Chapter 8 Flashcards & Key Terms

acupuncture
The insertion of needles at designated points on the skin to alleviate pain or neurological malfunction.
adaptation
The progressive loss of receptor sensitivity as stimulation is maintained.
adequate stimulus
The type of stimulus for which a given sensory organ is particularly adapted.
analgesia
Absence of or reduction in pain.
anterolateral system or spinothalamic system
A somatosensory system that carries most of the pain information from the body to the brain.
attention
A state or condition of selective awareness or perceptual receptivity, by which specific stimuli are selected for enhanced processing.
Aδ fiber
A moderately large, myelinated, and therefore fast-conducting, axon, usually transmitting pain information.
C fiber
A small, unmyelinated axon that conducts pain information slowly and adapts slowly.
capsaicin
A compound synthesized by various plants to deter predators by mimicking the experience of burning.
central modulation of sensory information
The process in which higher brain centers, such as the cortex and thalamus, suppress some sources of sensory information and amplify others.
cingulate cortex
Also called cingulum. A region of medial cerebral cortex that lies dorsal to the corpus callosum.
coding
The rules by which action potentials in a sensory system reflect a physical stimulus.
congenital insensitivity to pain
The condition of being born without the ability to perceive pain.
cool-menthol receptor 1 (CMR1)
Also called TRP8. A sensory receptor, found in some free nerve endings, that opens an ion channel in response to a mild temperature drop or exposure to menthol.
dermatome
A strip of skin innervated by a particular spinal root.
dermis
The middle layer of skin, between the epidermis and the hypodermis.
dorsal column system
A somatosensory system that delivers most touch stimuli via the dorsal columns of spinal white matter to the brain.
dynorphins
One of three kinds of endogenous opioids.
endogenous opioids
A family of peptide transmitters that have been called the body’s own narcotics. The three kinds are enkephalins, endorphins, and dynorphins.
endorphins
One of three kinds of endogenous opioids.
enkephalins
One of three kinds of endogenous opioids.
epidermis
The outermost layer of skin, over the dermis.
free nerve ending
An axon that terminates in the skin without any specialized cell associated with it and that detects pain and/or changes in temperature.
gastrin-releasing peptide (GRP)
A neuropeptide that stimulates neurons in the dorsal horn to provide the sensation of itch.
generator potential
A local change in the resting potential of a receptor cell that mediates between the impact of stimuli and the initiation of action potentials.
glutamate
An amino acid transmitter, the most common excitatory transmitter.
hypodermis
Also called subcutaneous tissue. The innermost layer of skin, under the dermis.
labeled lines
The concept that each nerve input to the brain reports only a particular type of information.
Meissner's corpuscle
A skin receptor cell type that detects light touch.
Merkel's disc
A skin receptor cell type that detects light touch.
naloxone
A potent antagonist of opiates that is often administered to people who have taken drug overdoses. It binds to receptors for endogenous opioids.
neuropathic pain
Pain caused by damage to peripheral nerves; often difficult to treat.
nociceptor
A receptor that responds to stimuli that produce tissue damage or pose the threat of damage.
opiates
A class of compounds that exert an effect like that of opium, including reduced pain sensitivity.
opioid receptor
A receptor that responds to endogenous and/or exogenous opioids.
opioids
A class of peptides produced in various regions of the brain that bind to opioid receptors and act like opiates.
Pacinian corpuscle
A skin receptor cell type that detects vibration.
pain
The discomfort normally associated with tissue damage.
periaqueductal gray
The neuronal body–rich region of the midbrain surrounding the cerebral aqueduct that connects the third and fourth ventricles; involved in pain perception.
phasic receptor
A receptor in which the frequency of action potentials drops rapidly as stimulation is maintained.
placebo
A substance, given to a patient, that is known to be ineffective or inert but that sometimes brings relief.
polymodal
Involving several sensory modalities.
primary sensory cortex
For a given sensory modality, the region of cortex that receives most of the information about that modality from the thalamus or, in the case of olfaction, directly from the secondary sensory neurons.
primary somatosensory cortex (S1) or somatosensory 1
The gyrus just posterior to the central sulcus where sensory receptors on the body surface are mapped. Primary cortex for receiving touch and pain information, in the parietal lobe.
range fractionation
A hypothesis of stimulus intensity perception stating that a wide range of intensity values can be encoded by a group of cells, each of which is a specialist for a particular range of stimulus intensities.
receptive field
The stimulus region and features that affect the activity of a cell in a sensory system.
receptor cell
A specialized cell that responds to a particular energy or substance in the internal or external environment, and converts this energy into a change in the electrical potential across its membrane.
Ruffini's ending
A skin receptor cell type that detects stretching of the skin.
secondary sensory cortex or nonprimary sensory cortex
For a given sensory modality, the cortical regions receiving direct projections from primary sensory cortex for that modality.
secondary somatosensory cortex (S2) or somatosensory 2
The region of cortex that receives direct projections from primary somatosensory cortex.
sensory pathway
The chain of neural connections from sensory receptor cells to the cortex.
sensory receptor organ
An organ (such as the eye or ear) specialized to receive particular stimuli.
sensory transduction
The process in which a receptor cell converts the energy in a stimulus into a change in the electrical potential across its membrane.
somatosensory
Referring to body sensation, particularly touch and pain sensation.
specific nerve energies
The doctrine that the receptors and neural channels for the different senses are independent and operate in their own special ways, and can produce only one particular sensation each.
stimulus
A physical event that triggers a sensory response.
substance P
A peptide transmitter implicated in pain transmission.
synesthesia
A condition in which stimuli in one modality evoke the involuntary experience of an additional sensation in another modality.
tactile
Of or relating to touch.
thalamus
The brain regions at the top of the brainstem that trade information with the cortex.
threshold
The stimulus intensity that is just adequate to trigger an action potential at the axon hillock.
tonic receptor
A receptor in which the frequency of action potentials declines slowly or not at all as stimulation is maintained.
transcutaneous electrical nerve stimulation (TENS)
The delivery of electrical pulses through electrodes attached to the skin, which excite nerves that supply the region to which pain is referred. TENS can relieve the pain in some instances.
transient receptor potential 2 (TRP2)
A receptor, found in some free nerve endings, that opens its channel in response to rising temperatures.
transient receptor potential vanilloid type 1 (TRPV1)
Also called vanilloid receptor 1. A receptor that binds capsaicin to transmit the burning sensation from chili peppers and normally detects sudden increases in temperature.
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