Introduction to neurones, nerve conduction and synaptic transmission

Question 1

What is the purpose of a dendrite?

Answer 1

To receive inputs from other neurones and convey graded electrical signals passively to the soma

Question 2

What is the purpose of the soma?

Answer 2

It is the synthetic and metabolic centre
Contains the nucleus, ribosomes, mitochondria and ER
It integrates incoming electrical signals that are conducted passively to the axon hillock

Question 3

What is the axon hillock?

Answer 3

Site of initiation of the “all or nothing” action potential

Question 4

What is the function of the axon?

Answer 4

Conducts output signals as action potentials to the presynaptic terminal
Mediates transport of materials between the soma and presynaptic terminal and vice versa by slow and fast axonal transport

Question 5

What is the function of the synapse?

Answer 5

Point of chemical communication between neurones

Question 6

What viruses will exploit retrograde transport to infect neurones?

Answer 6

Herpes
Polio
Rabies

Question 7

What are the different types of neurones?

Answer 7

Unipolar
Pseudounipolar
Bipolar
Multipolar

Question 8

Where can unipolar neurones be found?

Answer 8

Peripheral autonomic system

Question 9

Where can pseudounipolar neurones be found?

Answer 9

Dorsal root ganglion

Question 10

Where can bipolar neurones be found?

Answer 10

Retina

Question 11

Where can multipolar neurones be found?

Answer 11

Lower motor system

Question 12

What is the resting potential for a neurone?

Answer 12

-70 mV

Question 13

What is the threshold for a neurone?

Answer 13

-60 mV

Question 14

What channels allow for the upstroke and downstroke of the action potential in neurones?

Answer 14

Upstroke = Na+ 
Downstroke = K+

Question 15

Why do passive signals in neurones not spread far from their site of origin?

Answer 15

Current loss across the membrane accompanied by a reduced change in potential

Question 16

What are strategies utilised to increase passive current speed and therefore action potential velocity?

Answer 16

Decreased axial resistance of the axoplasm via increased axon diameter
Increased membrane resistance - addition of myelin provided by schwann cells in PNS and oligodendrocytes in CNS

Question 17

What is saltatory conduction?

Answer 17

Action potential jumping from one node of ranvier to the next

Question 18

What are examples of demyelinating disorders?

Answer 18

MS (CNS)

Guillan-Barre (PNS)

Question 19

What separates the pre and post synaptic membranes?

Answer 19

Synaptic cleft

Question 20

What holds the pre and post synaptic membranes together?

Answer 20

A matrix of fibrous extracellular protein within the cleft

Question 21

Where are the neurotransmitters stored in the neurone?

Answer 21

Vesicles within the presynaptic terminal

Question 22

What are the different types of synapses?

Answer 22

Axodendritic
Axosomatic
Axoaxonic

Question 23

What is the most common type of synapse?

Answer 23

Axodendritic

Question 24

What is the most common neurotransmitter of excitatory synapses in the CNS?

Answer 24

Glutamate

Question 25

What will glutamate activate?

Answer 25

Post synaptic, cation selective, inotropic glutamate receptors resulting in a depolarisation; excitatory postsynaptic potential

Question 26

What are the major amino acid neurotransmitters in the CNS?

Answer 26

Glutamate GABA Glycine

Question 27

What is the most common neurotransmitter of inhibitory synapses in the CNS?

Answer 27

GABA or glycine

Question 28

What will GABA/glycine activate?

Answer 28

Postsynaptic, anion selective, inotropic, GABA or glycine receptors generating a local, graded hyperpolarizaing post synaptic potential

Question 29

What is spatial summation?

Answer 29

Many inputs converge upon a neurone to determine its output

Question 30

What is a temporal summation?

Answer 30

A single input may modulate output by variation in action potential frequency of that in put

Question 31

What are the major amine neurotransmitters?

Answer 31

Dopamine Histamine Noradrenaline Serotonin

Question 32

What are the major peptic neurotransmitters?

Answer 32

``` Cholecystokinin Dynorphin Enkephalins Neuropeptide Y Somatostatin Substance P Thyrotropin releasing hormone Vasoactive intestinal polypeptide ```

Question 33

Which neurotransmitters are released from synaptic vesicles?

Answer 33

Acetylcholine Amino acids Amines

Question 34

Which neurotransmitters are released from secretory vesicles?

Answer 34

Peptides

Question 35

Which neurotransmitters mediate fast neurotransmission via inotropic ligand gated ion channels?

Answer 35

``` Glutamate GABA Glycine Acetylcholine Serotonin ```

Question 36

Which neurotransmitters mediate slow neurotransmission via metabotropic G-protein coupled receptors?

Answer 36

All except glycine

Question 37

What are the modes of neurotransmission?

Answer 37

Direct | Indirect

Question 38

How does direct neurotransmission work?

Answer 38

Ionotropic receptors The receptor is an integral component of the molecule that forms the channel is controls Gating of channel is rapid

Question 39

How does indirect neurotransmission work?

Answer 39

Mediated by activation of metabotropic receptors Receptor and the channel it controls are distinct Gating of channel is slower

Question 40

Which channels does fast EPSP utilise?

Answer 40

Activation of nicotinic ACh receptors | Conduction of Na+ and K+

Question 41

Which channels does slow EPSP utilise?

Answer 41

Activation of muscarinic G coupled ACh receptors | Close of M-type K+ channels

Question 42

Which is the major excitatory neurotransmitter?

Answer 42

Glutamate

Question 43

What channels will glutamate bind to?

Answer 43

Non-NMDA receptors to bind the agonist kainate or AMPA controlling Na+ and K+ NMDA receptors controlling channels permeable to Na+ , Ca 2+, K+

Question 44

Which mode of transmission will non-NMDA ionotropic receptors (AMPA and kainate) mediate?

Answer 44

Fast excitatory synaptic transmission in the CNS

Question 45

Which mode of transmission will NMDA mediate?

Answer 45

Slow component to excitatory synaptic potential

Question 46

Which ion will NMDA receptors have a high permeability to?

Answer 46

Ca 2+

Question 47

Which drugs act on NMDA receptors?

Answer 47

Ketamine | Psychotomimetic agents such as phencyclidine

Question 48

Which pathway relies on ionotropic and metabotropic glutamate receptors?

Answer 48

Retinal