The Nervous System: Sensory Systems

Vocabulary flashcards for The Nervous System: Sensory Systems lecture, covering somatosensory receptors, pathways, and pain perception.

Somatosensory System

The system responsible for processing sensory information from the body, including touch, temperature, pain, and proprioception.

Proprioceptors

Sensory receptors that provide information about the position and movement of body parts.

Mechanoreceptors

Sensory receptors that respond to mechanical stimuli such as pressure, touch, vibration, and stretch.

Thermoreceptors

Sensory receptors that detect changes in temperature.

Nociceptors

Sensory receptors that detect painful or potentially damaging stimuli.

Pacinian Corpuscle

A rapidly adapting mechanoreceptor that detects deep pressure and vibration.

Meissner's Corpuscle

A rapidly adapting mechanoreceptor that detects light touch and low-frequency vibration.

Hair Follicle Receptor

A rapidly adapting mechanoreceptor that detects movement of hairs.

Merkel's Disk

A slowly adapting mechanoreceptor that detects sustained pressure and touch.

Ruffini's Ending

A slowly adapting mechanoreceptor that detects skin stretch and sustained pressure.

Transient Receptor Potential (TRP) Ion Channels

Ion channels found in thermoreceptors and nociceptors that respond to temperature and some chemicals.

Warm Receptors

Free nerve endings that respond to temperatures in the range of 30

43

C, increasing frequency with temperature increase.

Cold Receptors

Free nerve endings that respond to temperatures in the range of 20

35

C, increasing frequency with temperature decrease.

Paradoxical Cold

The sensation of painfully hot experienced when cold receptors are activated by temperatures around 45

C.

A-delta Fibers

Thin, lightly myelinated nerve fibers associated with fast, sharp, and localized pain.

C Fibers

Thin, unmyelinated nerve fibers associated with dull, aching, and poorly localized slow pain.

Polymodal Nociceptors

Nociceptors that respond to multiple types of painful stimuli, including mechanical, extreme hot/cold, and chemicals.

Somatosensory Cortex

The area of the cerebral cortex dedicated to processing somatosensory information, organized topographically.

Homunculus

A distorted map representing the relative area of the cerebral cortex devoted to different body regions, proportional to sensitivity rather than size.

Dorsal Column

Medial Lemniscal Pathway

A neural pathway responsible for transmitting fine touch, vibration, pressure, and proprioception sensations; decussates in the medulla.

Decussation

The anatomical crossing over of nerve fibers from one side of the body to the other.

Spinothalamic Tract

A neural pathway responsible for transmitting pain and temperature sensations; decussates in the spinal cord.

Fast Pain

A sharp, pricking, and easily localized sensation transmitted by A-delta fibers.

Slow Pain

A dull, aching, and poorly localized sensation transmitted by C fibers.

Substance P

A neuropeptide neurotransmitter involved in the transmission of pain signals by first-order neurons.

Glutamate

An excitatory neurotransmitter involved in pain transmission in the spinal cord.

Visceral Pain

Pain originating from internal organs.

Referred Pain

Pain perceived at a location other than the site of the painful stimulus, often due to shared nerve pathways with somatic sensations.

Gate-Control Theory

A theory suggesting that non-painful input can close the 'gates' to painful input, preventing pain sensation from traveling to the central nervous system.

Endogenous Analgesia

The body's natural pain relief system, involving mechanisms that suppress pain signals.

Periaqueductal Gray Matter (PAG)

A brainstem region involved in modulating pain perception as part of the endogenous analgesia system.

Endogenous Opioids

Naturally occurring morphine-like substances (e.g., enkephalin) in the body that reduce pain by inhibiting neurotransmitter release or binding to opioid receptors.

Enkephalin

An endogenous opioid that can block the release of substance P from first-order neurons and act as a competitive inhibitor at opioid receptors.

Hyperalgesia

An increased sensitivity to pain or an enhanced painful response to a normally painful stimulus.

Phantom Limb Pain

Pain perceived in a missing limb, often due to activation of pain pathways for the limb or convergent stimulation from other sources.

Labeled Lines

The principle that each sensory receptor is 'tuned' to respond to a specific type of stimulus, and the brain interprets activity in that line as that specific sensation.