L9.1. Somatosensory System

Question 1

What are the type of sensations?

Answer 1

superficial, deep, visceral, special senses

Question 2

What are the types of receptors?

Answer 2

mechanoreceptor, thermoreceptors, nociceptor, electromagnetic receptors, chemoreceptors

Question 3

What receptor responds to changes in light intensity and wavelength?

Answer 3

electromagnetic receptors

Question 4

What are the two anatomical types of receptors?

Answer 4

encapsulated and non-encapsulated

Question 5

What is the most abundant type of nerve endings?

Answer 5

free nerve endings

Question 6

What is the most common type of free nerve endings?

Answer 6

nociceptors

Question 7

What are the functions of free nerve endings?

Answer 7

1. pain (most common)
2. crude touch (non-discriminating)
3. pressure
4. cold and heat
5. tickle

Question 8

What is the main type of tactile end organ that senses gentle touch?

Answer 8

Merkel Discs

Question 9

Merkel discs are responsible for ______ touch, discriminative touch, and ________ pressure which allows pinpointing of the stimulus’ location.

Answer 9

light, light

Question 10

Receptor fields of Merkel discs are very small with well-defined borders. What is the implication?

Answer 10

sensitive in detecting edges of the objects

Question 11

Is the Merkel disc slow or fast adapting?

Answer 11

slow

Question 12

What stimulates hair follicle receptors?

Answer 12

bending of hair

Question 13

What is the function of Meissner’s Corpuscles?

Answer 13

Fine touch and Pressure, and Low-Frequency Vibration

Question 14

When an object is about to slip ones hand, which receptor is responsible for sensing it?

Answer 14

Meissner’s Corpuscles - it’s responsive to fine touch, rapidly adapting, with small and well defined borders

Question 15

What is the function of Pacinian Corpuscles?

Answer 15

detect pressure (P = pacinian)

Question 16

What mechanoreceptor detects skin stretch and deformation within the joints? This may also detect warmth.

Answer 16

Ruffini Corpuscles

Question 17

Which receptor detects the rate and speed of stretch?

Answer 17

Neuromuscular Spindles

Question 18

What is the function neurotendinous spindles?

Answer 18

provides CNS about muscle tension

(it has an inhibitory reflex to inhibit muscle contraction to prevent muscle tears)

Question 19

What receptors are “touch receptors”?

Answer 19

Meissner’s, Merkel’s, Hair Cells

Question 20

What receptors detects cold temperature?

Answer 20

Krause’s end-bulbs

Question 21

What receptor detects warm temeprature?

Answer 21

Ruffini Corpuscles

Question 22

What receptor detects pain?

Answer 22

Free Nerve Endings

Question 23

What receptors are “proprioceptors”?

Answer 23

Pacinian corpuscles, Joint Receptors, Muscle Spindles, Golgi Tendon Organs, Free Nerve Endings (pain)

Question 24

Which somatosensory pathway carries sensations of crude touch, pain, and temperature?

Answer 24

ventrolateral system

Question 25

Which tracts are part of the ventrolateral system and what are their functions?

Answer 25

Anterior Spinothalamic Tract: Crude Touch & Pressure Lateral Spinothalamic Tract: Pain and Temperature

Question 26

What does "nociceptive" mean"?

Answer 26

sensitive to noxious stimuli

Question 27

What is the increased sensitivity to pain?

Answer 27

Hyperalgesia

Question 28

What is the decreased sensitivity to pain?

Answer 28

Hypoalgesia

Question 29

What is Analgesia?

Answer 29

absence of pain perception

Question 30

What are the two ascending pathways and what are their functions?

Answer 30

spinothalamic: sharp stabbing pain spinoreticulothalamic: deep, poorly localized, burning pain

Question 31

This is the hyperexcitability of Dorsal Root Ganglion neurons due to mutations of sodium channels which alter ion channel function.

Answer 31

Channelopathies

Question 32

Hyperexcitability of Dorsal Root Ganglion Neurons following nerve injury.

Answer 32

Neuropathic pain

Question 33

Perception of non-noxious stimuli as painful

Answer 33

Allodynia

Question 34

Perception of a mildly unpleasant stimulus as very painful

Answer 34

Hyperpathia

Question 35

What theory states that transmission of pain signals can be modulated at the spinal cord level by non-painful inputs?

Answer 35

Gate Control Theory

Question 36

All pain travels to which fiber?

Answer 36

A-delta fiber

Question 37

Motion detection is transmitted by which fiber?

Answer 37

A-beta fiber

Question 38

What is the function of C-fibers?

Answer 38

detects constant pressure or chronic pain (C for constant and chronic)