Touch and Pain

These flashcards cover key vocabulary related to the sensory systems of touch and pain and their implications for understanding these sensations.

A-fibers

Fast-conducting sensory nerves with myelinated axons that have larger diameter and thicker myelin sheaths to increase conduction speed.

Allodynia

Pain due to a stimulus that does not normally provoke pain, such as when a light touch feels painful.

Analgesia

Pain relief.

C-fibers

Slow-conducting unmyelinated thin sensory afferents responsible for conveying noxious, thermal, and heat signals; includes C-tactile fibers that convey gentle touch.

Chronic pain

Persistent or recurrent pain beyond the usual course of acute illness or injury, sometimes present without observable tissue damage.

Cutaneous senses

The senses of the skin: tactile, thermal, pruritic (itchy), painful, and pleasant.

Descending pain modulatory system

A top-down system that can inhibit or facilitate pain, producing analgesia through endogenous opioid release.

Endorphin

An endogenous morphine-like peptide synthesized in the nervous system that binds to opioid receptors.

Exteroception

The sense of the external world; all stimulation originating from outside the body.

Interoception

The sense of the physiological state of the body, relevant to homeostasis, including sensations like pain and hunger.

Nociception

The neural process of encoding noxious stimuli and sending information about tissue damage to the brain.

Nociceptors

High-threshold sensory receptors that transduce and encode noxious stimuli to signal potential tissue damage.

Noxious stimulus

A damaging stimulus threatening normal tissue.

Social touch hypothesis

Proposes that social touch is a distinct domain of touch characterized by C-tactile afferents that convey social-affective information.

Pain

An unpleasant sensory and emotional experience associated with actual or potential tissue damage.

Phantom pain

Pain that appears to originate in an amputated limb.

Placebo effect

Effects from a treatment not caused by the treatment's physical properties but by the meaning assigned to it.

Sensitization

Increased responsiveness of nociceptive neurons to normal input and recruitment of responses to normally subthreshold inputs.

Somatosensory cortex

The primary sensory cortex in the postcentral gyrus and secondary somatosensory cortex, responsible for processing somatosensory information.

Transduction

The mechanism that converts stimuli into electrical signals processable by the nervous system.

Chronic pain conditions

Pain that persists after the usual recovery period, often due to nerve injury or altered sensitivity.

Motivation–decision model

A model describing how the brain continuously evaluates pros and cons, influencing pain perception.

C-tactile fibers

A subtype of C-fibers that responds to gentle touch and conveys social-affective relevance.