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SFI Test 2 > Sensory Systems > Flashcards

Sensory Systems Flashcards

1
Q

What is the common purpose of sensory systems?

A

Provide information about external or internal environment, for generation of adaptive behavior

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2
Q

What is transduction?

A

Convert physical signal (energy) into neural signal

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3
Q

What is encoding?

A

Represent qualitative and quantitatie aspects of stimulus

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4
Q

What is perception?

A

Conscious awareness of stimulation

Doesn’t have to happen, e.g. blood pressure

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5
Q

What is the modality of a stimulus?

A

Quality or type of energy which is transduced

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6
Q

What are the five basic modalities of sensation?

A

Somatosensation

Vision

Audition

Olfaction

Gustation

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7
Q

What is an adequate stimulus?

A

Type of energy that activates a specific receptor at lowest energy level

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8
Q

What is intensity?

A

The strength of a stimulus

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9
Q

What is sensory threshold?

A

The lowest intensity which can be detected reliably (50% of the time)

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10
Q

What is the relationship between threshold and sensitivity?

A

Threshold is inversely related to sensitivity

Threshold is not fixed

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11
Q

Which direction does a decrease in sensitivity shift an intensity-response curve? Increase?

A

Decrease - shifts curve to the right (raises threshold)

Increase - shifts curve to the left (lowers threshold)

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12
Q

What is duration?

A

Length of stimulation

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13
Q

What is characteristic of slowly adapting receptors?

A

Will continue to fire as long as stimulus is present at fixed level

Provides information about stimulus duration

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14
Q

What is characteristic of rapidly adapting receptors?

A

Will fire in response to a change in stimulus intensity

Provides information about the dynamic aspects of a stimulus

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15
Q

What is a receptive field?

A

Specific spatial location where stimulus energy is effective in stimulating a receptor

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16
Q

What is the mechanism of a mechanoreceptor?

A

Tranduces physical energy (membrane deformation) into neural activity

Linked to membrane or cytoskeleton in some way

Cation channel permeable to Na and K that depolarizes the receptor cell

17
Q

What are thermal receptors?

A

Transient Receptor Potential (TRP channels) channels that are thermally stimulated (can be stimulated by other means)

Cation channels that vary in ion permeability depending on channel type

18
Q

What is the difference between cold and warm receptors?

A

Cold: TRP channels that are activated at low temps (12-35)

Warm: TRP channels activated by high temperatures

19
Q

What is another type of stimulus for thermally activated TRP channels?

A

Chemical

Cold: menthol (mint)

Warm: capsaicin

20
Q

What are thermal nociceptors?

A

Pain receptors that are activated by extremes of heat or cold (<12C or >47C)

21
Q

What is receptor potential?

A

Sensory transduction causes channel opening and creates a graded potential

Fewer channels open: small receptor potential

More channels open: bigger receptor potential

22
Q

What must happen to trigger an action potential?

A

The capacitive current created by the receptor potential must depolarize the initial segment of the axon to threshold

23
Q

How is the intensity of a stimulus coded?

A

Frequency coding

Low intensity causes low fire rate

High intensity causes high firing rate

24
Q

How is the duration of a stimulation coded?

A

Encoded by the length of an action potential train (duration of transmitter release onto the second order neuron)

25
Q

What is adaptation?

A

Reduced output despite sustained stimulation

Caused by altered sensory transduction or change in membrane ion conductance

26
Q

What are two ion conductance adaptation mechanisms?

A

Inactivation of inward currents (Na or Ca channels)

Activation of outward currents (Ca activated K channel)

27
Q

What is a calcium-activated potassium channel?

A

Needed for slow adaptation

Increase in cytoplasmic Ca (due to HVA Ca channels) causes the channel to open

Additional K conductance causes the membrane potential to “sag” back towards resting level, reduced rate of action potential firing

28
Q

What are the functional zones of sensory receptors?

A

Transduction - sensory channels

Integration (trigger) - cation channels, Ca-activated K channels

Conduction - axon

Transmission - axon terminal

SFI Test 2 (9 decks)

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