chapter 5: the sensorimotor system Flashcards
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
stimulus
a physical event that triggers a sensory response
labeled lines
the concept that each nerve input to the brain reports only a particular type of information
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
sensory transduction
the process in which a receptor cell converts the energy in a into a change in the electrical potential across its membrane
Pacinian corpuscle or lamellate corpuscle
a skin receptor cell type that detects vibration and pressure
threshold
the stimulus intensity that is just adequate to trigger an action potential at the axon hillock
Meissner’s corpuscle or tactile corpuscle
a skin receptor cell type that detects light touch, responding especially to changes in stimuli
Merkel’s disc
a skin receptor type that detects light touch, responding especially to edges and isolated points on a surface
Ruffini corpuscle
a skin receptor cell type that detects stretching of the skin
free nerve ending
an axon that terminates in the skin and has no specialized cell associated with it; detect pain and/or changes in temperature
range fractionation
the means by which sensory systems covers wide range of intensity values as each sensory receptor cell specializes in just one part of the overall range of intensities
somatosensory system
a set of specialized receptors and neural mechanisms responsible for body sensations touch as touch and pain
receptive field
the stimulus region and features that affect the activity of a cell in a sensory system
adaptation
the progressive loss of receptor sensitivity as stimulation is maintained
phasic receptor
a receptor in which the frequency of action potentials drops rapidly as stimulation is maintained
tonic receptor
a receptor in which the frequency of action potentials declines slowly or not at all as stimulation is maintained
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
dorsal column system
a somatosensory system that delivers most touch stimuli via the dorsal columns of spinal white matter to the brain
dermatome
a strip of skin innervated by a particular spinal nerve
thalamus
the brain regions at the top of the brainstem that trade information with the cortex
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
non primary sensory cortex
for a given sensory modality, the cortical regions receiving direct projections from primary sensory cortex for that modality
also called second sensory cortex
primary somatosensory cortex or somatosensory 1 (S1)
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, is in the parietal lobe
polymodal neuron
a neuron upon which information from different sensory systems converges
synesthesia
a condition in which stimuli in one modality evoke the involuntary experience of an additional sensation in another modality
pain
the discomfort normally associated with tissue damage
nociceptor
a receptor that responds to stimuli (e.g., pain or changes in temperature) that produce tissue damage or pose the threat of damage
transient receptor potential 2 (TRP2)
a receptor, found in some free nerve endings, that opens its channel in response to rising temperatures
A delta (Ad) 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
anterolateral system or spinothalamic system
a somatosensory system that carries most of the pain information from the body to the brain