Somatic Sensory System Flashcards
name the differences between somatic senses and other senses
- receptors are distributed throughout the body as opposed to being concentrated at small, specialized locations
- responds to many kinds of stimuli
- at least four senses
name the four senses
temperature
body position
touch
pain
name the 5 types of somatic receptors
mechanoreceptors nociceptors thermoreceptors proprioceptors chemoreceptors
define mechanoreceptors
sensitive to physical distortion
define nociceptors
respond to damaging stimuli; pain
define thermoreceptors
sensitive to changes in temperature
define proprioceptors
monitor body position
are associated with joints, tendons
define chemoreceptors
respond to certain chemicals
smell, taste
nociceptors and thermoreceptors can be classified as
free nerve endings
the most cutaneous receptors are
encapsulated
what does stimuli applied on skin do?
it deforms or changes a receptor
what does this deformity do?
alters the ionic permeability of the receptor creating generator potentials
define sensation?
is the process initiated by stimuli acting on sensory receptors
how can mechanical energy be differentiated?
stimulus frequency
stimulus pressure
receptive field
name the types of mechanoreceptors
pacinian meissner's corpuscle ruffini merkel's disk hair follicle receptor
the pacinian corpuscle are…
sensitive to vibration
where is the pacinian corpuscle located?
between the dermal and hypodermal
subcutaneous tissue
T/F:the pacinian corpuscle can be associated with joints
True
Meissner’s corpuscle are located in
dermal papillae
Meissner’s corpuscle are sensitive to what?
vibrations
Where are Ruffini’s located?
in the dermis of the skin
primarily the fingers
what doe Merkel’s disks tell?
light pressure and tactile discrimination
superficial pressure
where are Merkel’s disks located?
in basal layer of epidermis
Hair follicle receptors respond to
very slight bending of the hair and are involved in light touch
Nociceptors are what kind of nerve endings?
free, unmyelinated nerve endings
what do nociceptors tell you?
signal that body tissue is being damaged
where can nociceptors be found?
in most tissues but not the brain
what are the 3 types of damage detected?
mechanical
thermal
chemical
mechanical refers to
strong pressure (sharp objects)
thermal refers to
active when tissues begin to be destroyed
chemical refers to
environmental agents or those from tissues itself
thermoreceptors tightly regulates _______
the brain
at what temperature?
37C
brain function changes…
above and below that temperature
____________in our skin that can perceive changes in temperature as small as 0.01 C
Specialized receptors
warm begin firing at
30C up to 45C
cold begin firing at
35C to 10C
which receptors are more numerous in any given area of skin.
cold receptors
proprioceptors are involved with
body position
describe what it is looking at regarding body position
where the body is
direction of movement
speed of movement
where can these proprioceptors be found?
in the skeletal muscles
name the 2 kinds of mechanosensitive proprioceptors
muscle spindles
golgi tendon organs
the muscle spindles consist of
specialized intrafusal muscle fibers distributed among ordinary muscle fibers
detect changes in muscle length
the golgi tendon organs are distributed…
among collagen fibers in tendons and detects changes in muscle tension
how many spinal segments are there?
30
what do they consist of?
paired dorsal and ventral roots
spinal segments are divided into 4 groups:
cervical, thoracic, lumbar, sacral
cervical:
C1-C8
thoracic:
T1-T12
lumbar:
L1-L5
sacral:
S1-S5
cervical controls mainly
head,shoulders,neck, and fingers
thoracic controls mainly
chest and back
lumbar mainly controls
umbilical and down
front of legs
sacral mainly controls
back of leg
____ and ______ are related
segmented organization of the spinal nerve
sensory innervation of skin
define dermatome
area of skin innervated by the dorsal roots of a single spinal segment
where can you find cervical dermatomes?
above sternum
where can you find thoracic dermatomes?
top of sternum to waist
where are lumbar dermatomes?
front of legs and stomach
where can sacral dermatomes?
back of legs and genitals
name the 2 basic systems of somatic sensory pathwayd
- pain and temperature
2. touch and proprioception
which pathway is for touch and proprioception
Dorsal column-medial lemniscal pathway
which pathway is for pain and temperature
Spinothalamic pathway
In the DCML pathway information ascends…
through the dorsal column on the ipsilateral side of the spinal cord
where is the synapse?
in the medulla
then the signal crosses
over and ascends via the medial lemniscus to the thalamus
then where does it synapse?
in VP thalamus
where does it project to
the cortex
in the ST pathway, information crosses to the…
contralateral side in the spinal cord
then it ascends via what?
spinothalamic tract
it later synapses at
the thalamus (VP)
it later projects to the
cortex
Information carried in each pathway remains…
separate
up to how?
to the cortex
the ventral posterior (VP) or thalamus nucleus receives…
the information and projects to the somatosensory cortex
if you injure the spinal pathway of one side, you will lose…
pain and temperature of opposite side
_____________________ receives simple segregated streams of sensory information
primary somatosensory cortex
where does the integration take place?
in the posterior parietal cortex
define hyperalgesia
tissue already damaged is much more sensitive to pain
how are nociceptors sensitized?
by various substances released by damaged tissue
how can pain be modified?
by non-painful sensory input
and endorphins
define somatotopy
mapping of the body’s surface sensations onto a brain structure
how is the size of the area related?
to the importance of the sensory input (finger tip versus elbow)
