Cutaneous receptors (365/351) Flashcards
define mechanotransduction
process where mechanical energy is converted into a voltage change in sensory afferent neurons
what is a receptive field
region of the skin that is capable of evoking APs in a given cutaneous afferent
which type of receptor has one large receptive field
type 2 deep receptors (one cell to one neuron)
what type of receptor has multiple hotspots in its receptive field
type 1 superficial receptors (multiple cells attached to one neuron)
which two cells are type 1 superficial receptors
SA1 - merkel cell
FA 1 - meissners corpuscle
which two cells are type 2 deep receptors
SA2 - ruffini endings
FA2 - pacinian corpuscles
which two cells are fast adapting
FA1 - meissners corpuscle
FA2 - pacinian corpuscle
which two cells are slow adapting
SA1 - merkel cells
SA2 - ruffini endings
which receptor is not present in non human primates (and allows us to walk on 2 feet instead of 4)
SA2 - ruffini endings
what is the merkel cell - neurite complex
merkel cell and the sensory neuron it synapses with
which two receptors are highly concentrated in the fingertips
SA1 - merkel cells
FA1 - meissners corpuscle
which two receptors have equally distributed innervation density
SA2 - ruffini endings
FA2 - pacinian corpuscle
which receptor responds to edges and curvature
SA1 - merkel cells
which receptor responds to slippage and motion across skin
FA2 - meissner corpuscles
which receptor is most sensitive to skin stretch
SA2 - ruffini endings
which receptor is most sensitive to change in indentation rate (acceleration) and high frequency vibration
FA2 - pacinian corpuscles
rank the 4 receptors on mean mechanical threshold from high to low
high (300um) - SA2 ruffini endings
moderate (30um) - SA1 merkel cells
low (6um) - FA1 meissner corpuscle
extreme low (0.08um) - FA2 pacinian corpuscle
what happens with FA1 and FA2 as vibration frequency increases from 30-200 Hz)
meissner (FA1) firing rate increases until 50Hz and then firing rate remains the same at any frequency past 50Hz
- pacinian (FA2) firing rate increases continuously until 200 Hz (is capable of recognising frequencies up to 500 Hz)
what does FA2s extremely low MM threshold mean
requires very little indentation to fire (lower than both superficial cells)
do ruffini endings work the same in all directions of stretch
no - best firing rate when they are stretched end to end (highly tuned to direction of stretch)
what allows pacinian corpuscles to be sensitive to vibration
concentric fluid filled laminae aorund a sensory nerve terminal that transmits vibration very well
- they are sensitve to alternating inputs (mechanical vibration - which is just repeated indentation)
how can the CNS determine the location of stimuli
based on which afferents specifically are active and the neuron’s receptive field
which receptor codes for spatial details (size and shape)
SA1 - merkel cells
how does a small vs large probe impact discharge rate
small probe = high discharge in a few afferents (higher pressure with same force due to smaller SA)
large probe = lower discharge rate in more afferents (larger SA)
would rough or slippery objects evoke a greater response in FA1 afferents
slippery = high afferent response because more grip force is required
rough = low afferent response because less grip force is needed
