Chapter 12: The Somatic Sensory System

Question 1

somatosensory system

Answer 1

sensory network that monitors the surface of the body and its movements, responds to many different kinds of stimuli: the sense of touch, temperature, pain, and body position

Question 2

somatosensation

Answer 2

our temperature receptors also respond to certain chemical stimuli

Question 3

capsaicin

Answer 3

chemical found in hot peppers, stimulates the receptors for painful heat.

Question 4

Szechuan peppers

Answer 4

stimulate the heat receptors, and in addition stimulate certain touch receptors that give a tingling sensation.

Question 5

menthol and mint

Answer 5

stimulates coolness receptors

Question 6

tickle

Answer 6

the sensation of tickle is interesting and poorly understood, you can’t tickle yourself because your brain compares the resulting stimulation to the “expected” stimulation and generates a weaker somatosensory response than you would experience from unexpected touch.

Question 7

types of layers of skin

Answer 7

hair and glabrous, and epidermis (outer), and dermis (inner)

Question 8

functions of skin

Answer 8

protects, prevents evaporation of body fluids, and provides direct contact with world.

Question 9

pacinian corpuscles

Answer 9

receptor that responds to a sudden displacement of the skin or high-frequency vibrations on the skin. The onion-like outer structure provides a mechanical support to the neuron inside it so that a sudden stimulus can bend it, but a sustained stimulus cannot.

Question 10

Ruffini’s endings

Answer 10

stretching of your skin

Question 11

Meissner’s corpuscles

Answer 11

movement across the skin

Question 12

Merkel’s disks

Answer 12

respond to light touch, suppose you feel objects with thin grooves without looking at them, and try and feel whether the grooves go left or right or up and down.

Question 13

Krause end bulbs

Answer 13

uncertain

Question 14

two-point discrimination

Answer 14

a simple measure of spatial resolution

Question 15

primary afferent axons

Answer 15

axons bringing information from the somatic sensory receptors to the spinal cord or brain stem, in the somatic sensory system. Enter the spinal cord through the dorsal roots, their cell bodies lie in the dorsal root ganglia. Widely varying diameters.

Question 16

Diameter of primary afferent axons

Answer 16

widely varying diameters, and their size correlates with the type of a sensory receptor to which they are attached.

Question 17

spinal segments

Answer 17

30 spinal segments are divided into four groups, Cervical, Thoracic, lumbar, and sacral.

Question 18

human central nervous system

Answer 18

information from touch receptors in the head enter the CNS through cranial nerves, information from receptors below the head enter the spinal cord and pass toward the brain through the 30 spinal nerves and 1 coccygeal nerve. Each spinal nerve has a sensory component and a motor component and connects to a limited area of the body.

Question 19

pain path

Answer 19

the pain path has sets of axons conveying sharp pain, slow burning pain, and painfully cold sensations

Question 20

nervous system

Answer 20

the nervous system codes the differences among these sensations in terms of which cells are active.

Question 21

Dermatome

Answer 21

each spinal nerve innervates a limited area of the body

Question 22

emotional pain

Answer 22

a separate pathway to the hypothalamus, amygdala, and cingulate cortex produces the emotional aspect.

Question 23

damage to the cingulate gyrus

Answer 23

people still feel pain, but it no longer distresses them.