lecture 24 - somatic sensation Flashcards

1
Q

What are the two types of senses?

A

Somatic and special

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2
Q

What are somatic senses?

A

Senses detected by generalised receptors found throughout the body

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3
Q

What are special senses?

A

Senses detected by a special/specific organ or structure

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4
Q

What are the 4 key types of somatic sense receptors?

A

Mechanoreceptors, nociceptors, thermoreceptors, chemoreceptors

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5
Q

What do mechanoreceptors sense?

A

Touch, pressure, vibration, proprioception

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6
Q

What do nociceptors sense?

A

Noxious stimuli (pain)

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7
Q

What do thermoreceptors sense?

A

Change in temperature

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8
Q

What do chemoreceptors sense?

A

Chemicals

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9
Q

What senses are considered ‘special senses’?

A

Vision, hearing, balance, taste, smell

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10
Q

What is signal transduction in terms of somatic sensation?

A

When sensory receptors are activated, leading to the opening of ion channels and a change in membrane potential causing a receptor potential which will cause an action potential if the threshold is reached.

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11
Q

How are mechanoreceptors stimulated?

A

By physical forces that distort their plasma membrane, causing mechanically gated ion channels to open.

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12
Q

What are the 3 main types of mechanoreceptors?

A

Proprioreceptors, baroreceptors, tactile receptors

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13
Q

What is an example of a proprioreceptor?

A

Muscle spindles

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14
Q

What do baroreceptors detect?

A

Pressure - e.g. blood pressure

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15
Q

What do tactile receptors sense?

A

Touch, pressure and vibration

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16
Q

In free nerve endings, what type of stimulus is detected by those with myelinated axons?

A

Temperature

17
Q

In free nerve endings, what type of stimulus is detected by those with unmyelinated or thinly myelinated axons?

A

Pain/noxious stimuli

18
Q

What are tonic receptors?

A

Receptors that are continually active (firing APs), with the frequency of APs changing to reflect the intensity of the stimulus.

19
Q

Are tonic receptors slow or fast adapting?

A

Slow adapting

20
Q

What are phasic receptors?

A

Receptors that are normally ‘silent’/inactive, but will respond briefly with APs to changes/stimulus.

21
Q

What are the 4 types of information encoded in sensory stimuli?

A

Modality, Intensity, Location & Duration - (MILD acronym)

22
Q

What is modality in terms of information coding?

A

The type of receptor activated, and therefore the type of sensation.

23
Q

What is intensity in terms of information coding?

A

The stimulus strength, encoded by the frequency of action potential firing and the number of axons activated.

24
Q

What is duration in terms of information coding?

A

The time period over which stimulus exists, encoded by the time period over which action potentials are fired in the afferent neuron.

25
Q

What is location, in terms of information coding?

A

The place in the body where receptors are activated, which is then mapped in the brain (somatosensory cortex)

26
Q

When sensory stimulus intensity is weak, what will occur?

A

Threshold will not be reach, so there will be no response in the afferent neuron.

27
Q

What are muscle spindles?

A

Stretch receptors that signal the length and and changes in length of muscles in response to stretch stimulus. They lie parallel to the main muscle and stretch as muscles lengthens and shorten as they contract