Chapter 49-Somatic sensations II Flashcards
Explain the difference between fast and slow pain.
fast pain is felt within 0.1 sec and is sharp vs. slow pain which is felt after 1 sec and is throbbing, aching pain`
What are other names for the fast pain?
Sharp pain, pricking pain, acute pain, electric pain.
What are other names for the slow pain?
Aching pain, throbbing pain, nauseous pain, chronic pain.
Wher is the fast pain felt?
Fast pain is mostly felt on the skin.
Where is the slow pain felt?
Occurs in both skin and almost any deep tissue organ.
What are pain receptors?
Free nerve endings
Where are the free nerve ending pain receptors widespread?
Superficial layers of the skin and in certain internal tissues, such as the periosteum, arterial walls, joint surfaces, and falx and tentorium in the cranial vault
Which stimuli can elicit pain?
Mechanical, thermal, chemical
Which stimuli can elicit fast pain?
Mechanical and thermal
Which stimuli can elicit slow pain?
Mechanical, thermal, and chemical
Which chemicals excite pain receptors?
Bradykinin, serotonin, histamine, potassium ions, acids, acetylcholine, and proteolytic enzymes
Which chemicals enhance the sensitivity of pain receptors?
Prostaglandins and substance P
True or false: pain receptor can readily adapt to stimuli
False, in fact sometimes the sensitivity can actually increase as the pain progresses (hyperalgesia)
Hyperalgesia
Increased sensitivity of the pain receptors.
True or false: the tissue damage that has already occurred is the primary influencer of pain.
False, the rate of tissue damage is the most important determining factor of pain felt.
What is the temperature at which an average human starts to feel pain?
Above 45°C.
This chemical causes the most pain and may be the single most responsible for causing the tissue damage type of pain.
Bradykinin (also local increase in potassium ions and action of enzymes can contribute to pain.
Can ischemia be a cause of pain?
Yes, it can be; the time that is needed for the pain to be felt depends on the metabolism of the tissue; the main chemical is thought to be lactic acid (anaerobic respiration).
Which factors contribute to pain caused by muscle spasms?
Direct effect of the spasms in the pain felt by mechanosensitive receptors; indirectly the contraction of muscles causes compression of blood vessels, thus ischemia; spasms also increase the metabolic rate, worsening ischemia.
What is the fiber transmission for fast, sharp pain?
Elicited by mechanical or thermal pain stimuli; transmitted in the peripheral nerves to the spinal cord by small type A-delta fibers at velocities between 6-30 m/sec
What is the fiber transmission for slow, chronic type pain?
Elicited mostly by chemical (can be mechanical or thermal stimuli); transmitted to the spinal cord by type C fibers at velocities between 0.5-2 m/sec
What is a “double-pain” sensation?
Sharp pain is transmitted to the brain via A-delta fibers, followed by a second later by a slow pain, conducted via type C fivers.
