Ch. 6: Somatosensory System Flashcards Preview

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Flashcards in Ch. 6: Somatosensory System Deck (59):
1

What is Exteroception?

Discrimitive touch

Outside sensation

2

What is Proprioception?

Ability to know where you are in space

(Gives Cerebellum something to compare plan to)

3

What is Sensation?

Raw modality

(touch or pin prick)

4

What is Perception?

Making meaning of sensation

5

What so Sensory Receptors respond to?

A variety of stimuli

6

What are "modality-specific" receptors?

Have a modality gated channel at the end

7

What are the 3 types of "Modality Receptors?"

  1. Mechanoreceptors
  2. Chemoreceptors
  3. Thermoreceptors

8

What do Mechanoreceptors sense?

  • Touch
  • Pressure
  • Vibration
  • Stretch

9

What do Chemoreceptors sense?

Chemical in extracellular fluid cause AP to start

10

What do Thermoreceptors sense?

Hot and cold temperatures

11

What are Nociceptors?

  • Sense Pain!
    • High threshold
    • Need STRONG stimulus to activate
  • Subset of: Mechano-, Chemo- and Thermoreceptors

12

What does a Phasic Receptor sense?

  • Detect Change
    • start and stop of movement or touch
  • "Fast" adapting

13

What does a Tonic Receptor sense?

  • Sustained contact
    • detecting continuous duration of touch
  • "Slow adapting"

14

Somatosensory Peripheral Neurons are our named neurons.

What is their morphology?

  • Pseudounipolar
    • Peripheral axon projection
    • Central axon projection

15

What do Ia, Ib, II somatosensory neurons do?

  • Proprioception
    • Muscle spindle and muscle tendon
    • Muscle length

16

What does an A-beta somatosensory neuron do?

  • Exteroception
    • "touch" of skin and subcutaneous tissue
    • Discriminative touch - "I can describe and locate it"

17

What does an A-delta somatosensory neuron do?

  • "Fast," local pain & temp (superficial and deep)
    • sense mechanical touch → cant describe, just scream!

18

What does a C somatosensory neuron do?

  • "Slow." non-localized pain & temp (superficial and deep)
    • smaller = slower
    • say "dang that hurts"

 

  • Ex: stub toe, lightining bolt pain = A-delta, then it aches = C

19

What is a Receptive Field in cutaneous innervation?

Area of skin innervated by peripheral branch or sensory neurons

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20

In cutaneous innervation, what parts of the body have the highest Density of receptors?

  • Fingers, face, toes
  • More dense = more iscriminative touch

21

What receptors make up Fine Touch?

What do they do?

  • Combo of specialized receptor + A-beta afferent {biggest touch axon}
  • Discriminative touch - describe & locate pain

22

What are the 2 different types of fine touch receptors?

What do they do?

  1. Cutaneous (smaller receptive fields) - SUPERFICIAL
    • light touch, vibration, pressure, hair movement
  2. Subcutaneous (larger receptive fields) - DEEP
    • touch, vibration, stretch of skin

23

What named receptors make up Coarse Touch?

What do they do?

  • Free nerve endings + A-delta & C affernt
    • mediated by free nerve endings
    • A-delta: fast pain
    • C: slow pain

24

What named receptors sense Temperature?

 

  • free nerve ending + A-delta & C afferent

25

What named receptors sense Pain?

  • free nerve ending + A-delta & C afferent

26

What is the spinal nerve made up of?

  • Where ventral and dorsal roots come together
    • all sensory, motor and autonomic

27

What happens when there is damage to a spinal nerve?

damage causes sensory loss in a dermatomal pattern

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28

What axons feed a peripheral nerve?

Axons from more than one spinal level

(mixing occurs in plexus)

29

What happens when a peripheral nerve is damaged?

Sensory loss presents as a subsection of one or many dermatomes BUT, not a whole dermatome 

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30

In the muscle spindles, what do the Nuclear Bag Fibers sense?

Change and rate of change of muscle length

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31

In the muscle spindles, what do the Nuclear Chain Fibers sense?

change of muscle length

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32

In the muscle spindles, what do the Group Ia sensory axons innervate?

  • Wrap center of bag and chain fibers
    • "Primary endings"
    • All info about length, change of length and rate of change of length 

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33

In the muscle spindles, what do Group II sensory axons innervate?

  • End of chain fibers
    • ONLY give info about length

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34

Where are Intrafusal Muscle Fibers located?

What do they do?

  • Inside the spindle at the ends of each bag and chain fiber

 

  • Keep muscle fiber sensative to length

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35

Where are Extrafusal Muscle Fibers located?

What do they do?

  • Outside of spindle! (outside of the picture and not shown)
  • Move muscle, contract

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36

What motor neurons innervate Intrafusal Muscle Fibers?

What is their purpose?

  • A-Gamma Motor Neurons
    • Keep spindle sensative to new changes in length

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37

What are Golgi Tendon Organs (GTO's)?

What do they do?

  • Specialized mechanoreceptors in the tendons of the muscles
    • Senses tension
    • More tension = More AP's

38

What Sensroy Axon innervates the Golgi Tendon Organs (GTO's)?

Group Ib

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39

In the joint, what do Capsule Receptors do?

Where are they located?

  • Detect Joint Movement
    • mechanoreceptors - detect passive movement and extreme ranges

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40

In the joint, what do Ligament Receptors do?

Where are they located?

  • Sense tension in ligaments
    • Located in ligaments

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41

In the joint, what do Free Nerve Endings do?

Where are they located?

  • Sense pain and inflammation
    • Inside joint line and back on knee

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42

What contributes to our sense of proprioception?

Deep

  • Muscle Spindles - length, change of length
  • Tendon Receptors - tension on muscle/MSK info
  • Joint Receptors - position & stress on joints

Superficial

  • Cutaneous Mechanoreceptors - weightbearing

43

Conscious Relay carries what sensory info?

Where does the info end up?

  • Light touch
  • Concious proprioception
  • "Fast" pain

Ends in cerebral cortex → can characterize and localize

44

Divergent Pathways carry what sensory info?

Where does the info end up?

  • "Slow" Pain
  • Emotional and Autonomic responses to pain

End subcortical

45

Unconscious Relay carries what sensory info?

Where does the info end up?

  • Unconsciouse proprioception
  • Deep singals from muscles, tendons and joints

End in Cerebellum

46

What are Projection Neurons?

  • MAIN neurons of pathway
    • Labeled where they are in the chain (1st order, 2nd order, 3rd order)

47

Where are 1st Order Projection Neurons located?

  • First in line
  • Peripheral
    • Psuedo-unipolar

48

Where are 2nd and 3rd Order Projection Neurons located?

  • 2nd and 3rd in line
  • Central

49

What are Interneurons?

  • Tiny, not part of relay
    • Introduce synapses → can turn up/down, gather/disperse

50

What are High Fidelity Pathways?

  • Discriminative
  • High degree of somatotopic organization (body map)

**End in Cortex or Cerebellum**

51

What are Low Fidelity Pathways?

  • Non-driminative
  • Low degree of somatotopic organization (body map)

**End in Subcortical - autonomic & emotional areas**

52

What are the 3 types of pathways to the brain?

  1. Conscious Relay
  2. Divergent Pathways
  3. Unconscious Relay

53

What is processed in the Primary Cortex?

Where is it located?

  • Where sensation comes to consciousness
  • Post central gyrus of the parietal lobe

54

What is processed in the Association Cortex?

Where is it located?

  • Makinging meaning of sensation
  • Other parts of Parietal lobe

55

When someone punches you, what pathway tells you WHERE they hit you?

What type of relay is this?

Spinothalamic

Conscious Relay

(Anterolateral columns, A-delta → fast pain and fast temp)

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56

When someone punches you, what pathway TURNS your head to the source of pain?

What type of relay is this?

Spinomesencephalic (superior colliculus)

Divergent Pathway

(Anterolateral Columns, C → slow pain)

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57

When someone punches you, what pathway increases AROUSAL in response to pain?

What type of relay is this?

Spinoreticular

Divergent Pathway

(Anterolateral Columns, C → slow pain)

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58

When someone punches you, what pathway activates the SUBCORTICAL autonomic and emotional responses to pain?

What type of relay is this?

Spinolimbic

Divergent Pathway

(Anterolateral Columns, C → slow pain)

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59

What pathway sends proprioceptive info to cerebellum for movement correction?

What type of pathway is this?

Spinocerebellar

(Unconcious Pathway, Ia, Ib, II → proprioception)

High Fidelity