BIOL4100: SOMATIC SENSORY SYSTEM EXAM QUESTIONS AND
ANSWERS WITH COMPLETE SOLUTIONS VERIFIED LATEST
UPDATE
Skin Layers
Epidermis, dermis, and subcutis
Parts of the Skin
Meissner corpuscle, merkel cell neurite complex, ruffini ending, sweat gland, and
pacinian corpuscle
Mechanoreceptors of the Skin
Unmyelinated axon branches with mechanosensitive ion channels
Pacinian Corpuscles
Deep in dermis, up to 2mm long and 1 mm diameter, and have highest density in the
fingers
Ruffini's Endings
Smaller than pacinian corpuscles
Meissner's Corpuscles
1/10th size of pacinian corpuscles and is found in ridges of glabrous skin
Merkel's Disks
Consist of a nerve terminal and a flattened, non-neural epithelial cell, concentrated
where spatial acuity is highest
Pacinian Corpuscles Responds To
Vibrations of frequency 10-500 Hz
, Ruffini's Endings Responds To
Stretch of frequency 15-400 Hz and is best for providing information about finger
position
Meissner's Corpuscles Responds to
Touch, specifically flutter and indentation of frequency 3-40 Hz, and is best for stable
grasp
Merkel's Disks Respond To
Touch, specifically slow pushing and indentation of frequency 0.3-3 Hz, and is best for
texture perception, pattern, and form perception
Krause End Bulbs
Very sensitive, located around lips and genitals
Differences in Stimulus Responses
Merkel's for surface details, Meissner for coarser appraisal, and Pacinian and Ruffini for
tracking movement and position of finger
Two-Point Discrimination
Ability to distinguish the separation of two simultaneous pinpricks on the skin
Why Fingers are Good
higher density of mechanoreceptors, small receptive fields, more brain tissue per
square mm, and special high-resolution discrimination mechanisms
Two-Point Touch Threshold
When points are applied at different sites on the body
Tactile Sensitivity
Declines with age, except in blind people
ANSWERS WITH COMPLETE SOLUTIONS VERIFIED LATEST
UPDATE
Skin Layers
Epidermis, dermis, and subcutis
Parts of the Skin
Meissner corpuscle, merkel cell neurite complex, ruffini ending, sweat gland, and
pacinian corpuscle
Mechanoreceptors of the Skin
Unmyelinated axon branches with mechanosensitive ion channels
Pacinian Corpuscles
Deep in dermis, up to 2mm long and 1 mm diameter, and have highest density in the
fingers
Ruffini's Endings
Smaller than pacinian corpuscles
Meissner's Corpuscles
1/10th size of pacinian corpuscles and is found in ridges of glabrous skin
Merkel's Disks
Consist of a nerve terminal and a flattened, non-neural epithelial cell, concentrated
where spatial acuity is highest
Pacinian Corpuscles Responds To
Vibrations of frequency 10-500 Hz
, Ruffini's Endings Responds To
Stretch of frequency 15-400 Hz and is best for providing information about finger
position
Meissner's Corpuscles Responds to
Touch, specifically flutter and indentation of frequency 3-40 Hz, and is best for stable
grasp
Merkel's Disks Respond To
Touch, specifically slow pushing and indentation of frequency 0.3-3 Hz, and is best for
texture perception, pattern, and form perception
Krause End Bulbs
Very sensitive, located around lips and genitals
Differences in Stimulus Responses
Merkel's for surface details, Meissner for coarser appraisal, and Pacinian and Ruffini for
tracking movement and position of finger
Two-Point Discrimination
Ability to distinguish the separation of two simultaneous pinpricks on the skin
Why Fingers are Good
higher density of mechanoreceptors, small receptive fields, more brain tissue per
square mm, and special high-resolution discrimination mechanisms
Two-Point Touch Threshold
When points are applied at different sites on the body
Tactile Sensitivity
Declines with age, except in blind people
