Lecture 11 - Body Senses and Perceptual Plasticity

Question 1

What are the 3 main somatosenses?

Answer 1

1. Cutaneous sense
2. Organic (internal) sense
   3.. Vestibular sense

Question 2

Explain what’s meant by the cutaneous sense

Answer 2

Sensitivity to stimuli that involve the
skin. e.g. pressure, vibration,
heating/cooling, and events that cause
tissue damage (i.e. pain).
Multiple receptor types are responsible for detecting specific sensations

Question 3

Explain what’s meant by the organic (internal) sense

Answer 3

• A sense modality that arises from
  receptors located within the inner
  organs of the body and muscles
• Proprioception: ability to sense position
  of the body and limbs

Question 4

Explain whats meant by the vestibular sense

Answer 4

• Perception of the body’s position,
  movement and balance.

Question 5

What is the vestibular system?

Answer 5

The vestibular system is part of the inner ear
* It is made up of three semicircular canals and the vestibular sacs

Question 6

What are the vestibular sacs?

Answer 6

two fluid-filled sacs in inner ear that sense movement of the head forward and backward or from side
to side (horizontally), sensing acceleration, or tilting up and down (vertically), sensing gravity

Question 7

What are the main layers of the skin?

Answer 7

Epidermis
Dermis
Hypodermis

Question 8

What is the epidermis?

Answer 8

The thin outer later that provides a protective barrier against pathogens

Question 9

What is the dermis?

Answer 9

Thickest layer containing
connective tissue,
capillaries, hair follicles and
sensory receptors

Question 10

What is the hypodermis?

Answer 10

Bottom layer of subcutaneous
tissue/fat

Question 11

What are free nerve endings?

Answer 11

Found in both hairy and non-hairy
skin (e.g., palms and soles of feet)
* Located close to the epidermis and
in hairy skin surround hair follicles.
Also distributed around bones,
within muscles and internal organs

Question 12

What are Merkel receptors in the skin?

Answer 12

Fires continuously in response to pressure
* Responsible for sensing fine details, shape
and texture

Question 13

What are Meissner Corpuscle receptors in the skin?

Answer 13

Fires only when a stimulus is first applied
and removed
* Responsible for controlling hand grip and
sensing motion across the skin

Question 14

What are Ruffini Cylinder receptors in the skin?

Answer 14

Fires continuously in
response to stimulation
* Associated with perceiving
stretching of the skin

Question 15

What are the Pacinian Corpuscle receptors in the skin?

Answer 15

Fires only when a stimulus is
first applied and removed
* Associated with sensing
rapid vibrations and fine
texture

Question 16

Table of sensory receptors in the skin

Answer 16

Question 17

What is proprioception?

Answer 17

our sense of body position and movement

Question 18

What is the function of the Spinothalamic Tract?

Answer 18

carries sensations of pain and temperature from spinal cord to thalamus

Question 19

What is the dorsal column (medial lemniscal) pathway?

Answer 19

carries sensations of touch and proprioception from spinal cord to thalamus

Question 20

Explain the case of Ian waterman

Answer 20

Contracted a viral illness when he was 19
* Damaged the dorsal column (medial
lemniscal) pathway in his spinal cord
* As a result, he could no longer sense
touch, pressure or proprioception
* Was unable to move and had to relearn to
walk and live independently

Question 21

What is tactile acuity?

Answer 21

The extent to which we can
distinguish between two points
of tactile stimulation across the body. Greatest in the fingertips due to high density of Merkel receptors

Question 22

What are the 4 cutaneous mechonareceptors?

Answer 22

Merkel Receptors
Meissner Corpuscle
Pacinian Corpuslce
Ruffini Cylinder