Somatosensory II

Question 1

Mechanotransduction

Answer 1

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

Question 2

Receptive field

Answer 2

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

Question 3

Anatomy of Cutaneous receptors
number of types and where are they
how are they classified

What are the two types

Answer 3

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

Question 4

4 types of receptors

and what kind of receptor they are(SA or FA) and what they measure

Answer 4

MMRP

Merkel(SA1) - curves and edges
Meissner(FA1) - slip and grip control, velocity
Ruffini(SA2) - skin stretch,
Pacinian(FA2) - acceleration and vibration

Question 5

Merkel Cell
what type
superficial or depp
what is it sensitive too
GRAPH

Answer 5

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

Question 6

Meissner
what type
superficial or depp
what is it sensitive too. - frequency
GRAPH

Answer 6

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

Question 7

Ruffini
what type
superficial or depp
what is it sensitive too
threshold???
are they found in other animals?
GRAPH

Answer 7

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

Question 8

Pacinian
what type
superficial or depp
what is it sensitive too
FREQUENCY???
GRAPH

Answer 8

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

Question 9

what does it mean to be fast adapting or slow

Answer 9

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

Question 10

order of sensitivity

Answer 10

PMMR
Most
P
M( alphabetical
M( alphabetical
R
Least

Pacinian
Meissner
Merkel
Ruffini

Question 11

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

Answer 11

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

Question 12

vibration sensitivity

two types

Answer 12

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