaine is a local anaesthetic. What is its mechanism of action?

Answer 10

Blocks sodium channel to prevent depolarisation

Question 11

Lidocaine is a local anaesthetic which inhibits depolarisation by blocking sodium channels. What other class of drugs also works by blocking these channels?

Answer 11

Antiepileptic drugs

Question 12

What factors determined the destination of current in a neuron?

Answer 12

The axon diameter

The number of open pores or channels in the membrane

Question 13

Describe saltatory conduction in myelinated neurons

Answer 13

The action potential ‘jumps’ from node to node allowing faster transmission of the cell

Question 14

What are the symptoms of Gullain-Barre syndrome?

Answer 14

Progressive motor weakness

Motor and sensory loss (mainly in the face, limbs, trunk and diaphragm)

Question 15

Gullain-barre is an inflammatory disease which can be caused by a prior infection. T/F?

Answer 15

True

Question 16

Describe the process of synaptic transmission in neurons

Answer 16

The action potential enters the presynaptic terminal, allowing calcium enter through voltage gated calcium channels. calcium causes docking of synaptic vesicles containing neurotransmitters which are then released by exocytosis. The neurotransmitter then binds to and activates receptors on the postsynaptic membrane. This causes an influx of either sodium (excitatory) or calcium (inhibitory) in the post-synaptic cell which causes, respectively, action potential firing or hyper polarisation to prevent depolarisation

Question 17

Excitatory and inhibitory postsynaptic potentials are graded, threshold potentials which bring the resting membrane potential either closer to or further from threshold potential. T/F?

Answer 17

True

Question 18

Give example of biogenic amine neurotransmitters?

Answer 18

Catecholamines, 5-hydroxytrytamine, serotonin

Question 19

Glutamate is an amino acid neurotransmitter which is excitatory. Name an inhibitory amino acid neurotransmitter?

Answer 19

Gamma-aminobutyric acid (GABA)

Question 20

Botulism results in skeletal muscle weakness and paralysis of the diaphragm. How is this achieved?

Answer 20

When the botulinum toxin is ingested from clostridium bacteria in contaminated food, this disrupts exocytosis to prevent ACh release

Question 21

How do autoantibodies act in myasthenia gravis to cause severe muscle weakness?

Answer 21

These bind to and block ACh receptors in the postsynaptic membrane at the motor end plate

Question 22

Which tissues are most affected by myasthenia gravis?

Answer 22

Eyelids
Eyes
Face
Throat
Limb muscles

Question 23

What technique is used to investigate cognitive processes in response to a stimulus?

Answer 23

Electoencephalography (EEG)

Question 24

How is PET used to locate brain activity while performing a task?

Answer 24

It measures blood flow via a small dose of radioactive material injected into the bloodstream

Question 25

PET uses blood flow to locate brain activity while performing a task. What other imaging technique can be used similarly?

Answer 25

functional MRI

Question 26

How is transcranial magnetic stimulation used to investigate Brian activity?

Answer 26

This uses electormagnetic stimuli to cause depolarisation or interrupted firing to interrupt brain activity while performing a task