1. C.Riedinger
Overview of somatosensory receptors
Receptive
Name Type Location Adaptation Task Afferent fibres
field
specialised
superficial
Meissner's corpuscle mechanoR small fast fine localisation of rapidly changing stimuli A-beta
(<keratin)
ending
specialised
deep (in fatty high frequency (300Hz) vibration
Pacinian corpuscle mechanoR large fast A-beta
layer) can't localise source
ending
specialised
superficial best at reading Braille
Merkel's disk mechanoR small slow A-beta
(<keratin) slowly moving stimulus
ending
specialised
deep (in fatty
Ruffini ending mechanoR large slow deep pressure A-beta
layer)
ending
free nerve
fires around 40*C
Hot temperature receptor ending, TRP slow AC
responds to capsaicin (chilli)
ion channels
free nerve
Cold temperature fires around 20*C
ending, TRP slow A-delta
receptor responds to menthol
ion channels
free nerve
Very cold temperature fires around 10*C
ending, TRP slow A-delta
receptor responds to isocyanates (wasabi)
ion channels
not specific=MULTIMODAL
respond to a wide range of ihigh threshold noxious
free nerve
Nociceptor sensitise!! (painful) stimuli, e.g. strong mechanical pressure, cold A-delta and AC
ending <15*C, heat >43*C, chemicals
sensitise to prolongued stimulus
embedded in group I=A-alpha
Proprioceptors muscle spindles
muscle fibres - fast detect the length of muscle (slow and fast
(muscle length) nuclear bag
1/1000 adapting)
embedded in
Proprioceptors muscle spindles group I and II=A-beta
muscle fibres - slow detect the length of muscle
(muscle length) nuclear chain (slow)
1/1000
Proprioceptors (stretch) tendons Ib (medium and fast)
in joint
Proprioceptors (joint) Ruffini type signal joint angle in extreme angles, not mid-way
capsule