Sensory Nerves Flashcards

1
Q

What is sensory modality?

A

The type of stimulus a receptor normally responds to

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2
Q

What are mechanoreceptors?

A

Sensory receptors stimulated by mechanical stimuli - touch stretch, pressure, deformation.
Detect many stimuli, balance hearing

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3
Q

What are proprioceptors?

A

Mechanoreceptors in joints and muscles that signal info related to body or limb position.

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4
Q

What are nociceptors?

A

Respond to painful stimuli

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5
Q

What is a graded membrane potential change called in a sensory nerve?

A

Receptor or generator potential

Transduction always results in opening/closing of ion channels

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6
Q

Where are action potentials produced from the receptor potential?

A

Wherever the membrane has voltage gated ion channels

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7
Q

When do you get a higher frequency of action potentials?

A

larger stimulus causes larger receptor potential
Can activate more receptors

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8
Q

What is meant by adaptation of a mechanoreceptor?

A

When mechanoreceptor adapts to maintained stimulus and only signals for a change or novel event

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9
Q

Give an example of a sensory receptor that does not adapt?

A

Nociceptor, important to detect painful stimuli

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10
Q

What is a pacinian corpsucle responsive to?

A

Vibration and pressure

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11
Q

Describe the structure of a pacinian corpuscle

A

Myelinated nerve
Naked nerve ending, enclosed in CT capsule
Capsule contains layered membrane lamellae separated by fluid

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12
Q

How are action potentials generated from a pacinian corpsucle

A

Mechanical stimuli deforms capsule and nerve ending, causing ion channels to open, - generator potential then action potential.

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13
Q

How is the pacinian corpsucle capable of rapid adaptation?

A

Fluid redistribution of corpsucle rapidly dissipates stimulus, nerve ending no longer stretched

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14
Q

What happens to the pacinian corpsucle when the stimulus is withdrawn?

A

Capsule springs back - AP fired again

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15
Q

What type of structure is the pacinian corpuscle?

A

Non-neural accessory structure

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16
Q

What is the receptive field?

A

The Area that a stimuli will activate a sensory neurone

17
Q

What does the ability to tell apart two points on the skin depend on?

A

Size of receptive field
Neuronal convergence

18
Q

What is meant by convergence?

A

When multiple presynaptic neurones synapse with fewer post synaptic neurones

19
Q

What does convergence allow?

A

Allows sub threshold stimuli to sum at the secondary neurone forming and initiating action potentials

20
Q

How can we locate a stimulus so precisely?

A

Lateral inhibition of sensory neurones at the edge of stimulus