Lecture 6: General Sensory Mechanisms III

Question 1

Two-point discrimination touch

Answer 1

Ability to distinguish 2 separate points as close to 2 mm apart

Question 2

Lateral inhibition

Answer 2

Blocks lateral spread of excitatory signals, increasing degree of contrast in cerebral cortex

Question 3

Fast pain

Answer 3

Felt within 0.1 s after stimulus, not felt in deeper tissue, elicited by mechanical/thermal stimuli; carried by A fibers terminating in lamina I

Question 4

Slow pain

Answer 4

Begins 1 s after stimulus is applied and gradually increases, described as aching/throbbing, elicited by mechanical/thermal/chemical stimuli; carried by C fibers which terminate in layers II and III

Question 5

Which pain fibers make up the neospinothalamic tracts?

Answer 5

Fast pain

Question 6

Which pain fibers make up the paleospinothalamic pathway?

Answer 6

Slow pain

Question 7

Which neurotransmitter is used by A fibers of fast pain path?

Answer 7

Glutamate

Question 8

What do the slow pain C fibers release during their pathway?

Answer 8

Glutamate and substance P

Question 9

Brown-Sequard Syndrome

Answer 9

Occurs when there is a hemisection of spinal cord; all motor, kinesthetic function, 2-point touch lost on side of transection and below, spinothalamic sensations lost on opposite side of body and in dermatomes 2-6 segments below

Question 10

What are the 3 components of the Analgesia system?

Answer 10

Periaquaductal gray and periventricular regions of brainstem and third ventricle, Raphe magnus nucleus and retircular nuclei in medulla, Pain inhibitory complex in dorsal horns

Question 11

What are the 3 types of receptors that discriminate thermal gradations?

Answer 11

Cold, Warmth, Pain

Question 12

Referred pain

Answer 12

Occurs when visceral pain fibers are stimulated and stimulate some of the pain fibers that conduct pain signals from the skin

Question 13

What kind of stimuli excites visceral pain nerve endings?

Answer 13

Ischemia of visceral tissue, chemical damage to surface, smooth muscle spasm, etc.

Question 14

Name 2 visceral areas that are insensitive to pain of any type

Answer 14

Parenchyma of liver, alveoli of lungs

Question 15

Headaches

Answer 15

Result of pain referred to surface of head from deep head structures; may result from meningitis, low CSF pressure, alcohol, muscle spasm, etc.

Question 16

Where do secondary fibers of the paleospinothalamic pathway terminate?

A. VPL of thalamus
B. Ventrobasal nuclei of thalamus
C. Throughout the brainstem
D. Somatosensory cortex

Answer 16

C. throughout the brainstem

Question 17

Which of the following is not a result of Brown-Sequard syndrome?

A. All motor functions blocked on the side of the transection below level of transection
B. All vibration and two-point touch lost on the side of transection below level of transection
C. All sensations of pain, heat, cold are lost on the side of transection 2-6 dermatomes below transection
D. All sensations of pain, heat cold are lost on the opposite side of transection 2-6 dermatomes below transection

Answer 17

C. All sensations of pain, heat cold are lost on the side of transection 2-6 dermatomes below transection

Question 18

Which of the following is not a component of the analgesia system?

A. Pain inhibitory complex
B. Olivary nuclei
C. Periaquaductal grey
D. Raphe magnus nucleus

Answer 18

B. Olivary nuclei

Question 19

What type of fibers transmit visceral pain from thoracic and abdominal cavities?

A. A fibers
B.Group IIA fibers
C. C fibers
D. Group IIIB fibers

Answer 19

C. C fibers