Oof And Itch Flashcards
What does the somatic system depend on?
Nociceptors
Describe a nociceptor
Free, branching unmyelinated nerve endings that signal pain
Do nociceptors have the same path to the brain as mechanoreceptors?
Nope
What is nociception?
SEnsory process that provides signals that trigger pain
Can there be pain without nociception?
Yes, some throbbing sensations
What activates nociceptors?
Substances from damaged cells
- proteases
- ATP
- K+ channels
- histamines
What type of fibers are responsible for transduction of pain?
Unmyelinated C/Type 4
&
Thinly myelinated Adelta/Type 3
Nociceptors are ___modal
Poly
What is polymodal?
It can respond to several types of stimuli
What are the 3 types of things that can activate nociceptors?
Mechanical pressure, thermal pressure, and chemical pressure (like histamines)
What type of receptors control itch?
Pruriceptors
What type of fibers are used for the itch sensation?
C fibers
What channels are activated when histamine is present?
TRPV1 channels
Is all itch histamine mediated?
Nope
What type of fiber is used for the FIRSt pain? Describe it
Type 3/Adelta, fast and sharp
What type of fibers are used for SECOND pain? Describe it
C fiber activation, duller and longer lasting
Where do the second and first pain synapse to?
Substantial gelatinosa (basically the top left and right of the spinal butterfly)
What do 2nd order neurons do from the spine?
Decussate and ascend
What is the main neurotransmitter of pain afferents?
Glutamate
Which pathway do pain and temperature take to get to S1?
Spinothalamic
Where do the axons decussate in the spinothalamic pathway? And ascend via what?
Spinal cord, the spinALthalamic pathway
Do fibers in the spinothalamic pathway synapse anywhere before getting to S1?
No
What is the Gate Theory of Pain?
Why rubbing an injury is done
What is the projection neuron inhibited by?
An interneuron
What is an interneuron excited by?
Large sensory axons
What happens when mechanoreceptors axon signals simultaneously with nociceptors?
Nociception suppressed
What is referred pain?
Pain felt somewhere different from injury site (ex. Heart attack you can feel pain in your sides or jaw)
What causes referred pain?
Two areas axons being close together in dorsal horn
I have a headache
Same
