Nervous control system, PAIN (physiology) Flashcards
What is pain?
It is an unpleasant sensory or emotional experience associated with actual or potential tissue damage, or described in terms of such damage.
List three functions of pain
-Protection of tissue.
-Alerts you of any tissue damage.
-Activation of pain escape mechanisms.
Name and differentiate btwn the two types of pain
•Fast pain:
-detected by myelated A fibres.
-perception occurs rapidly.
-stimulus causes a sharp, bright localised pain.
- not felt in deeper tissues.
•Slow pain:
-detected by unmyelated c fibres.
-perception slow and gradual.
-causes dull, intense, diffuse unpleasant feeling.
What is the difference btwn physiologic and pathologic pain?
Physiologic pain has a sudden onset and can be receded during the healing process.
Pathologic pain is caused by nerve injury due to toxins, ischemia or diabetes.
Three classifications of pain according to its location(6)
•Superficial somatic pain-pain on the skin surface such is pricking, burning.
•Deep pain- pain is felt in skeletal muscles, joints, tendons, fascia.
•Visceral pain- pain in the visceral organs.
What is referred pain?
Irritation on a visceral organ but the pain is felt at a distant somatic structure.
What is phantom pain?
When you are feeling pain where the missing body part should be.
What are the components needed for pain perception? (5)
-Nociceptors
-Primary afferent neuronal pathways
-Dorsal horn of the spinal cord
-Ascending tracts of the brain
-Descending pathways
What are nociceptors?
Sensory receptors that respond to potentially damaging stimuli.
Where are nociceptors commonly found? (4)
-In joint capsules
-In the superficial portion of skin
- In the periostea of bones
- Around the walls of blood vessels
What are nociceptors sensitive to? (3)
-Temperature extremes
-Mechanical injury
-Dissolved chemical, such as chemicals released by injured cells.
Four types of nociceptors and what they respond to.
Mechanical- respond to strong pressure.
Chemical- respond to chemicals such as histamine, bradykinin.
Thermal- Responds to very hot or cold temperatures.
Polymodal- respond to combinations of stimuli.
Which substances does the injured tissue release during an injury? (3)
Substance P, bradykinin and potassium.
What do mast cells release during an injury?
Histamine
What are other substances released during an injury?
-Serotonin, Ach, prostaglandins and leukotrienes, ATP.