W19/L7: Periph. Somatosensation

Question 1

What type of skin are the palms & soles of feet covered in?

Answer 1

Glabrous skin

Question 2

What are the two distinguishing features of glabrous skin?

Answer 2

No hair

Skin ridges

Question 3

Name 2 purposes of skin ridges

Answer 3

Provides grip

Tells us if the surface is moving

Question 4

What are the 4 types of mechanoreceptors in glabrous skin?

Answer 4

Meissner corpuscles
Merkel complexes
Ruffini organs
Pacinian corpuscles

Question 5

Which mechanoreceptors are found close to the surface?

Answer 5

Meissner corpuscles

Merkel complexes

Question 6

Which mechanoreceptors are found deeper in the skin?

Answer 6

Ruffini organs

Pacinian corpuscles

Question 7

Where are the cell bodies of the mechanoreceptors found?

Answer 7

In the dorsal root ganglie

Question 8

Where are Meissner corpuscles usually found?

which part of the skin layers

Answer 8

At the crest of the dermal ridges

Question 9

Where are Merkel complexes usually found?

which part of the skin layers

Answer 9

At the valleys of the neural ridges

Question 10

In which layer of skin are the Ruffini corpuscles normally found?

Answer 10

The dermis

Question 11

In which layer of skin are the Pacinian corpuscles normally found?

Answer 11

In the dermis & subcutaneous

Question 12

In what ways can we measure the sensitivity of the mechanoreceptors?

Answer 12

Minimum distortion that can be detected

Minimum weight that can be detected

Minimum frequency that can be detected as separate events

Question 13

How does activation of a Pacinian corpuscle lead to transduction of a nerve signal?

Answer 13

Stretch of the connective tissue pulls on the membrane of the nerve ending, which opens the Na+ channels

(simplified)

Question 14

What signal does a sub-threshold stimulus produce in the nerve cell?

Answer 14

None

Question 15

What sort of signals does a rapidly adapting mechanoreceptor send?

Question 16

What sort of signals does a slowly adapting mechanoreceptor send?

Question 17

Which of the glabours skin mechanoreceptors are slowly adapting?

Answer 17

Merkel complexes

Ruffini organs

Question 18

Which of the glabrous skin mechanoreceptors are rapidly adapting?

Answer 18

Meissner copuscles

Pacinian corpuscles

Question 19

What do Merkel complexes respond to?

Answer 19

Indentation

Question 20

What do Ruffini organs respond to?

Answer 20

Skin movement (sustained response)

Question 21

What do Meissner corpuscles respond to?

Answer 21

Skin movement (transient response)

Question 22

What do Pacinian corpuscles respond to?

Answer 22

Vibration

Question 23

How does the firing rate/threshold differ between tactile receptors and nociceptors?

Answer 23

The threshold of tactile receptors is easily reached, but the firing rate won’t increase when pain/damage increases

Nociceptors require a higher threshold, but can increase their firing rate to indicate severity of pain or damage.

Question 24

What’s the weird place (other than the skin) that we find Pacinian corpuscles?

Answer 24

In the peritoneal cavity

Question 25

How can Ruffini organs tell us about the position of our hands?

Answer 25

They detect skin stretching - which can also indicate finger potision

Question 26

What is the receptor field?

Answer 26

The territory that a single receptor is "responsible for"

Question 27

What arrangement of receptor fields would give us the most specific information about the location of a stimuli?

Answer 27

Small but densely packed

Question 28

What is the problem with dermatome pictures in textbook?

Answer 28

Dermatomes have significant overlap & can't be distinguished like that.

Question 29

Mechanoreceptor signals travel on which side of the spinal cord?

Answer 29

Ipsilateral

Question 30

Nociceptor signals travel on which side of the spinal cord?

Answer 30

Contralateral

Question 31

Where are the cell bodies of nociceptory nerves found?

Answer 31

Dorsal root gangleon