Pain fibers

Pain fibers, known as nociceptors, are specialized sensory neurons responsible for detecting noxious stimuli and transmitting pain signals to the central nervous system.

These fibers can be classified based on their diameter and degree of myelination.

Two main types: A-delta (Aδ) fibers and C fibers.

A-delta fibers are thinly myelinated and have a relatively fast conduction velocity.

A-delta fibers Are primarily responsible for transmitting sharp, acute pain sensations (pricking” or stabbing pains).

These fibers respond to intense mechanical and thermal stimuli, providing a rapid warning signal that prompts immediate withdrawal from the harmful stimulus.

C fibers, are unmyelinated and have a slower conduction velocity.

C fibers are associated with the transmission of dull, aching, and burning pain, often referred to as “slow” pain.

C fibers are polymodal, responding to a variety of noxious stimuli, including mechanical, thermal, and chemical stimuli.

This type of pain is typically more prolonged and can be associated with tissue damage and inflammation.

Nociceptors express various ion channels and receptors that are crucial for their function.

Nociceptors initiate pain signaling by detecting harmful stimuli through various ion channels and receptors on their nerve endings.
Transient receptor potential (TRP) channels such as TRPV1, TRPM8, and TRPA1 play crucial roles in detecting thermal and chemical stimuli.
Upon activation, these channels generate action potentials that travel along the afferent fibers to the dorsal horn of the spinal cord, where they synapse with secondary neurons and interneurons.
The complexity of nociceptor signaling involves various chemical mediators like substance P, histamine, bradykinin, and prostaglandins, which can sensitize nociceptors and enhance pain transmission.
This intricate system allows for significant modulation of pain signals at both peripheral and central levels, contributing to the diverse pain experiences observed clinically.

Transient receptor potential (TRP) channels such as TRPV1, TRPM8, and TRPA1 play significant roles in detecting thermal and chemical stimuli.

Additionally, voltage-gated sodium and calcium channels are essential for the generation and propagation of action potentials in these fibers.


Leave a Reply

Your email address will not be published. Required fields are marked *