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2.1 BRS Neurology > Nervous Cells and Junctions > Flashcards

Nervous Cells and Junctions Flashcards

1
Q

What are the 4 types of neurone?

A
  1. Unipolar —> 1 axonal projection
  2. Pseudounipolar —> 1 divides in 2
  3. Bipolar —> 2
  4. Multipolar —> many
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2
Q

What are the 3 types of multipolar neurones?

A
  1. Pyramidal cells
  2. Purkinje cells (tree) - GABA neurons in cerebellum
  3. Golgi cells (star) - GABA neurons in cerebellum
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3
Q

What 3 features do all nervous cells have?

A
  1. Soma = body
    • nucleus, ribosomes, neurofilaments
  2. Axon = nerve fibre
    • origin = axon hillock, branches = collaterals
    • myelinated
  3. Dendrites = branches of body
    • receive signals
    • unmyelinated
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4
Q

What are the 3 components of the soma?

A
  1. Nucleus
  2. Ribosomes
  3. Neurofilaments
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5
Q

What are the 5 types of nervous cells and their functions/features?

A
  1. Neuron
    • electrical transmission
  2. Oligodendricyte
    • glial cells —> produce myelin
  3. Astrocyte
    • most abundant cells in CNS
    • connect to blood vessels
  4. Microglia
    • nervous macrophages
  5. Ependyma
    • epithelial cells lining ventricles
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6
Q

Which 4 ions are important in neurotransmission?

A

Na+, K+, Ca2+, Cl-

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7
Q

What are the extracellular vs intracellular concentrations of each 4 ions across an axon membrane?

A
  1. Na+: 140 vs 10 mM
    • high outer
  2. K+: 4 vs 150
    • high inner
  3. Cl-: 120 vs 5
    • high outer
  4. Ca2+: 2 mM vs 0.1 µM
    • gradient
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8
Q

What is the range for RMP?

A

-40 to -90 mV

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9
Q

How is an AP generated?

A
  • VGSCs open —> Na+ influx —> depolarisation
  • VGKCs open (slower) —> K+ efflux —> repolarisation
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10
Q

How is a RP restored?

A

Na+/K+ ATPase:

  1. Resting configuration
    • Na+ enter —> phosphorylation (ATP) —> Na+ out
  2. Active configuration
    • Na+ all out —> K+ enter
  3. Resting configuration
    • K+ in
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11
Q

What type of conduction occurs across an axon and how?

A

Saltatory conduction (cable transmission)
- myelin —> nodes of ranvier —> AP jumps across gaps

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12
Q

What are the 4 steps of synaptic transmission?

A
  1. AP propagation
    • VGSCs open —> Na+ influx —> depolarisation —>
      AP along axon —> VGKCs open —> K+ efflux —>
      repolarisation
  2. NT release
    • AP opens VGCCs at pre-synaptic terminal —> Ca2+
      influx —> NT vesicle exocytosis
  3. Post-s receptor activation
    • NT bind to post-synaptic receptors
  4. NT reuptake
    • NT dissociate from receptors —> metabolise by
      enzymes in synapse or recycles by transporter
      proteins
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13
Q

Which 2 types of communication occur at a synapse?

A

Autocrine
Paracrine

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14
Q

What are the 3 types of synapses?

A
  1. Axodendritic
  2. Axosomatic
  3. Axoaxonic
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14
Q

What is a neuromuscular junction?

A

Junction between axon terminal and muscle membrane —> unidirectional chemical communication between nerve and muscle

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15
Q

Which type of communication occurs at a neuromuscular junction?

A

Paracrine

16
Q

What is a miniature EPP?

A

EPP change by 1 ACh vesicle —> not enough to generate AP

16
Q

How does a nervous impulse cause muscle contraction? (3)

A
  1. AP across axon —> Ca2+ enter pre-synaptic
    terminal
  2. ACh released into synapse
  3. ACh bind to nAChRs on skeletal muscle —> change
    EPP (muscle cell depolarisation)
17
Q

How does excitation-contraction coupling occur? (3)

A
  1. nAChR activated (excitation) —> depolarisation —>
    AP in muscle cell
  2. AP travel through T-tubules —> to sarcoplasmic
    reticulum
  3. Sarcoplasmic reticulum release Ca2+ —>
    contraction
18
Q

What is the location, function and effect of sarcoplasmic reticulum?

A

Location: surround myofibrils
Function: Ca2+ storage and release (depolarisation)
Effect: Ca2+ release —> myofibril and muscle
contraction

19
Q

What are 3 examples of disorders of neuromuscular junctions?

A
  1. Botulism
    • BTx (toxin) —> irreversible disruption to ACh
      release from pre-synaptic nerve
  2. MG (Myasthenia Gravis)
    • autoimmune
    • antibodies against AChRs —> fatigable weakness
  3. LEMS (Lambert-Eaton Myasthenic Syndrome)
    • autoimmune
    • antibodies against VGCCs

2.1 BRS Neurology (13 decks)

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