Peripheral Somatosensory Mechanism

Question 1

What is the primary function of skin ridges?

Answer 1

provide grip (they also have receptors embedded within)

Question 2

Mechanoreceptors tend to densely occupy what kind of skin?

Answer 2

glabrous skin

Question 3

What are the four types of mechanoreceptors? What kind of information do they provide to the brain?

Answer 3

Meissner corpuscles + Merkel complexes close to the surface Ruffini organs and Pacinian corpuscles deeper in the skin conscious sense of touch

Question 4

T/F Mechanoreceptors have the fastest conducting axons

Answer 4

false, muscle proprioceptors have faster conduction

Question 5

Where are meissner and merkel receptors found?

Answer 5

at the dermal ridges close to the surface

Question 6

Where can we find Ruffini corpuscle?

Answer 6

embedded in the connective tissue

Question 7

Where can we find Pacinian corpuscle

Answer 7

in the dermis, very close to subcutaneous layer

Question 8

Mechanorecpetors detect _________ and use receptors that have __________ nerve endings. They can detect up ________ and also _________ of force.

Answer 8

distortion of the skin encapsulated magnitude frequency

Question 9

How does physical distortion get transduced to neural signal

Answer 9

The proteins are tethered to each other, so physically force can pull open a series of Na channels to create action potential.

Question 10

What is the difference between slow and rapid adaptation

Answer 10

slowly adapting receptors encode the stimulus over a long time frame, whereas rapidly adapting receptors give the initial impulse upon activation

Question 11

What is the difference between receptors for tactile information and pain?

Answer 11

the range of response and the threshold of activation for somatosensation are smaller

Question 12

Which receptors are slowly adapting?

Answer 12

Merkel and Ruffini

Question 13

Which receptors are rapidly adapting?

Answer 13

Meissner and Pacinian

Question 14

In terms of receptor number, deeper receptors tend to be __________

Answer 14

less dense

Question 15

Which mechanoreceptor is most numerous

Answer 15

Meissner

Question 16

What do the four types of receptors primarily detect?

Answer 16

Meissner - transient response to skin movement Merkel - edge or indentation Ruffini - stretch and direction of stretch. Proprioceptive Pacinian - vibration

Question 17

When picking up an object, what do the four receptors encode individually

Answer 17

Meissner - rate of force (change in surface contact) Merkel - grip force Pacinian - vibration Riffini - hand posture

Question 18

What is a receptive field?

Answer 18

how much territory a single fibre respond to

Question 19

Receptive fields often ________ , and where the receptive fields are dense, there is higher __________ . On our upper limb, there are denser receptive fields on the ________, and less dense in other parts

Answer 19

overlap

spatial resolution

fingertip

Question 20

What is the difference between the signal transmission of nociceptor and mechanosensory receptor?

Answer 20

nociceptors make their first synapse in the spinal cord

Question 21

Why do deeper receptors have larger receptive fields?

Answer 21

Because force radiates over longer distance, and deeper receptors can respond to singals that are off target