Unit 3: somatic Flashcards
perception
interpretation of sensation into meaningful forms occurs in the cerebrum
how much sensory information is consciously perceived
very little, most is not processed at all
somatic sensation
sensory information from skin and musculoskeletal
information from skin examples
superficial: touch, pain, temperature, pressure and vibration; also deep cutateous
information from musculoskeletal
proprioception, tension on muscles, joints, position, deep vibration and pain
differences in system
unevenly distribution of receptors, responsiveness, different diameters of nerves
types of receptors
mechanoreceptors, chemoreceptors, thermoreceptors
mechanoreceptors
mechanical deformations touch, pressure, stretch, vibration
chemoreceptors
released by cells, injury or infection
thermoreceptors
hot, cold
parts of body loaded with receptors
hands and face
differences in architecture
encapsulated or uncapsulated
unencapsulated
free nerve endings, primarily sensitive to tissue damage: pain receptors, temperature fluxes
encapsulated sensory cells
touch, vibration
Differences in receptors
architecture, receptive fields, type of innervation, attenuation properties
pacinian corpuscles
deep vibration
ruffinis endings
deep, stretch, joint deformation, warmth, how much force is put on joint
meissners corpuscles
shallow, light touch vibration
Merkel’s disks
shallow, light touch
krause end bulbs
shallow, cold
nerve endings
temperature
Some nerve endings respond to
touch, tickle, or itch
What has small receptive fields
meissners and merkel
what has large receptive fields
pacinian and ruffini
test for receptive field
two point test, whether two points can be distinguished; high resolution vs low resolution
2 types of fine touch
superficial and subcutaneous
coarse touch
uses free nerve ending, pleasant touch tickle, itch
what uses meissners and merkles touch
superficial fine touch
types of innervation
Large myelinated, medium myelinated, small myelinated and small unmyelinated
4 types of axons
Aa, AB, Ad, C
what do C fibers do
mediate pain and temperature
what is largest fiber
Aa, tell your brain where your muscles are
Where are largest and fastest
in muscles not skin
Receptor attenuation refers to
Adaptation
pt suffers 3rd degree bone, not through hyperdermis what will they be able to detect
not touch or temperature, but deep vibration perhabs
tonic
slow to adapt, keep firing as long as stimulus is present provide long term feedback (carotid sinus*)
phasic
respond only when there is a change in the stimulus
3 parts of muscle spindles
Muscle fibers, sensory neurons, motor neurons
golgi tendon organs
determine how much tension a muscle is under, only sensitive to force, can send inhibitory signals to the muscle to relax if under too much force
joint receptors
Respond to movement of joint and ligaments: ruffini, paciniform, ligament receptors, free nerve ending; fastest
tonic
slow to adapt, keep firing as long as stimulus is present provide long term feedback (carotid sinus)
Type of proprioceptors
Muscle spindles, golgi tendon organ, joint receptors
there is redundency in?
proprioceptors so if you lose one you have more
golgi tendon organs
determine how much tension a muscle is under, only sensitive to force
dorsal columns carry
discriminate touch and proprioception
primary relay
carries from receptor to medulla
secondary relay carries
crosses over and ascends to ventral posteriolateral nucleus, medulla to thalamus
tertiary relay carries
conveys info from thalamus to the cerebral cortex
joint receptors nerves
ruffini, paciniform, ligament receptors, free nerve; fastest
primary sensory cortex discriminates among
size, texture, shape
somatosensory association areas
determines what thing is from sensory info
3 pathways that carry info to brain
conscious relay, divergent pathways, and unconscious relay
who do paths differ
in ability to locate stimulus, and awareness
stereognosis
ability to identify something by touch only
nerve bundlig
tend to stay together from same part of body, usually minimum of 3 neurons
conscious relay
high fidelity info, info is also discriminative, can make fine distinctions
2 pathways of conscious relay
dorsal columns and anteriolateral tracts
injure right side of cord at L1, where will pain be
won’t feel it on the left side, won’t feel proprioception on right side
will sensory be ipsilateral or contralateral of injury
if injury is distal end of cord it will be ipsilateral, if at brain stem it will be contralateral
primary sensory cortex
discriminates size, texture, shape
association
determines what thing is from sensory info
how do touch and proprioception rise?
ipsilaterally before crossing over to medulla
what happens if you lose peripheral afferent info
awareness of body can be lost
stereonosis
can identify by feeling
if have lesion loss will occur
below the lesion
course, pain and touch travel through
lateral tracts
spinothalamic path
temperature pathway, cross over is immediate
High fidelity
can feel precisely where stimulus is
What is a receptive field
how large an area of the skin that is served by a single receptor and neuron
What type of touch is Pacinian and ruffini’s
subcutaneous fine touch
What primary afferent axon mediates touch sensation
AB
Tonic receptor example
Merkel’s disk, Ruffini’s ending
Phasic receptor example
Meissner’s corpuscle, pacinian corpuscle
Muscle spindles are
the sensory organs embedded muscle that keep muscles from lengthening too much or too fast
Conscious relay is
awareness of stimuli and precise location
Divergent pathways are
awareness but cannot localize
Unconscious relays are
unaware
Anteriolateral tracts carry what kind of information
pain, temperature and coarse touch
Muscle spindle function
Keeps muscles from lengthening too much or too fast, informs CNS of joint angles
Anterolateral tract
pain, temperature, coarse touch
