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Chapter 13-The PNS and reflex activity
The Peripheral Nervous system (PNS) is made up of what?
Sensory and somatic neurons that arise from the spinal cpord to service regions of the body and the senory receptors.
Are cells that are specialized to respond to changes (Stimuli) in their environment to typically produce graded potentials in efferent nerve fibers
Is awareness (CNS) of stimulus
is the interpretation (CNS) of the meaning of the stimulus
What are the Classifications by Stimulus Type?
Respond to mechanical force like touch and pressure
Respond to changes in temperature
Responds to changes in light energy
Responds to the change in concentration of a chemical
If to much of something like Na+ it tells body to flush it out
Responds to pian
Substances P- can realease Dopamine (ex. cutters, excessive tattoos)
What are the Classifications by Location?
Respones to stimuli a rising from outside the body
Responds to stimuli occuring from within the body; Visceral
Responds to changes in limb position;
Lies within the skeletal muscles, joints and ligaments and Connective Tissue of bone and muscle
What are the Classifications by Structural Complexity?
Modified dendritic endings of sensory Neurons that monitor general sensory info
In skin- Merkel Disks
Sense organs that are localized collections of cells associated with Vision (eyes), Hearing (ears), Equilibrium, Smell (Olfaction), Taste (Gustatory)
(touch, pressure, stretch, vibration) temperature and monitoring and nocioreceptors
Unencapsulated Dendritic Endings
Merkel Disks in the skin, hair follicle receptors
Free (naked) nerve endings
Most abundant in the epithelia and CT that ate unmyelinated
Small- diameter, C-Fibers
Encapsulated Dendritic Endings
One or more fiber terminals of sensory neurons enclosed in a CT capsule and are normally mechanoreceptors
The Somatosensory System serves the body.......
Wall and limbs
input from exteroceptors, proptioceptors, & Interoceptors
input to CNS for interpretation
which makes a choice on how to proceed
Efferent signals to efferent cells which respond
What happens when processing at the Receptor Level?
Sensory receptors send info. about the stimulus (strength, duration, pattern) in the frequency of nerve impulses
A change in sensitivity at the sensory receptor in the presence of a constant stimulus
Harder and harder to get an Action Potential to occur
What happens when processing at the Circuit Level?
Delivers impulses to the appropriate levels of the Cerebral Cortex for localization and perception using a circuit of neurons (1st order, 2nd order, ect.)
What happens when processing at the Perceptual Level?
Interpretation of sensory input occuring within the cerebral cortex
What are the main aspects of sensory perception?
detecting that a stimulus had occurred
How intense the stimulus occurred
Location of stimulus
Texture interpretation and complex sensation
Varieties of stimulus
(Bitter and sweet of taste)
The ability to recognize a familiar pattern (environment)
Are activated by extremes of pressure and temperature and by the release of chemicals (histamine, K+, ATP,acids, Bradykinins) from injured cells
& burning pain fibers,
use glutamate and substance P as neurotransmitters in the 1st order neurons