Senses and Pain Flashcards
Mechanorecptor
What senses it is associated with
How it works
what is the sense organ
hearing and balance
fluid is “bent” to activate sensory neurons and enables the sense of sound and balance
ear and inner ear
Proprioceptor
what sense it is associated with
what is the sense organ
Awareness of body in its space
Inner ear, and receptors in joints and ligaments
Osmoreceptor
what sense it is associated with
what is the sense organ
thirst
hypothalamus
Photorecptor
What senses it is associated with
How it works
what is the specific receptor
vision
light
rods and cones
Nociceptor What senses it is associated with How it works what is the sense organ what is the specific receptor
Pain
Transduction, transmission, perception, modulation
peripheral NS
Fast A and Slow C
Where are there nociceptors in the body?
Which area has more and why?
skin, muscles, joints, arteries, viscera
skin (most), muscles, joints because these ares experience the most tissue damage
what type of stimuli do nociceptors respond to?
chemical, mechanical, thermal
Large A
Signal speed
pain manifestation
activated by what type of stimuli
myelinated (fast)
large fibers
precise, localized, sharp
temp, vibration, pressure (decreases with age)
Small C
Signal speed
pain manifestation
activated by what type of stimuli
unmyelinated (slow)
small fibers
dull, achy, continuous
blunt force
Pain pathway
1) Transduction: damaged tissue (mechanical, thermal, chemical) activates Prostagandins and Bradykinins activating an action potential and release of nociceptors
2) Transmission: sending nociception from the site through sensory neurons A and C, then spinal cord, then the brain stem, then thalamus, then cortex
3) Perception: when nociception reaches the outer grey cortex and you become aware of the pain (from either A or C)
4) Modulation: reduce and turn down the transmission of the perception of pain.
During transmission, what can be targeted to stop the pain pathway
the result being that you do not feel pain
Nociceptors A and C synapse (“gate”) to the neuron in the thalamus
targeting opioid receptors
pain tolerance vs pain threshold
Tolerance: the amount of pain you can tolerate w/o it affecting your day to day life. Very individual! Depends on the person, culture, gender, etc.
Threshold: how much stimulation it takes for you to feel pain. More normalized from person to person
Pain modulation:
Endogenous modulation
- comes from within the body
- release endorphins that bond with opioid receptors throughout the body
-endogenous opioids bind with opioid receptors in the periphery, spinal cord and brain to inhibit pain
Pain modulation:
Exogenous modulation
-Comes from outside the body; eg: ice pack, heat pad, massage (all A nocicoceptors)
Example: hit your elbow and it hurts; dull, achy, long lasting. You instinctively rub your elbow to “beat” the C nociceptor signal with A nociceptors (massage)
Characteristics of acute pain
transient
begins suddenly
relieved after pain stimulus is removed
self-limiting
