Somatosensory physiology Flashcards
How is the distribution of somatosensory receptors different from other sensations?
Somatosensory receptors are distributed throughout the body (other systems’ receptors are clustered)
What are the four main classes of somatosensory receptors?
tactile
proprioception
thermal sensations
nociceptive (painful)
Which two mechanoreceptors sit in the dermal-epidermal boundary?
Meissener’s corpuscles and Merkel’s disks
Describe the morphology of Meisseners corpuscles
looping axon terminals that inter-twine supporting cells
What do Meisseners corpuscles receive?
low frequency vibrations
Describe the morphology or Merkel’s disks
dome structure atop axon terminals
What type of sensation do Merkel’s disks receive?
small forms and shapes
Describe the morphology of pacinian corpuscles
sensory axon surrounded by fluid filled capsule, onion shaped appearance
What type of sensation are pacinian corpuscles responsible for?
high frequency vibrations
What type of sensation are ruffini endings responsible for?
pressure
What type of sensation are nociceptors responsible for?
noxious/harmful pain
Describe the morphology of ruffini ending
nerve terminals intertwined with collagen fibrils
Describe the morphology of nociceptors
free nerve endings that penetrate epithelial cells (no morphogological specialisation)
Which mechanoreceptors are classed as slow adapting?
Merkel’s disks and ruffini endings
Which mechanoreceptors are classed as fast adapting?
Meissener’s corpuscles and pacinian corpuscles
Which mechanoreceptors have small receptive fields?
Meissener’s corpuscles and Merkel’s disks
Which mechanoreceptor has the smallest receptive field size?
Merkel’s disks
Which mechanoreceptors have large receptive fields?
Pacinian’s corpuscles and ruffini endings
Which sensation is the most prioritized by the brain (which travels fastest)?
proprioception
What is astereoagnosia?
inability to identify objects on basis of touch alone
What is neglect syndrome?
body part or visual field is disregarded
