Introduction to Neurons, Nerve Conduction and Synaptic Transmission Flashcards

1
Q

What do dendrites do?

A
  • Receive input from other neurones
  • Convey graded electrical signals to the soma
  • Add surface area to the neurone
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2
Q

How are electrical signals conveyed to the soma?

A

Graded

PASSIVELY

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3
Q

What is the soma aka?

A

Perikaryon

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4
Q

What is the soma the centre of?

A

Synthesis and metabolism

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5
Q

What does the soma contain?

A

Nucleus
Ribosomes
Mitochondria
ER

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6
Q

What does the soma integrate?

A

Incoming signals that are conducted passively to the axon hillock

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7
Q

What occurs at the axon hillock?

A

Initiation of the ‘all or none’ action potential

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8
Q

What does the axon do?

A

Conducts output signals as action potentials to other cells/neurons
Mediate transport materials between the soma and the presynaptic terminal

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9
Q

What can viruses do to a neuron? Give examples of such viruses.

A

Affect retrograde transport

Herpes, Polio, Rabies

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10
Q

What direction does the axon transport materials in?

A

ANTEROGRADE
or
RETROGRADE

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11
Q

Dendrites can be either…..

A

Apical or Basal

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12
Q

Unipolar

A

1 neutrite

e.g PNS

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13
Q

Pseudounipolar

A

1 neutrite that bifurcates

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14
Q

Bipolar

A

2 neutrites

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15
Q

Multipolar

A

3/+ neutrites

e.g LMN

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16
Q

How many functional regions do most neurones have?

A

4

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17
Q

Name the 4 functional regions of a neurone.

A

Input
Integrative
Conductile
Output

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18
Q

What causes the upstroke of an AP in neurones?

A

The opening of voltage activated Na+ channels

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19
Q

What is ‘over-shoot’?

A

A brief period when polarity is reversed to inside positive

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20
Q

What causes the downstroke of an AP in neurones?

A

The opening of voltage activated K+ channels

and the closure of activated Na+ channels

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21
Q

Why does undershoot occur?

A

Because K+ channels don’t close immediately once membrane potential is reached

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22
Q

The nerve cell membrane is ‘leaky’. Explain this.

A

Not a perfect insulator

Passive signals don’t spread far from their site of origin due to current loss across the membrane

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23
Q

The amplitude of an AP is….

A

CONSTANT

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24
Q

Current leaks back to what across the membrane resistance (rm)?

A

Extracellular space

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25
Q

What does current leaking to the extracellular space generate?

A

Generates a potential change (Vm)

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26
Q

For a given current (I), Vm increases linearly with rm

A

TRUE

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27
Q

Describe the process of membrane potential change.

A

PASSIVE

Decays exponentially with distance

28
Q

What does the distance over which current spreads depend on?

A

Membrane resistance (rm)
AND
Axial resistance of the axoplasm (ri)

29
Q

What decreases resistance?

A

Increasing diameter

Decreasing distance of travel

30
Q

What is passive conduction a factor in?

A

The propagation of an AP

31
Q

What is the relationship between the length constant and local current spread?

A

The longer the length constant (λ) the greater the local current spread

32
Q

What does greater local current spread increase?

A

AP conduction velocity

33
Q

What does increasing axonal diameter do?

A

Decreases ri

34
Q

What does adding myelin do?

A

Increases rm

35
Q

Schwann cells surround a …… axon

A

SINGLE

36
Q

Oligodendrocytes surround …. axons

A

MANY

37
Q

Conduction in myelinated axons is THE SAME AS/ FASTER than in non-myelinated
axons of the same diameter

A

FASTER

38
Q

Where do AP’s ‘jump’ from?

A

One node of ranvier to another

39
Q

What do you find clusters of at NOR?

A

Voltage activated Na+ channels

40
Q

Name 2 demyelinating disorders?

A

MS

Guillian-Barre Syndrome

41
Q

Name the 3 types of synapse.

A

Axodendritis
Axosomatic
Axoaxonic

42
Q

Name the 3 types of synapse in order from most common to least common.

A

Axodendritis
Axosomatic
Axoaxonic

43
Q

What neurotransmitter is most frequently used for EXCITATORY synapse?

A

Glutamate

44
Q

What does glutamate activate?

A

Activates postsynaptic, cation selective, ionotropic, glutamate receptors.

45
Q

What is the outcome of glutamate activation?

A

This generates a local, graded excitatory (depolarizing) response: the excitatory postsynaptic potential (epsp).

46
Q

What does glutamate activate?

A

Activates postsynaptic, CATION selective, ionotropic, glutamate receptors.

47
Q

What neurotransmitter is most frequently used for INHIBITORY synapse?

A

-aminobutyric acid (GABA), or glycine

48
Q

What does y-aminobutyric acid (GABA) and glycine activate?

A

Activate postsynaptic, ANION selective, ionotropic, GABAA, or glycine, receptors.

49
Q

What do the INHIBITORY neurotransmitters generate?

A

This generates a local, graded, inhibitory (hyperpolarizing) response: the inhibitory postsynaptic potential (i.p.s.p.)

50
Q

What are the major amino acid neurotransmitters in the CNS?

A

Glutamate, glycine and GABA

51
Q

What are pre and post synaptic membranes separated by?

A

Synaptic cleft

52
Q

What is the synaptic cleft composed of?

A

A matrix of extracellular proteins

53
Q

What are the membrane differentiations i) presynaptically? Ii) postsynaptically?

A

i) the active zones around which vesicles cluster

ii) the postsynaptic density containing neurotransmitter receptors

54
Q

What is the information transfer sequence in the CNS?

A
  1. Electrical
  2. Chemical
  3. Electrical
55
Q

Many inputs converge upon a neurone to determine its input is know as?

A

SPATIAL summation

56
Q

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

A

TEMPORAL summation

57
Q

Physiologically, spatial and temporal summation isolated/complementary processes

A

COMPLEMENTARY

58
Q

Name the 3 main types of neurotransmitter substance.

A

Amino acids
Amines
Peptides

59
Q

What type of neurotransmitter are released from synaptic vesicles?

A

Amino acids and amines

60
Q

What type of neurotransmitter is released from secretory vesicles?

A

Peptides

61
Q

What can Glutamate, GABA, glycine, acetylcholine, and 5-HT activate? What do these mediate?

A

Ionotropic ligand-gated ion channels (LGICs)

Mediate fast neurotransmission

62
Q

GPCRs mediate relatively slow neurotransmission

A

TRUE

63
Q

Glycine and Glutamate only occur in neurones

A

FALSE

They occur in all other cells

64
Q

What must be specifically synthesized by neurones that release glycine and glutamate? What does this require?

A

GABA and amines

They need specific enzymes

65
Q

What is neurotransmitter concentrated in the vesicles by?

A

Transporters embedded in the vesicle membrane

66
Q

At the terminal, what do enzymes mediate?

A

Synthesis of neurotransmitter from precursor substances within the cytoplasm

67
Q

Outline the process of synthesis and storage of peptide neurotransmitters

A
  1. Synthesis of precursor peptide by ribosomes in the RER
  2. Cleavage of precursor in Golgi by active neurotransmitter
  3. Secretory vesicles budd off from Golgi
  4. Secretory granules are transported to the presynaptic terminal by fast axoplasmic transport via microtubules