Chapter 12: General Sensation - Vocabulary Flashcards

Vocabulary flashcards covering key terms from Chapter 12: General Sensation (sensory receptors, modalities, pathways, and aging).

Sensation

The process by which sensory receptors respond to stimuli and transmit information to the CNS; includes modalities like touch, temperature, proprioception, nociception, and visceral sensations.

Perception

The brain's interpretation and meaning assigned to sensory input.

Exteroceptors

Receptors that respond to stimuli originating outside the body; located near body surfaces (e.g., skin).

Interoceptors

Receptors that monitor internal conditions; visceral interoceptors detect changes in internal organs; somatic interoceptors detect body interactions with the environment.

Thermoreceptors

Receptors that detect changes in temperature.

Chemoreceptors

Receptors that detect chemical changes (e.g., blood gases and pH).

Mechanoreceptors

Receptors that respond to mechanical stimuli such as pressure, touch, vibration, stretch, and proprioception; include baroreceptors, osmoreceptors, and proprioceptors.

Nociceptors

Pain receptors that detect tissue damage or noxious stimuli; typically slow-adapting and concentrated where injury is likely.

Free nerve endings

Unencapsulated nerve endings that detect temperature, touch, pressure, stretch, and tissue damage; vary in adaptation.

Merkel cells

Oval-shaped mechanoreceptors in fingertips and lips; detect fine touch and texture; slowly adapting for steady touch.

Meissner's corpuscles

Encapsulated nerve endings in dermal papillae; sensitive to light touch and low-frequency vibrations; rapidly adapting; concentrated in fingertips and lips.

Ruffini corpuscles

Encapsulated endings intertwined with collagen; detect skin stretch; contribute to grasp; found deep in dermis; little adaptation.

Krause’s corpuscles

Small encapsulated mechanoreceptors in dry skin and mucous membranes; detect pressure and cold.

Pacinian corpuscles

Encapsulated nerve endings with concentric layers; deep in dermis; detect deep pressure and vibration; very rapidly adapting.

Proprioceptors

Receptors that sense body position and movement; essential for coordination.

Osmoreceptors

Receptors that sense changes in osmolarity; regulate fluid balance.

Baroreceptors

Receptors that detect changes in blood pressure; help regulate BP.

TRP channels

Transient receptor potential cation channels that open at different temperatures, allowing Ca2+ entry to detect temperature changes.

Receptor potential

Graded depolarization or hyperpolarization produced in a receptor in response to a stimulus; can summate to trigger an action potential.

Action potential

All-or-none electrical impulse that travels along the axon when threshold is reached.

Recruitment

Stronger stimuli activate more sensory units or increase firing frequency, increasing perceived intensity.

Range fractionation

Subsets of receptors respond to distinct ranges of stimuli, expanding the dynamic range.

Lateral inhibition

Neural mechanism where activated neurons inhibit neighboring neurons to sharpen perception and localization.

Dorsal column pathway

Somatosensory pathway for fine touch and proprioception; first-order in dorsal root ganglion; ascends in dorsal columns to medulla; second-order in medulla; third-order in thalamus; to somatosensory cortex.

Anterolateral pathway

Pathway for pain and temperature; decussates in spinal cord; first-order in dorsal root ganglion; second-order in dorsal horn; third-order in thalamus; to somatosensory cortex.

First-order neuron

Neuron with cell body in the dorsal root ganglion; peripheral processes extend to receptors and central processes enter the spinal cord.

Second-order neuron

Neuron in brainstem or spinal cord that receives input from the first-order neuron and sends to the thalamus; may cross (decussate).

Third-order neuron

Neuron in the thalamus that projects to the somatosensory cortex.

Dorsal root ganglion

Cluster of sensory neuron cell bodies located near the spinal cord; site of first-order neurons.

Somatosensory cortex

Cerebral cortex region that processes sensory information from the body; located in the parietal lobe.

Analgesics

Drugs that modify perception of pain (e.g., NSAIDs).

Anesthetics

Drugs that reversibly block action potential generation in primary afferent fibers by blocking voltage-gated Na+ channels (e.g., lidocaine).

Endogenous opioids

Body-produced opioids (e.g., beta-endorphins, enkephalins, dynorphins) that modulate pain signaling.

Synthetic opioids

Man-made opioids (e.g., morphine) that inhibit pain transmission at central synapses.

Anticonvulsants

Medications effective for neuropathic pain (e.g., carbamazepine).

Analog-to-digital conversion

Process by which graded receptor potentials are converted into all-or-none action potentials in neurons.

Visceral pain

Pain arising from internal organs; often poorly localized and may refer to other areas.

Fast pain

Sharp, well-localized pain carried by A-delta fibers.

Slow pain

Dull, diffuse pain carried by C fibers.

Acute pain

Pain with a sudden onset and protective function, usually short-term.

Chronic pain

Pain persisting beyond normal healing time, often long-term.

Aging of sensory receptors

Age-related decline in sensory sensitivity: higher thresholds, slower adaptation, reduced chemoreceptor sensitivity, and decreased pain sensitivity.