Somatosensory system Flashcards
Somatosensory receptors are the endings of nerve fibers and can be identified by?? (2)
Location
encapsulation
Hair follicles are innervated by……..
free nerve endings or more specialized endings
Hairy skin also has “soft touch” receptors that projects to…?
cortical regions associated with emotion and sexual arousal
In hairy skin hair, as the Meissner’s
corpuscles are absent, what replaces them?
hair follicle receptors
discriminative somatic sensation is the ability of
localization, intensity estimation, memory
The different receptors and afferents in fine touch can be defined physiologically by two main properties
adaptive rate
receptive field size
Differences in RF size reflect:
The spread of the terminals of the neuron
the sensitivity of ion channels
visco-elastic properties of the skin
Meissner corpuscles Large field or small field? Location Function Stimuli Adaptation Type of fibers
small field
Location: non-hairy skin close to the surface (fingertips, lips, eyelids, nipples and external genitalia).
Function: motion detection, grip control
Stimuli: skin motion, low-frequency vibration
Adaptation: rapid adaptation
type Aβ nerve fibers
receptive field: 22 mm^2
Merkel discs Large field or small field? Location Function Stimuli Adaptation Type of fibers
Small field Location: the tip of epidermal ridges Function: form and texture perception Stimuli: edges, points, corners, curvature Adaptation: slow adaptation type Aβ nerve fibers receptive field: 9 mm^2
Pacinian corpuscle: Large field or small field? Location Function Stimuli Adaptation Type of fibers
large field Location: dermis and deeper tissues Function: perception of distant events through transmitted vibrations; too use Stimuli: vibration (250 Hz is optimal) Adaptation: very rapid adaptation type Aβ nerve fibers receptive field: entire finger or hand
Ruffini corpuscle Large field or small field? Location Function Stimuli Adaptation Type of fibers
large field Location: dermis Function: tangential force; hand shape; motion detection Stimuli: skin stretch Adaptation: slow adaptation type Aβ nerve fibers receptive field: 60 mm^2
Small field tactile receptors?
Meissner corpuscles
Merkel discs
Large field tactile receptors?
Pacinian corpuscle
Ruffini corpuscle
Slowly adapting receptors?
Merkel discs
Ruffini corpuscle
free nerve endings
Fast adapting receptors?
Meissner’s corpuscle
Pacinian corpuscle
