Exteroception

Question 1

Larger diameters of nerves are

Answer 1

Faster, usually myelinated

Question 2

Small diameter are

Answer 2

Slow, 1 m/s

Question 3

Aα
Ia Ib

types of axons.

Answer 3

PROPRIOCEPTION
Muscle spindle afferent (a)
Tendon organ afferent (b)

Diameter (µm) 10-20

Speed (m/sec) 60-120

Question 4

Aβ

types of axons.

Answer 4

Mechanoreceptors of skin, secondary muscle spindle afferents

Diameter (µm) 5-10

Speed (m/sec) 30-60

Question 5

Aδ

types of axons.

Answer 5

Sharp pain, cold temperature

Diameter (µm) 1-5

Speed (m/sec) 4-30

Question 6

C

types of axons.

Answer 6

Warm temperature, burning pain, itch, crude touch

Diameter (µm) 0.2-1.5

Speed (m/sec) 0.5-2

Question 7

Meissner’s corpuscles

mechanoreceptors

Answer 7

Membrane bound. Touch changes membrane shape–> Action potential

Shallow in skin

Small field

Fast= vibration sense

Question 8

Merkel’s discs

mechanoreceptors

Answer 8

small fields and are slowly adapting- steady touch

Shallow in skin

Small field

Question 9

Pacinian corpuscles

mechanoreceptors

Answer 9

Membrane bound. Touch changes membrane shape–> Action potential

Steady touch leads to no AP, aka fast adaption
Feels vibration

Deep in skin

Large field

Question 10

Ruffini endings

mechanoreceptors

Answer 10

slowly-adapting subtypes= steady touch

steady touch= frequent AP

Deep in skin

Large field

Question 11

other lemniscal
receptor types, such as hair follicle receptors in hairy skin. The dermal tissue around each hair follicle is penetrated by several myelinated axons, and these produce several unmyelinated branches. Some branches run up and down the hair follicle, others spiral around it. Bending of the hair shaft activates the terminals, and they are rapidly-adapting.

Answer 11

x

Question 12

Mechanoreceptors from the skin (carrying information about touch, pressure, vibration
and hair bending) and joint receptors have large, myelinated axons ___________

Answer 12

(Aβ)

Question 13

support the fine tactile sense of the fingertips, and innervation density studies support this proposal.

Answer 13

Merkel’s discs

mechanoreceptors

Question 14

support the fine tactile sense of the fingertips, and innervation density studies support this proposal.

Shear, or slip between skin and object, or between skin and deeper tissues results in stretch of the endings.

Answer 14

Ruffini endings

mechanoreceptors

Question 15

Afferents with large receptive fields lie deep in the dermis and subcutaneous tissues

follow vibratory stimuli (at several 100 Hz) that move the skin by only 1 micron

Answer 15

Pacinian corpuscles

mechanoreceptors

Question 16

thought to correspond to the rapidly-adapting afferents with small receptive fields

Answer 16

Meissner’s corpuscles

mechanoreceptors

Question 17

Trigeminal system

Answer 17

Crosses immediate in mid-pond

Question 18

stimulation cells in different Brodmann’s areas

Answer 18

Brodmann’s areas communicate with each other (area 2 talks to 4) to integrate touch and movement

Question 19

receives input from the thalamus

Answer 19

Cortical Layer IV

These interconnections imply that cortical columns serve as computational modules that transform information received from the thalamus and redistribute it to other regions of the brain.

Question 20

projects back to the thalamus

Answer 20

Cortical layer VI

These interconnections imply that cortical columns serve as computational modules that transform information received from the thalamus and redistribute it to other regions of the brain.

Question 21

projects to other subcortical structures

Answer 21

Cortical layer V

These interconnections imply that cortical columns serve as computational modules that transform information received from the thalamus and redistribute it to other regions of the brain.

Question 22

project to other areas of somatosensory cortex

Answer 22

Cortical layers II and III

These interconnections imply that cortical columns serve as computational modules that transform information received from the thalamus and redistribute it to other regions of the brain.

Question 23

The different layers do ________

Layer IV receives input from the thalamus, layer VI projects back to the thalamus, layer V projects to other subcortical structures, while layers II and III project to other areas of somatosensory cortex.

Answer 23

project to and receive projections from different areas of the brain.