Chapter 13 Part 1 PNS

Chapter 13 Part 1 PNS - The Peripheral Nervous System(PNS...

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Unformatted text preview: The Peripheral Nervous System (PNS) Part 1 Angela Peterson-Ford, PhD [email protected] Chapter 13 The Peripheral Nervous System (PNS) Part 1 PNS – all neural structures outside the brain and spinal cord Includes sensory receptors, peripheral nerves, associated ganglia, and motor endings Provides links to and from the external environment Peripheral Nervous System (PNS) PNS in the Nervous System Figure 13.1 Structures specialized to respond to stimuli Activation of sensory receptors results in depolarizations that trigger impulses to the CNS The realization of these stimuli, sensation and perception, occur in the brain Sensory Receptors Mechanoreceptors – respond to touch, pressure, vibration, stretch, and itch Thermoreceptors – sensitive to changes in temperature Photoreceptors – respond to light energy (e.g., retina) Chemoreceptors – respond to chemicals (e.g., smell, taste, changes in blood chemistry) Nociceptors – sensitive to pain-causing stimuli Receptor Classification by Stimulus Type Respond to stimuli arising outside the body Found near the body surface Sensitive to touch, pressure, pain, and temperature Include the special sense organs Receptor Class by Location: Exteroceptors Respond to stimuli arising within the body Found in internal viscera and blood vessels Sensitive to chemical changes, stretch, and temperature changes Receptor Class by Location: Interoceptors Respond to degree of stretch of the organs they occupy Found in skeletal muscles, tendons, joints, ligaments, and connective tissue coverings of bones and muscles Constantly “advise” the brain of one’s movements Receptor Class by Location: Proprioceptors Receptors are structurally classified as either simple or complex Most receptors are simple and include encapsulated and unencapsulated varieties Complex receptors are special sense organs Receptor Classification by Structural Complexity Free dendritic nerve endings ◦ Respond chiefly to temperature and pain Merkel (tactile) discs Hair follicle receptors Simple Receptors: Unencapsulated Meissner’s corpuscles (tactile corpuscles) Pacinian corpuscles (lamellated corpuscles) Muscle spindles, Golgi tendon organs, and Ruffini’s corpuscles Joint kinesthetic receptors Simple Receptors: Encapsulated Simple Receptors: Unencapsulated Table 13.1.1 Simple Receptors: Encapsulated Table 13.1.2 Simple Receptors: Encapsulated Table 13.1.3 Simple Receptors: Encapsulated Table 13.1.4 Survival depends upon sensation and perception Sensation is the awareness of changes in the...
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This note was uploaded on 01/06/2012 for the course BIOL 2401 taught by Professor Elainefanin during the Spring '11 term at Collins.

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Chapter 13 Part 1 PNS - The Peripheral Nervous System(PNS...

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