Lecture 17 Sensory Systems (including physiology of pain) Flashcards Preview

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Flashcards in Lecture 17 Sensory Systems (including physiology of pain) Deck (19)
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1
Q

Receptor that senses light touch

A

Tactile (Meissner’s) Corpuscle

2
Q

Receptor that senses touch

A

Tactile (Merkel’s) Corpuscle

3
Q

Receptor that senses pain

A

Free nerve ending nociceptor

4
Q

Receptor that sense deep pressure

A

Lamellated (Pacinian_ Corpuscle

5
Q

Receptor that senses warmth

A

Ruffini corpuscle

6
Q

What encodes the intensity of the stimulus

A

The frequency of the action potentials

7
Q

What encodes the location of the stimulus

A

The receptive field

8
Q

Where is the receptor potential integrated at

A

The trigger zone

9
Q

Cutaneous sensation is mediated by 3 types of primary afferent fibres what are they?

A

– Aβ = large myelinated (30-70m/s) touch, pressure, vibration
– Aδ = small myelinated (5-30m/s) cold, “fast” pain, pressure
– C = unmyelinated fibres (0.5-2m/s) warmth, “slow” pain

10
Q

Proprioception is mediated by what 2 types of primary afferent fibres

A

– Aα & Aβ eg muscle spindles, golgi tendon organs etc

11
Q

Afferent fibres of mechanoreceptors

A

(Aα & Aβ) fibres

12
Q

Describe the path of the Mechanoreceptive (Aα & Aβ) fibres

A

– project straight up through ipsilateral dorsal columns
– synapse in cuneate & gracile nuclei
– the 2nd order fibres cross over midline (decussate) in the brain stem & project to reticular formation, thalamus and cortex

13
Q

Name the Thermoreceptive & nociceptive fibres

A

(Aδ & C)

14
Q

Describe the path of the Thermoreceptive & nociceptive (Aδ & C) fibres

A

– synapse in the dorsal horn
– the 2nd order fibres cross over the midline in the spinal cord
– project up through the contralateral spinothalamic (anterolateral) tract to reticular formation, thalamus and cortex

15
Q

What would be the consequence of damage to the dorsal columns

A

– causes loss of touch, vibration, proprioception below lesion on ipsilateral side

16
Q

What would be the consequence of damage to the anterolateral quadrant

A

– causes loss of nociceptive & temperature sensation below lesion on contralateral side

17
Q

Define Adaption

A

gradual decrease over time in the responsiveness of the sensory system to a constant stimulus. Can be rapid or slow

18
Q

Define Lateral Inhibition

A

– activation of one sensory input causes synaptic inhibition of its neighbours
– gives better definition of boundaries
– cleans up sensory information

19
Q

Singal transduction in Nociceptors are activated by what

A

low pH, heat (via ASIC, TRPV1 etc)

-local chemical mediators (eg bradykinin, histamine, prostaglandins)

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