Somatosensory System

Question 1

Division of Nervous System

Answer 1

Afferent (Sensory)

Efferent (Motor)

Question 2

Afferent Division of Nervous System

Answer 2

Sensory Division:
transmits nerve pulses from peripheral organs to CNS
responsible for detecting stimuli

Question 3

Efferent Division of Nervous System

Answer 3

Motor Division:

transmits nerve impulses from CN to peripheral organs

Question 4

What is the Somatosensory System?

Answer 4

responsible for sensations that arise from tissues, other than specialised sense organs (e.g. Eye, ear, nose)

Question 5

What organs are involved in somatosensory system?

Answer 5

skin, viscera, muscles, and joints

Question 6

What are the three major components of the Somatosensory System?

Answer 6

1. Cutaneous Sensation
2. Interoreception
3. Proprioception

Question 7

Cutaneous Sensation of Somatosensory System

Answer 7

arise from the skin

Question 8

Interoreception of Somatosensory System

Answer 8

arise from the viscera, muscles, and joints which are not related to movement

Question 9

Proprioception of Somatosensory System

Answer 9

arise from viscera, muscles, and joints which are related to movement

Question 10

structural components of the somatosensory system and where these are located in both the peripheral and central nervous system

Answer 10

• 3 neural pathway
• stimulus activates primary sensory neurone & releases APs which travel through pathway
• APs reach cerebral cortex
• stimulus is perceived

Question 11

Transduction

Answer 11

he mechanisms by which stimulation of the peripheral tissues produces an action potentials in the primary sensory neuron (receptor)

Question 12

Frequency Encoding:

Answer 12

The way in which the nervous system encodes the size of a peripheral stimulus.

Question 13

The size of a peripheral stimuli is encoded by the frequency of what?

Answer 13

Action Potentials

i.e. Low frequency of APs = smaller stimulus

Question 14

Receptive Field:

Answer 14

the skin area that produces action potentials in that particular neuron/ The area of the skin that when stimulated it produces action potentials.

Question 15

Innervation Density:

Answer 15

he extent to which a particular peripheral tissue is able to detect as stimulus is directly related to the number of neurons that innervate a particular unit area which is referred to as innervation density.
The higher the innervation density the more neurons terminate in each cm2 of that tissue.
E.g. Finger Tips: ~140 pressure receptors in each cm2
Back: <1 pressure receptors in each cm2

Question 16

Adaptation:

Answer 16

the way an individual primary sensory neuron responds to a sustained stimulus.

Question 17

Slowly Adapting:

Answer 17

action potentials begin when stimulus is applied, continue throughout the duration of the stimulus, and stop one stimulus is removed. Response doesn’t change throughout the duration of the stimulus.

Question 18

Rapidly Adapting:

Answer 18

same stimulus & duration but after a few seconds the neurons adapt and stop producing action potentials.

Question 19

three major classes of sensations from stimulation of the skin.

Answer 19

1. Low Intensity Mechanical Stimuli
2. Low Intensity Thermal Stimuli
3. High Intensity Stimuli

Question 20

Low Intensity Mechanical Stimuli:

Answer 20

non-painful
three sensations:
1. pressure
2. touch
3. vibration

Question 21

the three sensations of low intensity mechanical stimuli is referred to as what?

Answer 21

Mechanoreception

Question 22

Describe the sensation of pressure:

Answer 22

the degree of skin indentation

Question 23

Describe the sensation of touch:

Answer 23

the rate at which a skin indentation is applied

Question 24

Describe the sensation of vibration:

Answer 24

the frequency of a vibratory stimulus

Question 25

Low Intensity Thermal Stimuli:

Answer 25

do not produce damage to the skin and are non-painful
Two Types:
1. Cold receptors
2. Warm receptors

Question 26

Collectively Cold and Warm receptors are referred to as what?

Answer 26

thermoreception

Question 27

High Intensity Stimuli:

Answer 27

produces damage to the skin and the sensation of pain.
Two Types:
1. Sharp Pain
2. Burning Pain

Question 28

Describe Sharp Pain Sensation & an example:

Answer 28

occurs shortly after a mechanical injury i.e. Paper cut

Question 29

Describe Burning Pain Sensation & an example:

Answer 29

a few seconds after sharp pain we experience a burning sensation. We can also elicit burning pain from high temperatures or pain-producing chemicals (e.g. Acids).

Question 30

Sharp & Burning Pain Sensation is collectively referred to as what?

Answer 30

nociception

Question 31

Primary Sensory Neurone responsible for Mechanoreception

Answer 31

Low Threshold Mechanoreceptors