Somatosensory II Flashcards
Mastery
Mechanotransduction
process by which mechanical energy gets converted to voltage change in sensory neurons
mechanical stress opens up channels and Na+ rushes in, causing a voltage change in the cell.
needs enough of a stimulus
Receptive field
A cutaneous RECEPTIVE FIELD is the region of the
skin that is capable of evoking action potentials in a
given cutaneous afferent
receptive field is all the cells in a given area
Anatomy of Cutaneous receptors
number of types and where are they
how are they classified
What are the two types
4 types in non hairy glabrous skin
hands and feet
based on receptive field size and how they respond to indentation of the skin
Type 1-superficial- Meissner and Merkel
Type 2- Ruffini and Pacinian
4 types of receptors
and what kind of receptor they are(SA or FA) and what they measure
MMRP
Merkel(SA1) - curves and edges
Meissner(FA1) - slip and grip control, velocity
Ruffini(SA2) - skin stretch,
Pacinian(FA2) - acceleration and vibration
Merkel Cell
what type
superficial or depp
what is it sensitive too
GRAPH
Slow adapting Type 1. FA1
Superficial
Merkel like erkel is stupid
irregular discharge
sensitive to edges and curves
low threshold
SA so fires action potential how time stimulated
Meissner
what type
superficial or depp
what is it sensitive too. - frequency
GRAPH
Fast adapting Type 1. SA2
superficial
you miss meissner so hes fast but dumb
velocity across the skin and motion
sensitive to low frequency 30-50Hz
low threshold
Ruffini
what type
superficial or depp
what is it sensitive too
threshold???
are they found in other animals?
GRAPH
Slow adapting Type 2 SA2
deep
Ruffini is rough so takes a lot to get him going and he’s slow and deep. Dont stretch him very fat
regular discharge
sensitive to STRETCH
very high threshold
only in humans
Pacinian
what type
superficial or depp
what is it sensitive too
FREQUENCY???
GRAPH
Fast adapting type 2. - - - -FA2
deep
Pacinian is a philosipher, so his mind mind works fast, hes deep, and moves at high speeds and frequencies
Sensitive to acceleration
high frequencies of 40-500Hz
lowest threshold
what does it mean to be fast adapting or slow
Slow adapting- Merkel and Ruffini, fire action potential whole time they are stimulated
fast adapting- Pacinian and Meissner, only measure CHANGE and fire action potentials when changed
order of sensitivity
PMMR
Most
P
M( alphabetical
M( alphabetical
R
Least
Pacinian
Meissner
Merkel
Ruffini
Innervation density of 4 types, where are they spread out and dense
type 1 compared to type 2
receptor field size
hot spot
and how many cells are connected to one axon
tip of finger is type 1- merkel and meissner, high density
Type 2 evenly spread thru out the hand
Type 1:
high innervation rate, many cells for one axon
smaller receptor field
many hot spots of high sensitivity
Type 2:
one cell for one axon
large receptor field size
one large hot spot
vibration sensitivity
two types
perceptual and neural threshold
perception
amt of indent needed to fire an action potential and for us to perceive it
Neural:
amt of indent needed for cutaneous receptors to respond to vibrations and each frequency
Pacinian, Meissner, Merkel, Ruffini
