touch

1. touch Smital Patel Alexa Paganini Nathan Penn Period 3

2. Touch sensory structures • Free Nerve Endings: free ends extend between epithelial cells; associated with sensations of touch and pressure • Meissner’s Corpuscles: small, flattened masses of connective tissue cells; respond to the motion of objects that barely contact the skin by interpreting impulses • Pacinian Corpuscles: large structures composed of connective tissue fibers and cells; respond to heavy pressure

3. Touch sensory structures

4. Types of receptors

5. Pathway of sensory information • Receptors are distributed throughout the skin and internal tissues, except for that of the brain. • When stimulated, receptors send impulses to the central nervous system. • These impulses are processed in the gray matter of the spinal cord before they ascend to the brain. • Within the brain, impulses pass through the reticular formation before being conducted to the cerebral cortex. • The cerebral cortex then interprets the source of the impulses and determines how to react.

6. Diagram of pathway

8. Disorders • Giaccai type acroosteolysis AKA Hereditary Sensory Neuropathy, Type 2 (HSN2): • Rare genetic disorder that usually begins in childhood. • Loss of feeling, especially in the hands and feet. • Loss of sensation often leads to neglect of wounds. • Could result in amputation in extreme cases.

9. Disorders • Tactile Agnosia: • Subtle and nondisabling disorder. • Results from lesions, tumors, or damage to the mesial temporal, relosplenial, or mesial occipital cortices of the brain. • Causes an individual to be unable to recognize objects by touch. • However, other senses can be used to identify objects without difficulty.