Pain Flashcards
Nociceptors
neurons detecting pain sensation
How does the sense of pain travel?
Nociceptors detect stimuli through free nerve endings and project to the periphery, where their receptor endings are detecting the sensory stimuli and to the spinal cord where they will eventually transmit the signal to other neurons.
The afferent neurons sensing pain are different from the ones sensing touch or proprioception. How are they different?
- They have free nerve endings
- They have a different name
- they are thinner
there are of 2 types of afferent neurons sensing pain
- Adelta are myelinated, hence thicker and faster
2. C are unmyelinated, hence thinner and slower
Nociceptors are different from somatosensory receptors.
They are different cells that are activated only when the sensory stimulus should be painful. They have a different sensitivity to temperature
Perception of pain usually happens in 2 steps:
- fast sharp pain,
2: slow, diffuse, long lasting pain.
These are mediated by
1. the fast Adelta fibers
and
2. the slow C fibers.
The pain signals are being detected by very special types of receptors on the nociceptor neurons
These include the TRP channels.
TRP channels are cations (Ca2+, Na+) permeable.
Pain fibers have a very particular type of voltage gated sodium channel called?
Nav1.7 which is very important for their action potential.
TRP channels are
important for the transduction of nociception and can detect temperature, mechanical or chemical insults
Parallel pain pathways are
- Sensory-discriminative involving the spinothalamic tract
2. Affective-motivational involving many brain areas
Central sensitization
Refers to the increase of the excitability of neurons in the dorsal horn following high levels of activity in the nociceptive afferents.
