Exam 2 Somatic sensory

Question 1

What is sensitive to many kinds of stimuli? -including pressure, position of joints and muscles, temperature of the limbs and pain

Answer 1

Somatosensory system

Question 2

How is the somatosensory system is different from other sensory systems?

Answer 2

• Its receptors are distributed throughout the body rather than being concentrated at small, specialized locations.
• Receptors are found in the skin, body wall, muscles, tendons, ligaments, connective tissue of the joints, and internal organs.
• The somatosensory system is a group of at least 4 senses rather than one:

–These include touch, temperature, body position, pain and various subdivisions of these senses.

Question 3

What are some examples of modality vs sub modality and sub sub modality

Answer 3

Question 4

In afferent axons how does size affect speed?

Answer 4

Smaller the diameter the slower the speed

Question 5

What are the two pathways of Somatic Sensation?

Answer 5

Dorsal column-medial lemniscal pathway

Spinothalmaic pathway

Question 6

What is the dorsal column medial lemniscal pathwya responsible for?

and what dorsal root axons does it use?

Answer 6

Touch, vibration, two-point discrimination, proprioception

Aa(alpha)

Ab(beta)

Ad

Question 7

What is the spinothalamic pathway responsible for?

What dorsal root axons does it use?

Answer 7

Pain, temperature, and some touch

• Ad
• C

Question 8

What are most of the sensory receptors in the skin?

-These receptors are sensitive to physical distortion such as bending or stretching

Answer 8

Mechanoreceptors

Question 9

What are these examples of?

–Hair receptor

–Pacinian corpuscle

–Ruffini ending

–Meissner corpuscle.

–Merkel disk receptor, the only sensory receptor cell type in the somatosensory system

Answer 9

Mechanoreceptors

Question 10

What sensory field is bigger? Those of Pacinian corpuscles or Meissners

Answer 10

Pacinian

Question 11

This type of adapting mechanoreceptors respond quickly at first then stop firing even though the stimulus continues.

–Best suited to represent time varying (e.g., vibrating or moving) stimuli.

Answer 11

Rapidly

Question 12

This type of adapting mechanoreceptors generate a more sustained response during a long stimulus.

–Best suited to represent static stimuli

Answer 12

Slowly adapting

Question 13

Is the pacinian corpuscles rapid or slow adapting?

Answer 13

Rapid

•The capsule makes the Pacinian corpuscle exquisitely sensitive to vibrating, high-frequency stimuli, and almost unresponsive to steady pressure.

-Acting as a filter to modify the stimulus, if there is no capsule there is not much change

Question 14

What are some characteristics of mechanoreceptors?

Answer 14

Question 15

• Which thermoreceptor begins firing above 30oC and stop firing above 45oC.
• Which thermoreceptor fires faster over a broad range of skin temperatures from about 30oC down to 10oC.

Answer 15

Warm

Cold

Question 16

Explain this image

Answer 16

• At the horizontal arrow, one cannot tell if the temperature is cold or warm because both cold and warm receptors are activated equally.
• At the vertical arrow, one may sense cold, even though the temperature is high because cold receptors are activated more than warm receptors.

Question 17

• Which thermoreceptors fire faster during reductions in temperature (blue arrow).
• Which thermoreceptors fire faster during increases in temperature (red arrow).

Answer 17

Cold

Warm

Question 18

What is the purpose of pain?

Answer 18

–Protective mechanism for the body

• Occurs in response to tissue damage
• Causes individual to react to remove stimulus.

Question 19

What are the four categories of nociceptors based on function (free, branching, unmyelinated nerve endings that signal that body tissue is being damaged or is at risk of being damaged).

Answer 19

Mechanionociceptors

Thermal nociceptors

Chemically sensitive, mechanically sensitive nociceptors

Polymodal

Question 20

Which pain receptor responds to intense mechanical stimulation (pinching, cutting, stretching)

Answer 20

Mechanociceptors

Question 21

Which nociceptors respond to burning heat (>45oC, tissue proteins become denatured and damage occurs) or extreme cold.

Answer 21

Thermal

Question 22

Which nociceptors respond to a variety of agents from the environment or from the tissue itself.

•Examples include potassium, extremes of pH, neuroactive substances such as histamine and bradykinin and various irritants.

Answer 22

Chemically sensitive, mechanically insensitive

Question 23

What nociceptors respond to high intensity stimuli that are combinations of mechanical, thermal and chemical stimuli.

•They are present in most body tissues except the brain.

Answer 23

Polymodal

Question 24

What are some characteristics of slow and fast pain?

Answer 24

Question 25

Which type of pain is transmitted by relatively thicker (and therefore faster conducting) nerve fibers (Adelta fibers)

and

Which type of pain is transmitted by very thin nerve fibers (C fibers)

Answer 25

Fast pain

Slow Pain

Question 26

What type of pain is

labor pain,

pain starting after fast pain from an injury

Chemical burn

Answer 26

Slow Pain

Question 27

What type of pain is pain from a surgical incision

Answer 27

Fast pain

Question 28

–Pain referred from area of damage to another area.

•Example: kidney pain might feel like lower back pain

Answer 28

Referred Pain

Question 29

–Pain of a missing limb.

Answer 29

Phantom Pain

Question 30

What type of pain comes from

–Alcohol

•Toxicity of alcohol itself irritates the meninges.

–Constipation

•From absorbed toxic products or changes in circulatory system resulting from loss of fluid in the gut.

Answer 30

Intracranial headache

Question 31

What type of pain comes from:

–Muscle spasm

• Emotion/tension causes muscles of the head to become spastic.
• Pain is referred to overlying areas of the head.

–Sinus headache

• Pain from mucous membranes of nose and nasal sinuses
• Pain is referred behind the eyes or forehead or face.

–Eye disorders

• Difficulty focusing stresses ciliary muscles and can cause spasms in facial and extraocular muscles.
• Excessive irradiation by light rays (especially UV) causes irritation of the membranes around the eye.

Answer 31

Extracranial headache

Question 32

What is the Gate theory of pain?

Answer 32

–Pain can be modified by nonpainful sensory input and by neural activity from various nuclei within the brain.

• Pain evoked by activity in nociceptors (Adelta and C fibers) can be reduced by simultaneous activity in low-threshold mechanoreceptors (Aalpha and Abeta fibers).
• This explains why it feels good to rub the skin around your shin when you bruise it.