Peripheral Somatosensory Mechanism Flashcards
What is the primary function of skin ridges?
provide grip (they also have receptors embedded within)
Mechanoreceptors tend to densely occupy what kind of skin?
glabrous skin
What are the four types of mechanoreceptors? What kind of information do they provide to the brain?
Meissner corpuscles + Merkel complexes close to the surface Ruffini organs and Pacinian corpuscles deeper in the skin conscious sense of touch
T/F Mechanoreceptors have the fastest conducting axons
false, muscle proprioceptors have faster conduction
Where are meissner and merkel receptors found?
at the dermal ridges close to the surface
Where can we find Ruffini corpuscle?
embedded in the connective tissue
Where can we find Pacinian corpuscle
in the dermis, very close to subcutaneous layer
Mechanorecpetors detect _________ and use receptors that have __________ nerve endings. They can detect up ________ and also _________ of force.
distortion of the skin encapsulated magnitude frequency
How does physical distortion get transduced to neural signal
The proteins are tethered to each other, so physically force can pull open a series of Na channels to create action potential.
What is the difference between slow and rapid adaptation
slowly adapting receptors encode the stimulus over a long time frame, whereas rapidly adapting receptors give the initial impulse upon activation
What is the difference between receptors for tactile information and pain?
the range of response and the threshold of activation for somatosensation are smaller
Which receptors are slowly adapting?
Merkel and Ruffini
Which receptors are rapidly adapting?
Meissner and Pacinian
In terms of receptor number, deeper receptors tend to be __________
less dense
Which mechanoreceptor is most numerous
Meissner
What do the four types of receptors primarily detect?
Meissner - transient response to skin movement Merkel - edge or indentation Ruffini - stretch and direction of stretch. Proprioceptive Pacinian - vibration
When picking up an object, what do the four receptors encode individually
Meissner - rate of force (change in surface contact) Merkel - grip force Pacinian - vibration Riffini - hand posture
What is a receptive field?
how much territory a single fibre respond to
Receptive fields often ________ , and where the receptive fields are dense, there is higher __________ . On our upper limb, there are denser receptive fields on the ________, and less dense in other parts
overlap
spatial resolution
fingertip
What is the difference between the signal transmission of nociceptor and mechanosensory receptor?
nociceptors make their first synapse in the spinal cord
Why do deeper receptors have larger receptive fields?
Because force radiates over longer distance, and deeper receptors can respond to singals that are off target
