Lecture 9 : Somatosensory

Question 1

What are primary sensory neurons / primary afferent neurons

Answer 1

First neurons in the sensory pathway carrying info from sensory receptors like skin, muscles or organs, to the CNS.

Their cell bodies are located in the dorsal root ganglia or cranial nerve ganglia.

Question 2

Classification of axon’s of primary afferent neurons

Answer 2

Question 3

Signal Transduction

Answer 3

Question 4

What are tonic (slow / non-adapting) receptors

Answer 4

Strength of stimulus

• Good for posture
• Chronic pain mediated by these receptors

Question 5

What are phasic (fast adapting) receptors

Answer 5

How fast it changes

• vibratory sensations or changes in tactile stimuli, eg. first putting on clothes, you feel them initially then stop noticing
• Good for grip control

Question 6

What are cutaneous sensory receptors

Answer 6

Mechanoreceptors (touch, pressure, vibration)

Thermoreceptors (temperature)

Nociceptors (pain, noxious stimulation)

Question 7

Cutaneous mechanoreceptors

Answer 7

Merkel and meissners are in more superficial layers of skin

Ruffini and Pacinian are in deeper layers

Question 8

Merkel’s Receptor (disk)

Answer 8

Slowly adapting

Question 9

Meissner (tactile) corpuscles

Answer 9

Question 10

Ruffini’s (bulbous) corpuscle

Answer 10

Question 11

Pacinian Corpuscles

Answer 11

Question 12

Hair Follicle Receptors

Answer 12

Question 13

Cutaneous thermoreceptors

Answer 13

Question 14

Thermoreceptor Channels

Answer 14

Question 15

Cutaeceous Nociceptors

Answer 15

Question 16

Proprioception

Answer 16

Question 17

Muscle Spindle

Answer 17

Question 18

2 Central Somatosensory Pathways

Answer 18