Somatosensory Physiology N19 Flashcards Preview

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Flashcards in Somatosensory Physiology N19 Deck (64)
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1

Sensory Transduction

process by which a stimulus is transformed into an electrical response

2

Sensory unit

one afferent peripheral process with all of its receptor endings and receptors

3

Receptors can be either

specialized endings of afferent neurons or separate receptor cells that signal afferent neurons via chemical messengers

4

Stimulus generates a

graded potential, or receptor potential, in the nerve generating a local current

5

Threshold in an afferent neuron

If threshold is reached, an AP travels to the CNS

6

Increase in graded potential magnitude generates

an increase in AP frequency and an increase in neurotransmitters released at the CNS synapse

7

Increase in graded potential magnitude does not change AP's _____

magnitude

8

Factors that change the receptor potential magnitude

stimulus strength, rate of change of stimulus strength, temporal summation, and adaptation

9

Adaptation refers to

a change in receptor sensitivity due to constant stimuli, resulting in decreased AP frequency despite stimuli

10

Coding

conversion of stimulus energy into a signal that conveys relevant sensory information

11

Stimulus characteristics

location, type of energy, intensity of energy

12

Location of stimulus is determined by

which neuron is activated, each neuron terminates in a specific region of the CNS

13

Stimulus modality

type of sensory receptor a stimulus activates plays the primary role in coding

14

Mechanoreceptors

respond to mechanical stimuli (bending of hair, dee pressure, vibrations, stretch, and superficial touch)

15

Thermoreceptors

sensitive to temperature (cold: 10-38C, warm: 32-45C)

16

Thermal nociceptors

sensitive to cold pain or hot pain

17

Photoreceptors

respond to light of a particular wavelength

18

Chemoreceptors

respond to the binding of particular chemicals to the receptive membrane (internal: gas levels in blood; external: tastebuds on tongue)

19

Nociceptors

respond to stimuli that cause pain (excessive mechanical deformation, excessive temperatures, chemicals) free nerve endings

20

Adequate Stimulus

type of energy to which a particular receptor responds (very sensitive to specific energy form)

21

Sensory stimulation vs sensation

electrical stimulation of a "cold" primary afferent neuron may be perceived as a cold sensation, even though the "cold" thermoreceptor was not stimulated

22

Frequency Coding

the intensity of the stimulus is coded by the frequency of APs (stronger stimulus = greater AP frequency)

23

Population Coding

Stronger stimulus = larger area of receptors activated

24

Threshold

lowest stimulus intensity that a subject can reliably detect (varies by context, experience, fatigue, BUT does not represent a change in the receptor)

25

What would be a situation where the threshold is decreased?

Anticipation

26

What would be a situation where the threshold is increased?

Childbirth, competitive sports

27

Rapidly Adapting Receptors

Respond rapidly at onset/offset of stimulus, but fir slowly or stop during remainder of stimulus. (Important for transient or dynamic stimuli)

28

Slowly Adapting Receptors

Maintain activation throughout stimulus, provide info on static qualities of a slow changing or prolonged event

29

Presynaptic Inhibition

descending inhibitory controls exerted on primary afferent neurons

30

Central control of afferent information

as the AP travels to the cerebral cortex, signals may be modified at synapses