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NROC64H3 Study Guide - Final Guide: Mechanoreceptor, Lamellar Corpuscle, Glabrousness

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Somatic sensory system
somatic sensation-allows our body to feel, ache, chill and know what its par t s are doing
-is sensitive to many kinds of stimuli; pressure, position, distension of baldder, temperature of brain and
limbs etc
when stimuli become strong, somatic sensation also responsible for offensive but imp feeling: pain
Somatic sensory systems is diff from other sensory system in 2 diff ways;
1)its receptors are distributed throughout the body vs beign concentrated in small, specialized locations
2) it responds to many diff kind sof stimuli, i.e a group of 4 senses rather one single sense- --touch> temp.
>pain and body position
somatic sensory is a collective category for all sensations that are not seeing, hearing, smelling, tasting
a single receptor can encode stimulus features such as intensity, duration, position and soemtimes
direction but a single stimulus activates many receptors---> the CNS interprets the activity of vast receptor
array and generates perceptions
sensation of touch begins at the skin
2 major types of skin; hairy and glabrous(=hairless)
skin's outer layer: epidermis
skin's inner layer; dermis
functions of skin:
--protective function
---prevents evaporation of body fluids into the environment
--provides direct contact withthe world
skin - largest sensory organ we have
-----is very sensitive
most of the sensory recpetors in skin are mechanoreceptors
are sensitive to physical distortion such as streching and bending:)
present thorugh out the body
they monitor contact with skin and pressure in the hear t and blood vessels, stretching of the digestive
organ and urinary bladder and force against teeth
contain unmyelianted axon branches, these axo n s have mechanosensitive ion channels:>gating depends
on stretching or changes in tension of surrounding membrane
Pacinian corpuscle :
lies deep in the dermis
largest receptor
can be seen with naked eye
Ruffini's endings: smaller than pacinian corpuscle
found in both hairy and glabrous skin
Meissner's corpuscle-are located on the ridges of glabrous skin i.e on the tip of finger tips
1/10 SIZE OF pacinian corpuscles
Merkel's disks-located with in the epidermis
consist of a nerve terminal and a flattened non neural epithelial cell
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