Physiology - Introduction to the Nervous System

Question 1

what is the role of the dendrites?

Answer 1

receives inputs from other neurones and convey signals to the soma

Question 2

what is the role of the cell body of a neurone?

Answer 2

it is the synthetic and metabolic centre of the neurone

integrates incoming electrical signals and conducts them to the axon

Question 3

what happens at the axon hillock?

Answer 3

it is the site of initiation of the action potential

Question 4

what is the role of the axon?

Answer 4

conducts output signals as action potentials to the presynaptic terminal

Question 5

what is anterograde transport?

Answer 5

along an axon from the soma to the presynaptic terminal

Question 6

what is retrograde transport?

Answer 6

along an axon from the presynaptic terminal to the soma

Question 7

what is another name for the neurone cell body?

Answer 7

the soma

Question 8

what is a synapse?

Answer 8

a point of chemical communication between neurones or other cells

Question 9

what can viruses exploit to infect neurones?

Answer 9

the retrograde transport system

Question 10

what are the three components that make up a synapse?

Answer 10

presynaptic terminal
synaptic cleft
postsynaptic membrane

Question 11

what is another name for the processes arising from the soma?

Answer 11

neurites

Question 12

describe a unipolar neurone

Answer 12

one neurite

Question 13

describe a pseudo-unipolar neurone

Answer 13

one neurite that bifurcates

Question 14

describe a bipolar neurone

Answer 14

two neurites

Question 15

describe a multipolar neurone

Answer 15

three or more neurites

Question 16

what are the four functional regions found in most neurones?

Answer 16

input
integrative
conductive
output

Question 17

what happens to the electrical signal in an action potential as it is conducted over a large distance?

Answer 17

they do not decay but stay constant

Question 18

what happens to passive signals as they pass from their site of initiation and why?

Answer 18

they diminish

the nerve cell membrane is leaky meaning current is lost

Question 19

what is the length constant (λ)?

Answer 19

the distance that the current can travel before it diminishes to zero

Question 20

what two factors does the length constant depend on?

Answer 20

membrane resistance (rm) 
axial resistance (ri)

Question 21

what is membrane resistance (rm)?

Answer 21

the membranes ability to resists leakage of current

should be high

Question 22

what is axial resistance (ri)?

Answer 22

the impedance of the current inside the axon

should be low

Question 23

how can the length constant be increased?

Answer 23

increase the ratio of membrane resistance/axial resistance

Question 24

what impact does increasing length constant have on AP conduction velocity?

Answer 24

increases local current spread which increases AP conduction velocity

Question 25

how can you increase passive current spread in an axon?

Answer 25

either decrease axial resistance or increase membrane resistance

Question 26

how can you decrease axial resistance?

Answer 26

increase axon diameter

Question 27

how can you increase membrane resistance?

Answer 27

myelination

Question 28

what cells are responsible for myelination?

Answer 28

Schwann cells in the PNS | oligodendrocytes in the CNS

Question 29

what cell type are Schwann cells and oligodendrocytes?

Answer 29

macroglia

Question 30

describe the presence of Schwann cells around axons

Answer 30

many Schwann cells surround one axon

Question 31

describe the presence of oligodendrocytes around axons

Answer 31

one oligodendrocyte surrounds many axons

Question 32

is conduction faster in a myelinated or non-myelinated axon?

Answer 32

myelinated

Question 33

what is saltatory conduction?

Answer 33

when the AP jumps from one node of ranvier to the next

Question 34

in which axons does saltatory conduction occur in?

Answer 34

myelinated axons

Question 35

what effect do demyelinating disorders have on conduction?

Answer 35

slow down nerve conduction speed

Question 36

name two demyelinating disorders

Answer 36

MS | Guillain Barre syndrome

Question 37

what separates the pre and post synaptic membranes?

Answer 37

synaptic cleft

Question 38

what is found in the synaptic cleft and what does it do?

Answer 38

a matrix of fibrous extracellular protein holds the membranes together

Question 39

where are neurotransmitters stored?

Answer 39

within vesicles in the presynaptic terminal

Question 40

what feature is found in the presynaptic membrane?

Answer 40

active zones where vesicles cluster

Question 41

what feature is found in the postsynaptic membrane?

Answer 41

the postsynaptic density containing neurotransmitter receptors

Question 42

what are the three types of synapses classified by the location of the presynaptic terminal on the postsynaptic cell?

Answer 42

axodendritic axosomatic axoaxonic

Question 43

what is an axodendritic synapse?

Answer 43

axon meets the dendrites

Question 44

what is an axosomatic synapse?

Answer 44

axon meets the soma

Question 45

what is an axoaxonic synapse?

Answer 45

axon meets the axon

Question 46

what are the two functional types of synapse?

Answer 46

excitatory | inhibitory

Question 47

what is the transmitter for excitatory synapses in the CNS?

Answer 47

glutamate

Question 48

what postsynaptic receptors does glutamate bind to?

Answer 48

cation selective glutamate receptors

Question 49

what does glutamate binding cause?

Answer 49

the excitatory postsynaptic potential (epsp)

Question 50

what are the transmitters for inhibitory synapses in the CNS?

Answer 50

GABA or glycine

Question 51

what postsynaptic receptors does GABA/glycine bind to?

Answer 51

anion selective GABA/glycine receptors

Question 52

what effect does GABA/glycine binding have?

Answer 52

inhibitory post synaptic potential (ipsp)

Question 53

what ion channels are opened in response to the epsp?

Answer 53

positive sodium channels causes a depolarisation

Question 54

what ion channels are opened in response to the ipsp?

Answer 54

negative chloride channels causes a hyperpolarisation

Question 55

what are the three main classes of neurotransmitters?

Answer 55

amino acids amines peptides

Question 56

name an amino acid neurotransmitter and where they are released from?

Answer 56

glutamate synaptic vesicles

Question 57

name an amine neurotransmitter and where they are released from?

Answer 57

noradrenaline synaptic vesicles

Question 58

name a peptide neurotransmitter and where they are released from?

Answer 58

CCK secretory vesicles

Question 59

how does a neurotransmitter work directly on an ion channel?

Answer 59

via ionotropic receptors

Question 60

describe an ionotropic receptor

Answer 60

the receptor is an integral part of the channel

Question 61

which is causes faster gating - ionotropic or metabotropic receptors?

Answer 61

ionotropic

Question 62

how does a neurotransmitter work indirectly on an ion channel?

Answer 62

via metabotropic receptors

Question 63

describe a metabotropic receptor

Answer 63

the receptor and the channel it controls are two separate, distinct components