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Neuro > Axonial transmission > Flashcards

Axonial transmission Flashcards

1
Q

What is a neuron?

A
  • basic cellular unit of the neuron
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2
Q

What components makes up a neuron?

A
  1. ) Dendrites
  2. ) Cell body/soma
  3. ) Axon
  4. ) Presynaptic terminal
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3
Q

What is axonal transmission

A

Transmission of information from location A to location B

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4
Q

What is synaptic transmission

A

Integration/processing of information and transmission between neurons

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5
Q

What is an example of axonal transmission failure

A

Multiple sclerosis

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6
Q

Key symptoms of multiple sclerosis

A
  • eye movements: uncontrolled
  • speech: stunted
  • paralysis: partial/complete
  • tremor
  • co-ordination: lost
  • weakness: tired
  • sensory: numbness
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7
Q

Prognosis of MS

A
  • initial symptoms: slight with remission

- difficult to diagnose

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8
Q

Who gets MS

A
  • young adults 20-40
  • temperate zones
  • areas with high standards of sanitation
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9
Q

What is the neurons resting potential

A

It is -70 mV

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10
Q

Why is it this figure?

A
  • neuronal cell membranes are semi permiable
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11
Q

What ions can/can’t pass

A
  • Electrically charged K+ and Cl- can cross readily
  • Na+ crosses with difficulty
  • Large organic proteins (-ve charge) can’t pass)
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12
Q

What forces are at work here?

A
  1. ) Diffusion

2. ) Electrostatic attraction/repulsion

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13
Q

Ions

A
  1. ) A-: restricted to inside of cell
  2. ) Na+: mostly outside neuron. Membrane quite impermeable to Na+.
  3. ) K+: mostly inside neuron
  4. ) Cl-: mostly outside neuron
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14
Q

Sodium-potassium pump

A
  • Active process to transport Na+ ions out of neuron and K+ in
  • Three Na+ for every two K+
  • Require energy supplied by ATP
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15
Q

What is the action potential

A
  • Neuron fires: sudden pulse where the negative resting potential is temporarily reversed
  • Transmits information: the message
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16
Q

Events within the action potential

A

Depolarization & threshold
Reversal of membrane potential
Repolarisation to resting potential
Refractory period

17
Q

Describe what takes place during an action potential

A
  • neurotransmitters initiate changes at the dendrites of neurons: membrane permeability changes
    Neurotransmitters activate receptors on dendrites / soma
    Receptors open ion channels
    Ions cross plasma membrane, changing the membrane potential
    The potential changes spread through the cell
    If the potential changes felt at the axon hillock are positive (+mV), and large enough, an action potential is triggered
18
Q

Depolaisation

A
  • Excitatory neurotransmitters depolarise the cell membrane
  • Increases probability of AP being elicyed
    Cause an EPSP
19
Q

Hyperpolarisation

A
  • inhibitory neurotransmitters hyperpolarise the cell membrane
  • decreases probability of an A.P being elicted
  • causes an IPSP
20
Q

What is temporal summation

A

tWO THINGS don’t occur at quite the same time. They summate and become bigger

21
Q

What is passive conduction

A
  • voltage changes spead away from point of origin

- whether AP is generate depends on what reaches the axon hilock

22
Q

The AP

A
  • ESPs begin to depolarise cell membrane
  • Threshold: -60mV. When threshold is reaches Na+ channels open and polarity reverses to +30mV inside
  • Membrane potential reverses with the inside going positive
  • Voltage gated Na+ channels close so K+ channels open
  • This restores resting membrane potential
23
Q

What are voltage gated channels

A
  • These are channels that are opened by detecting opposite polarity in an adjacent bit of membrane
  • voltage changes control the ion channels which control the voltage changes
  • the AP is self perpetuating
24
Q

What speeds up axonal conduction

A

Myelination

25
Q

Propagation of action potential with myelinated axons

A
  • There is decremental conduction between nodes

- This is saltatory conduction

26
Q

Propagation of AP without myelinated axons

A
  • have signal loss due to lack of insulation
  • slow due to time to activate each channel
  • mainly short axon interneurons
27
Q

Synaptic transmission: what happens when action potential reaches terminal

A
  • triggers voltage gated Ca2+ channels to open.
  • Get release of Ca2+ ions
    They get released from their vesicles by fusing with the presynaptic membrane and it exocytoses
    Binds to receptors on the postsynaptic membrane
28
Q

What is acetylcholinesterase

A

Is the nsame of the enzyme that breaks down neurotransmitter acetylcholine
- The neurotransmitter get enzyme degradation to break it down

29
Q

What is novichok

A

It is an AChE inhibitor

30
Q

What are the 5 processes of synaptic transmission

A
  1. ) Manufacture: intracellular biochemical processes
  2. ) Storage: vesicles
  3. ) Release: by action potential
  4. ) Interact with post-synaptic receptors: diffusion across the synapse
  5. ) Inactivation: break down/re-uptake
31
Q

Examples of fast neurotransmitters

A
  1. ) Acetylcholine
  2. ) Glutamate
  3. ) Gamma-aminobutyric acid
32
Q

Examples of neuromodulators

A
  1. ) Dopamine
  2. ) Noradrenalin
  3. ) Serotonin
33
Q

Examples of local anaesthetic

A

Procaine and lignocaine

34
Q

How does local anaestetic work?

A
  • Na+ channels blockers

- Blocks progress of action potential

35
Q

ACh

A
  • transmitter at te neuromuscular junction
36
Q

What is ACh affected by

A

1.) Cigarettes
2.) Poison
3>) Spider toxins
4.) Nerve gas

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