chapter 5 Touch and Pain Flashcards
somatosensory receptors in the skin that sense different aspects of touch
Pacinian and Meissen corpuscles, Merkel’s disks, and Ruffini endings.
All the somatosensory receptors have ___ that open in response to ____, triggering ____ that can be recorded experimentally by fine electrodes.
ion channels; mechanical deformation; action potential
Merkel’s disk responds well to ____.
a sustained indentation of the skin (sense pressure)
Ruffini endings respond to _____.
slowly changing indentations.
receptive field
the area of skin over which each individual receptor responds
___ has much larger receptive fields than___.
Pacinian corpuscles; Meissner’s corpuscles
once the receptors detect a stimulus…
they, in turn, send impulses along the sensory nerves that enter the dorsal roos of the spinal cord
the axons connecting touch receptors to the spinal cord are___.
large myelinated fibres that convey information from the periphery towards the cerebral cortex extremely rapidly.
temperature receptors also show ___.
adaption
somatosensory cortex
rely stations for touch in the medulla and the thalamus, before projection on to the primary sensory area in the cortex
the nerves cross the midline so that ___.
the right side of the body is represented in the left hemisphere and the left in the right
the input from the body is systematically mapped across the somatosensory cortex to form a
representation of the body surface
sensory homunculus
topographic representation of the sensory distribution of the body found in the cerebral cortex.
you can test this differential sensitivity across the body with the ___.
two-point discrimination test
two-point discrimination test
Bend some paper clips into a U-shape, some with a blindfold on, get a friend to touch various parts of your body with the tips of the paper clips.
the ability to perceive fine detail varies greatly across different parts of the body and is most highly developed in the tips of the ____.
fingers and lips
skin is sensitive enough to measure a raised dot that is less than___.
1/100th of a millimeter high
touch is not just a passive sense that responds, it is also involved in ___.
the active control of movement
neurons in the motor cortex
controlling the muscles in your arm that move your fingers get sensory input from touch receptors in the finger tips
active exploration
is crucial for the sense of touch
brain imaging is also starting to produce insights about___.
cortical plasticity by revealing that the map of the body in the somatosensory area can vary with experience
the ancient Greeks regarded pain as ___.
an emotion not a sensation
nociceptors
pain receptor, a sensory neuron that responds to damaging or potentially damaging stimuli by sending “possible threat” signals to the spinal cord and the brain.
nociceptors respond to heat ____.
above 46 degree celsius
