Somatosensory 1 & 2

Question 1

How many pairs of spinal nerves and cranial nerves do we have?

Answer 1

31 pairs of spinal
12 pairs of cranial

Question 2

Define somatic sensory system

Answer 2

Sensation as it relates to the body

Question 3

What are examples of somatic sensory?

Answer 3

Touch
pressure
vibration
limb position
heat
cold
pain

Question 4

How are somatic sensory signals sent?

Answer 4

Transduced by receptor within skin or muscles and conveyed to a variety of CNS targets

Question 5

___ receptors are for fine/light touch, vibration and pressure

Answer 5

Mechano receptors

Question 6

___ receptor is for proprioception

Answer 6

Proprioceptors

Question 7

___ receptor is for painful stimuli and coarse touch

Answer 7

Nociceptors

Question 8

___ receptor is for changes in temperature

Answer 8

Thermoreceptors

Question 9

Define somatosensory afferents

Answer 9

Convey information from the skin surface to central circuits

Question 10

___ in the dorsal root ganglia give rise to processes that receive information from the skin and send process into the spinal crod

Answer 10

Pseudounipolar neurons

Question 11

Neurons in the dorsal root ganglia are often called

Answer 11

pseudounipolar

Question 12

A __ neuron pathway is involved w/ sensation

Answer 12

3

Question 13

What is the relay center of the brain?

Answer 13

Thalamus

Question 14

1st neuron in the neuron pathway is

Answer 14

Dorsal root ganglia

Question 15

___ is the process of converting the energy of a stimulus into an electrical signal

Answer 15

sensory transduction

Question 16

afferent fibers are often encapsulated by specialized receptor cells called

Answer 16

mechanoreceptors

Question 17

afferent fibers w/o specialized receptors are

Answer 17

free nerve endings

Question 18

what are free nerve endings important for?

Answer 18

sensation of pain

Question 19

Describe stretch gated channels

Answer 19

mechanical stimulus puts pressure on the encapsulation which causes channels to stretch and Na+ rushes in
- deformation of pacinian corpuscle stretches the membrane

Question 20

Deformation of a ___ stretches the membrane and increases opening of a stretch-sensitive ion channel

Answer 20

Pacinian corpuscle

Question 21

define modality

Answer 21

Characteristics given to a stimuli

Question 22

What are the modalities?

Answer 22

vision
taste
audition
cold
cool
light touch
vibration
itch

Question 23

Is laughter a modlity?

Answer 23

No b/c there’s no direct stimulus

Question 24

Is sharp pain myelinated or unmyelinated? Is dull/aching pain myelinated or unmyelinated?

Answer 24

Myelinated

Unmyelinated

Question 25

Is a larger axon faster or slower?

Answer 25

Faster

Question 26

Define receptive field

Answer 26

Area of body that receives information b/c of AP

Question 27

Does a larger or smaller receptive field have more innervation/more sensation?

Answer 27

Smaller

Question 28

Why is it important that dermatomes overlap?

Answer 28

If nerves damaged, you won’t loose ability to receive information b/c of overlap

Question 29

What’s 2 point discrimination? Is it easier to distinguish separate points in large or small receptive fields? Why’s it important in clinical use?

Answer 29

Minimum distance required to perceive 2 simultaneously applied stimuli as distinct

Small b/c no overlap

Used to assess extend of nerve damage or peripheral nerve recovery after damage

Question 30

___ is defined as afferents that differ in the way they respond to stimulus over time

Answer 30

Temporal dynamics

Question 31

Describe slow and rapidly adapting afferents

Answer 31

Slow
- tells you about beginning and end
- gives information about size and shape of object

Rapidly
- give you information about movement
- Not continuous

Question 32

What are the 4 types of mechanoreceptors? Which ones are rapidly adapting/slow adapting? Do they all have a low/high threshold of action?

Answer 32

Meissner (rapidly)
Merkel cell (slow)
Ruffini (slow)
Pacinian (rapidly)

Low

Question 33

Meissner afferents provide information about? Where are they located? Small or large receptive field?

Answer 33

skin motion

Dermis

Small

Question 34

Merkel cell afferents provide information about? Where are they located? Small or large receptive field?

Answer 34

Edges, points, corners and curvature

Epidermis

Slow

Question 35

Pacinian afferents provide information about? Where are they located? Small or large receptive field?

Answer 35

Vibration and pressure

Dermis and subcutaneous layer

Large

Question 36

Ruffini afferents provide information about? Where are they located? Small or large receptive field?

Answer 36

Skin stretch

Dermis

Large

Question 37

Free nerve endings have a high/low threshold of action? What do they provide information about?

Answer 37

High

Temperature

Question 38

What are the 6 fibers we need to know? What are each of their types?

Answer 38

Aalpha (Ia)
Aalpha (Ib)
Abeta (II)
Adelta (III)
B
C (IV)

Question 39

Myelination state of A, B, and C fiber. Conduction speed of them? Large or small?

Answer 39

A and B are myelinated

A is fast and large
B is 2nd fastest and larger the C
C is slow and small

Question 40

Temperature is ___ adapting. Is there a larger range for cold or warm fibers? Why?

Answer 40

Slow adapting

Cold b/c it is not as painful as heat

Question 41

describe lateral inhibition. How does it work?

Answer 41

body finds where main point of stimulus came from

Collaterals inhibit the other neurons, which allows your body to determine where the stimulus came from

Question 42

Define labeled line theory

Answer 42

each nerve fiber is devoted to a modality has a distinct path leading to a specific area of the brain devoted to that modality

Question 43

What are the 3 ways your brain interprets stimuli in neural coding?

Answer 43

• Labelled line
• Stimulus intensity
• Recruitment (how many fibers are activated by stimulus)