7.2.1 The Mechanical Senses 2

Question 1

The thicker and faster axons convey ____ pain. The thinner ones convey duller pain, such as postsurgical pain.

Answer 1

sharp

Question 2

Although pain messages reach the brain more slowly than other sensations, the brain processes pain information ____. Motor responses to pain are faster than motor responses to touch stimuli.

Answer 2

rapidly

Question 3

Pain axons release two neurotransmitters in the spinal-cord. Mild pain releases the neurotransmitter glutamate, whereas stronger pain releases both glutamate and _____.

Answer 3

substance P

Question 4

The pain-sensitive cells in the spinal-cord relay information to several sites in the brain. One path extends to the ventral posterior nucleus of the ____ and from there to the somatosensory cortex, which responds to painful stimuli, memories of pain, and signals that warn of impending pain.

Answer 4

thalamus

Question 5

The pain pathway crosses immediately from receptors on the one side of the body to a tract ascending the ____ side of the spinal-cord.

Answer 5

contralateral

Question 6

Painful stimuli also activate the path that goes through the reticular formation of the medulla and then to several of the central nuclei of the thalamus, the amygdala, hippocampus, prefrontal cortex, and cingulate cortex. These areas react not to the sensation but to its ____ associations.

Answer 6

emotional

Question 7

A hypnotic suggestion to feel no pain decreases the responses in the cingulate cortex without much effect on the somatosensory cortex. That is, someone responding to a hypnotic sensation still feels the painful sensation but reacts with ____ ____.

Answer 7

emotional indifference

Question 8

Relieving pain. The brain puts the brakes on prolonged pain by ____ mechanisms – systems that respond to opiate drugs and similar chemicals.

Answer 8

opioid

Question 9

Opiates bind to receptors found mostly in the spinal-cord and the ____ ____ area of the midbrain.

Answer 9

preaqueductal grey

Question 10

Later researchers found that opiate receptors act by blocking the release of ____.

Answer 10

substance P

Question 11

The discovery of opiate receptors was exciting because it was the first evidence that opiates act on the ____ ____ rather than on the injured tissue.

Answer 11

nervous system

Question 12

Furthermore, it implied that the nervous system must have its own opiate-type chemicals. The transmitters that attach to the same receptors as morphine are known as endorphins – a contraction of ____ ____.

Answer 12

endogenous morphines

Question 13

The gate theory was an attempt to explain why some people ____ pain better than others and why the same injuries hurt worse at some times than others.

Answer 13

withstand

Question 14

According to the gate theory, spinal-cord neurons that receive messages from pain receptors also received input from touch receptors and from axons descending from the brain. These other inputs can close the “gates” for the ____ ____– and we now see that they do so at least partly by releasing endorphins.

Answer 14

pain messages

Question 15

Nonpain stimuli modify the ____ of pain. When you have an injury, you can decrease the pain by gently rubbing the skin around it or by concentrating on something else.

Answer 15

intensity

Question 16

People also experience pain relief from ____. A ____ is a drug or other procedure with no pharmacological effects.

Answer 16

placebos

Question 17

People who receive placebos do not just say the pain decreased; scans of the brain and spinal-cord also show a ____ response to pain.

Answer 17

decreased

Question 18

However, a placebos affects are mainly on the emotional response to pain, not the sensation itself. That is, a placebo decreases the response in the ____ ____ but not the somatosensory cortex.

Answer 18

cingulate cortex

Question 19

Placebos relieve pain partly by increasing the release of opiates and partly by increasing the release of dopamine. In contrast, antiplacebos or ____ (suggestions that the pain will increase) worsen pain by increasing anxiety.

Answer 19

nocebos

Question 20

Damaged or inflamed tissue, such as sunburned skin, releases histamine, nerve growth factor, and other chemicals that help repair the damage but also magnify the responses of nearby ____ and ____ receptors.

Answer 20

heat and pain

Question 21

Social pain. Hurt feelings do ____ physical pain in important regards.

Answer 21

resemble

Question 22

Experimenters monitored peoples brain activity during this task and found significantly increased activity in the cingulate cortex when someone ____ ___ ___. Recall the cingulate cortex responds to emotional aspects of pain.

Answer 22

felt left out

Question 23

Hurt feelings like real pain in another way, you can relieve hurt feelings with the pain-relieving drug ____ (Tylenol).

Answer 23

acetaminophen

Question 24

Researchers have identified special receptors for ____ and special spinal-cord pathways conveying ____.

Answer 24

itch

Question 25

You have at least two kinds of itch. They feel about the same, but the ____ are different.

Answer 25

causes

Question 26

The first type of itch, when you have mild ____ ____ – such as when your skin is healing after a cut – your skin releases histamines that dilate blood vessels and produce an itching sensation.

Answer 26

tissue damage

Question 27

The second type of itch, contact with certain ____ also produces itch. Antihistamines block the itch that histamines cause but not the itch that some plants cause.

Answer 27

plants

Question 28

A particular spinal-cord ____ conveys itch sensation. Some of its axons respond to histamine itch and some to plant itch.

Answer 28

path

Question 29

Itch axons activate certain neurons in the spinal-cord to produce a chemical called ____ ____. Blocking that peptide has been shown to decrease scratching in mice without affecting their responses to pain.

Answer 29

gastrin-releasing peptide

Question 30

Itch is useful because it directs you to scratch the itchy area and remove whatever is irritating your skin. Vigorous scratching produces ____ ____, and mild pain inhabits itch.

Answer 30

mild pain

Question 31

Opiates, which ____ pain, ____ itch. This inhibitory relationship between pain and itch is the strongest evidence that itch is not the type of pain.

Answer 31

decrease : increase