Touch and Pain

Question 1

Touch is the sense by which we determine

Answer 1

the characteristics of objects: size, shape, and texture.

Question 2

How do we touch

Answer 2

through touch receptors in the skin. In hariy skin areas some receptors consist of webs of sensory nerve cell ndings wrapping around the base of hairs

Question 3

Signals from touch receptors pass via sensory nerves to the spinal cord where they

Answer 3

synapse (make contact) with other nerve cells in which in thurn they send the information to the thalamus

Question 4

The transmission of this information is highly topographic meaning that

Answer 4

the body is represented in an orderly fashion at levels at different levels of teh nervous system

Question 5

Large areas of the cortex are devoted to sensations from the

Answer 5

hands and lips, much smaller cortical regions represent less sensitive parts of the bdoy

Question 6

Different parts of the boyd vary in thier sensitivity to tactile and painful stimuli acrding to

Answer 6

the number and distribution of receptors.

Question 7

Neurologists measure sensitivity by determinging the patients

Answer 7

two point threshod, the methond involvings touching the skin with calipers at two points. The two point threshold is the distance between the two points that is necessary for the indiviudal to distinguishtwo stimuli from one

Question 8

The thrshold is lowest where?

Answer 8

On the finger and lips

Question 9

Until recently, pain was thought to represent a simple message resulting from neurons sending

Answer 9

electrical impulses froma site of injury directly to the brain

Question 10

What do we now know?

Answer 10

That the process is very complicated

Question 11

Nerve impulses from sites of injury can persist for how long

Answer 11

hours, days or longer

Question 12

What can persistantinjury lead to?

Answer 12

Changes in the nervous system that amplify and prolong the pain signla

Question 13

When the pain signal is proloned, the result is astate of hypersensitivity in which pain persists and can be evoked by

Answer 13

normally innocuous stimuli

Question 14

Until recently, what was pain thought to be

Answer 14

a simple message from neurons from an electrical thing

Question 15

What cana persistan tinjury lead to ?

Answer 15

Changes in the nervous system that amplify and prolong pain signal

Question 16

The sensory fibers that respond to stimuli and that damage ttissue are called what?

Answer 16

nociiceptors

Question 17

Different nociceptor subsets express molecules that are

Answer 17

responsible to painful, thermal of chemical stimuation

Question 18

The same molecules can respond to plant derived chamicals fomr

Answer 18

capsaicin, garlic and wasabi

Question 19

Tissue injury also can cause the elease of chemicals like

Answer 19

prostaglandins, to enhance the sensitivity of receptos to tissue damage nad ultimately can induce more pain sensation

Question 20

What is allodynia

Answer 20

in which innocuous simuli can produce ain

Question 21

Where are pain messages transmitted to?

Answer 21

the spinal cord via small, myelinated fibers nad C fibers- very small unmyelinated fibers

Question 22

The small myelinated pain sensitive nerve fibers evoke what?

Answer 22

The fastest, sharpest pain that is produced

Question 23

What is C-Fiber pain

Answer 23

dull

Question 24

In the ascending system, what happnes to impulses,

Answer 24

they are relayed from the spinal cord to several brain structures including the thalamus and cerebral cortex which is involved in the proces by which pain messages become a concious experiences

Question 25

The experience of pain is not just as

Answer 25

funciton of the magnitude of the injury or even the intensity of impulse activty generated by injury

Question 26

Pain messages can be suppressd by

Answer 26

systems of neurons that originate within the gray matter in the brainstem.

Question 27

The descending systems suppress the transmission of pain signals from the dorsal horn of the spinal cord to higher brain centers.

Question 28

What do some of the descending system sue?

Answer 28

They use naturally ocuring chemicals, the endogenous opioids or endorphins which are funtionally smilar to morphine