Mechanical Senses

Question 1

Vestibular Organ

Answer 1

Saccule, utricle, and three semicircular canals
Adjacent to cochlea
Monitors movement and directs compensatory movements of the eyes

Question 2

Otoliths

Answer 2

Calcium carbonate particles lying next to hair cells
When head tilts, otoliths push against sets of hair cells to excite them
Tell brain which direction you are moving and record direction head tilts when at rest
Found inside cross section of saccule and utricle

Question 3

Semicircular Canals

Answer 3

Filled with fluid and lined with hair cells
Oriented in perpendicular planes
Acceleration of head causes fluid to move
Fluid pushes against hair cells, setting off action potentials
Record only the amount of acceleration (not position at rest)
Insensitive to sustained motion (e.g. notice acceleration on bike but with continuous movement stop responding)

Question 4

Somatosensation

Answer 4

Sensation of the body and its movements

Question 5

Types of Somatosensation

Answer 5

Exteroception
Interoception
Proprioception

Question 6

Exteroception

Answer 6

Sensation info coming from skin

Question 7

Interoception

Answer 7

Sensation info coming from internal organs

Question 8

Proprioception

Answer 8

Sensation info coming from muscles and tendons

Question 9

Low Threshold Mechanoreceptors (LTMRs)

Answer 9

Code for stimuli that are gentle enough that they don’t hurt
Merkel disk
Pacinian corpuscle
Ruffini ending
Meissner corpuscle
Communicate quickly
Have different concentrations across skin

Question 10

Discrimination Threshold

Answer 10

Distance between two stimuli at which people are just able to tell they are being touched by two stimuli rather than one
Best in fingers and palms
Worst in shoulders and calves

Question 11

Bare/Free Nerve Ending

Answer 11

Little/no myelin - travel slow
Thicker axons use glutamate and neuropeptides
Thinner axons use glutamate

Question 12

Pain Pathway

Answer 12

Crosses spinal cord immediately (ascends contralaterally)
Extends to ventral posterior nucleus of thalamus, then to somatosensory cortex

Question 13

Three Types of Mechanical Transduction

Answer 13

Stretch activation
Activation by tethers
Indirect activation

Question 14

Stretch Activation

Answer 14

Channel is pulled open as membrane molecule stretches apart during touch

Question 15

Activation by Tethers

Answer 15

Protein tethers attached to ion channels and extracellular matrix or cytoskeleton inside cell (or both)
Touch creates mechanical movement and pulls on tether to open channel

Question 16

Indirect Activation

Answer 16

Tethers activate protein separate from ion channels which opens channels via messenger

Question 17

Ways to relieve pain

Answer 17

Opiods
Cannabinoids
Capsaicin
Placebos

Question 18

Two Types of Itch

Answer 18

Contact with certain plants (e.g. cowhage)
Mild tissue damage (e.g. healing cut)