Understanding Pain Mechanisms

Front

What is pain according to the IASP?

Back

Pain is always subjective. If patients describe a sensation as pain, it should be considered pain.

Front

What are nociceptors?

Back

Nociceptors are free nerve endings that receive pain sensations from the skin and other tissues.

Front

What types of stimuli can activate nociceptors?

Back

Nociceptors can be activated by thermal (temperature), mechanical (e.g., stretch/strain), and chemical (e.g., pH change) stimuli.

Front

What are the two types of pain fibers and their characteristics?

Back

1. Myelinated A-delta fibers: Carry rapid, acute, sharp pain sensations (12-30 m/sec). 2. Unmyelinated C fibers: Carry slow, chronic pain sensations (0.5-1 m/sec).

Front

What is the difference between acute and chronic pain?

Back

Acute pain lasts for a short duration, while chronic pain lasts more than 3-6 months.

Front

What is central sensitization?

Back

Central sensitization is an increased responsiveness of nociceptors in the central nervous system to normal or sub-threshold afferent input, resulting in hypersensitivity to stimuli.

Front

What is referred pain?

Back

Referred pain is pain perceived at a location other than the site of the painful stimulus/origin.

Front

What is the role of the substantia gelatinosa (SG) in pain perception?

Back

The SG acts as a regulator (gate control) with presynaptic extensions over thick and thin-diameter afferents and T cells.

Front

What is the gate control theory?

Back

The gate control theory suggests that non-painful stimuli can close the gate to painful stimuli, reducing the perception of pain.

Front

What is allodynia?

Back

Allodynia is a condition in which a stimulus that is not normally painful causes pain.