Somatosensory processing part 1

Sensory systems chapter 9

Sensory neuron?

Oxygen sensory neuron

transduction

convert information into neural signals

transmission

pass information on

inference

did something just happen?

4 qualities of information to encode

modality, intensity, duration, locatio4

5 factors that influence success or failure

fatigue, adaptation, sensitization, overlap/redundancy, damage/overload

All sensory fibers transmit nerve impulses in the form of

action potentials

activation of a sensory receptor causes a change in membrane potential called a

receptor potential

Sensory neuron?

taste

Sensory neuron?

smell

Sensory neuron?

Somatosensory

Sensory neuron?

muscle

Sensory neuron?

hearing

Sensory neuron?

vision

dorsal root ganglia are what kind of cells?

pseudo unipolar cellsnliu

An AP in a dorsal root ganglion may initiate

in the distal process in the periphery

An AP in a dorsal root ganglion may bypass

the cell body

An AP in a dorsal root ganglion may propagate

along the axon until reaching the synaptic terminal in the dorsal horn of the spinal cord

The distal section of the axon may either be a

bare nerve ending or encapsulated by a receptor structure od

dorsal root ganglia contain the

sensory neurons of the somatosensory system

sensory axons are classified according to their

diameter

the diameter of sensory axons governs their

myelination and conduction velocity

A alpha and A beta have what properties?

Myelinated, large diameter, muscle spindle proprioception, discriminative light touch

A delta properties

lightly myelinated, medium diameter, harmless temperature, itch, pain C

C fibers have what properties?

unmyelinated, small diameter, harmless temperature, itch, pain

sensory afferents differ in the size of their respective fields and reflect how

nerve endings branch

Ruffini ending

deep tension; slowly adapting

Meissner corpuscle

light touch; rapidly adapting

Merkel cells + afferents

sustained pressure; slowly adapting

Activation of mechxnosensitive nerve endings of the DRG transduces..

mechanical stimuli into AP to mediate the sense of touch

Sensory afferents differ in their responses to

sustained stimulation (degree of adaptation)

Slowly adapting afferents convey information about

spatial attributes such as size and shape

Rapidly adapting afferents convey information about

changes in ongoing stimulation (dynamic)

Dynamic adaptation change is encoded in

discrete bursts of AP

Pacinian corpuscle properties

vibration; large vague borders; fast adapting

Meissner’s corpuscle properties

touch; small sharp borders; fast adapting

Merkel’s discs properties

touch; small sharp borders; slow-adapting

Ruffini’s ending properties

stretch; large vague borders; slow-adapting

Deformation of the DRG by a mechanical stimulus does what

lowers the threshold needed to evoke an action potential

High threshold channels characterize

nociceptors (pain)

nociceptors are found predominantly in ___ and are activated by___

smaller DRG; higher pressures

Sensory neurons enter the spinal cord through the

dorsal roots

Each Dorsal root innervates a field of skin called

dermatome

Dermatomes are used to determine level of

lesion of spinal cord

Epidural blocks sensation through

several dermatomes