7 - Peripheral Sensory Mechanisms

Question 1

Four types of skin mechanoreceptors

Answer 1

Meissner corpuscles and Merkel complexes are close to the surface. Ruffini organs and Pacinian corpuscles are deeper in the skin.

Question 2

Glabrous skin

Answer 2

Skin on palms of hands, soles of feet (hairless)

Question 3

What innervate skin mechanoreceptors

Answer 3

Large myelinated axons with cell bodies in the dorsal root ganglia

Question 4

Role of free nerve endings in skin

Answer 4

Nociception, thermoception

Question 5

*Mechanoreceptors in the skin

Answer 5

Question 6

Receptive field (w/r/t skin mechanoreceptors)

Answer 6

Area of space over which a receptor can detect touch

Question 7

Basic way in which mechanoreceptors detect touch

Answer 7

Touch stretches receptor, opens Na+ channels in cell membrane. If this receptor potential is large enough, depolarisation.

Question 8

Broad difference in response to stimulus between different skin mechanoreceptors

Answer 8

Rapidly- and slowly-adapting to stimulus

Question 9

Slowly-adapting mechanoreceptors

Answer 9

Merkel, Ruffini

Question 10

Rapidly-adapting mechanoreceptors

Answer 10

Meissner, Pacinian

Question 11

Mechanoreceptors found at tips of epidermal ridges

Answer 11

Merkel complexes

Question 12

Mechanoreceptors found in upper dermis

Answer 12

Ruffini endings

Question 13

Mechanoreceptors found near surface of skin

Answer 13

Meissner receptors

Question 14

Mechanoreceptors in the deep dermis and hypodermis

Answer 14

Pacinian corpuscles

Question 15

Size of Pacinian receptor fields

Answer 15

Large

Question 16

Size of Meissner receptor fields

Answer 16

Small

Question 17

What do Merkel complexes respond to?

Answer 17

Indentation

Question 18

What do Meissner receptors respond to?

Answer 18

Transient response to skin movement

Question 19

What do Ruffini endings respond to?

Answer 19

Sustained response to skin movement

Question 20

What do Pacinian corpuscles respond to?

Answer 20

Transient response to vibration

Question 21

Low density (large receptor field) mechanoreceptors

Answer 21

Ruffini and Pacinian receptors (deep receptors)

Question 22

Most common skin mechanoreceptors

Answer 22

Meissner

Question 23

*Comparison chart of skin mechanoreceptors

Answer 23

Question 24

In picking up an object, what role do the four mechanoreceptors serve?

Answer 24

Meissner - Encode rate of force Merkel - Encode grip force Pacinian - Encode vibration (when you touch object) Ruffini - Encode hand posture

Question 25

Examples of mechanoreceptors not in the skin

Answer 25

Muscle spindle, Golgi tendon organs, cells in basilar membrane in ear

Question 26

Type of mechanoreceptor present in hairy skin that is absent in glabrous

Answer 26

Hair follicle

Question 27

Dermatome of the face

Answer 27

Trigeminal nerve (emerges from the pons)

Question 28

Dermatome

Answer 28

An area of skin supplied by a single spinal nerve. Overlap significantly.

Question 29

Dermatome with only a sensory branch

Answer 29

C1

Question 30

Fastest-conducting nerve fibre

Answer 30

Proprioceptive from muscle spindle

Question 31

Speed of nerve axons innervating skin mechanoreceptors

Answer 31

Second-fastest conducting axon

Question 32

Path of sensory afferent from mechanoreceptor

Answer 32

Cell body is in dorsal root ganglion. Enters dorsal horn of spinal cord, ascends to brainstem through dorsal column (white matter tract) ipsilaterally.