Lecture 6: basic physiology of nerve cells Flashcards

1
Q

What can affect the presynaptic neuron?

A

Stimuli on the dendrites and cell body (the soma)

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2
Q

What area generates the action potential?

A

The axon hillock

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3
Q

What response do dendrites and the cell body (soma) make when affected by stimuli?

A

Graded responses that alter membrane potential (depolarise or hyperpolarise)

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4
Q

At what point is an action potential generated?

A

If the hillock reaches threshold

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5
Q

What potential does excitatory neurons produce?

A

Excitatory post-synaptic potentials

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6
Q

What potential does inhibitory neurons produce?

A

Inhibitory post-synaptic potentials

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7
Q

What type of response can action potentials have?

A

All or nothing response

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8
Q

What are the thin, ribbon-like cells that commonly wrap around axons called?

A

Schwann cells

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9
Q

What is the effect of the layers of myelin that make a shwann cell called?

A

Myelination

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10
Q

What are the gaps between Schwann cells where the axon membrane touches the extracellular fluid called?

A

Nodes of Ranvier

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11
Q

How fast does an AP travel down a myelinated axon?

A

Approx. 150m/s

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12
Q

How fast does an AP travel down an unmyelinated axon?

A

0.5 to 10 m/s

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13
Q

The wider the axon, the ____ the AP

A

Faster

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14
Q

What type of neuron are Aalpha?

A

Motor neurons/proprioceptors, muscle spindles, golgi, tendon, organs

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15
Q

What type of neuron are Abeta?

A

touch, mechanical touch/pressure

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16
Q

What type of neuron are Adelta?

A

Pain (fast) temp

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17
Q

What type of neuron are C?

A

Pain (slow) temp, itch

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18
Q

What happens if myelination breaks down?

A

Signals no longer work in concert, results in multiple sclerosis

19
Q

What are the two main types of cell-cell propagation?

A

Electrical synapse, chemical synapse

20
Q

Why do electrical synapses act directly and quickly?

A

Gap junctions allow AP to continue from one cell to the next

21
Q

What is a limitation of electrical synapses?

A

Does not allow much variation in the post-synaptic response

22
Q

What molecules are released into the synaptic cleft in chemical synapses?

A

Neurotransmitters

23
Q

What triggers AP on the postsynaptic neuron after a chemical synapse?

A

Binding of neurotransmitters to the post synaptic membrane (can also rebind to trigger more)

24
Q

What is the first step of voltage-activated Ca2+ channels when an action potential arrives at the synaptic terminal?

A

Depolarisation opens the voltage-activated Ca2+ channels

25
Q

What happens when the Ca2+ channels initially open after depolarisation?

A

[Ca2+] inside is low, so concentration and electrical gradients cause Ca2+ to flow inwards

26
Q

Why are calcium ions important in neurotransmitter translocation?

A

Ca2+ dependent phosphorylation of v-SNARE proteins

27
Q

What happens to vesicles associated with the docking region of the plasma membrane?

A

It is then primed through synaptic t-SNARE proteins followed by Ca2_ stimulated fission of vesicle with plasma membrane

28
Q

Where are small neurotransmitters (such as acetylcholine and noradrenaline) synthesised?

A

Synaptic bulb, then packaged into vesicles

29
Q

Where are large (protein) neurotransmitters synthesised?

A

In the cell body, transported inside vesicles down axon to synapse

30
Q

What is adrenaline?

A

Fight or flight neurotransmitter

31
Q

What is noradrenaline?

A

Concentration neurotransmitter

32
Q

What is dopamine?

A

Pleasure neurotransmitter

33
Q

What is serotonin?

A

Mood neurotransmitter

34
Q

What is GABA?

A

Calming neurotransmitter

35
Q

Criteria for neurotransmitter discovery: the chemical must be produced within a…

A

Neuron

36
Q

Criteria for neurotransmitter discovery: the chemical must be found within a…

A

Neuron

37
Q

Criteria for neurotransmitter discovery: when a neuron is stimulated/deploarised, a neuron must…

A

Release the chemical

38
Q

Criteria for neurotransmitter discovery: when a chemical is released/applied, it must…

A

Act on a post-synaptic receptor and cause a biological effect

39
Q

Criteria for neurotransmitter discovery: after a chemical is released, it must be able to be

A

inactivated, either through reuptake or by enzyme that stops the action

40
Q

What type of channels are invovled in producing excitatory post-synaptic potentials?

A

Glutamate-gated channels

41
Q

How do glutamate-gated channels generate depolaization of the post-synaptic neuron?

A

Cause a net influx of Na+

42
Q

What channels are involved in producing inhibitory postsynaptic potentials?

A

GABA and glycine-gated channels

43
Q

How do GABA and glycine-gated channels hyperpolarise the postsynaptic neuron?

A

Cause an net influx of Cl-