Lecture Human anatomy and physiology - Chapter 13: The peripheral nervous system and reflex activity (part a)

In this chapter, you will learn to: Define peripheral nervous system and list its components; classify general sensory receptors by structure, stimulus detected, and body location; outline the events that lead to sensation and perception; describe receptor and generator potentials and sensory adaptation; describe the main aspects of sensory perception.
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Lecture Human anatomy and physiology - Chapter 13: The peripheral nervous system and reflex activity (part a) PowerPoint® Lecture Slides prepared by Janice Meeking, Mount Royal College CHAPTER 13 The Peripheral Nervous System and Reflex Activity: Part ACopyright © 2010 Pearson Education, Inc. Peripheral Nervous System (PNS) • All neural structures outside the brain • Sensory receptors • Peripheral nerves and associated ganglia • Motor endingsCopyright © 2010 Pearson Education, Inc. Central nervous system (CNS) Peripheral nervous system (PNS) Sensory (afferent) Motor (efferent) division division Somatic nervous Autonomic nervous system system (ANS) Sympathetic Parasympathetic division divisionCopyright © 2010 Pearson Education, Inc. Figure 13.1 Sensory Receptors • Specialized to respond to changes in their environment (stimuli) • Activation results in graded potentials that trigger nerve impulses • Sensation (awareness of stimulus) and perception (interpretation of the meaning of the stimulus) occur in the brainCopyright © 2010 Pearson Education, Inc. Classification of Receptors • Based on: • Stimulus type • Location • Structural complexityCopyright © 2010 Pearson Education, Inc. Classification by Stimulus Type • 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 (e.g. extreme heat or cold, excessive pressure, inflammatory chemicals)Copyright © 2010 Pearson Education, Inc. Classification by Location 1. Exteroceptors • Respond to stimuli arising outside the body • Receptors in the skin for touch, pressure, pain, and temperature • Most special sense organsCopyright © 2010 Pearson Education, Inc. Classification by Location 2. Interoceptors (visceroceptors) • Respond to stimuli arising in internal viscera and blood vessels • Sensitive to chemical changes, tissue stretch, and temperature changesCopyright © 2010 Pearson Education, Inc. Classification by Location 3. Proprioceptors • Respond to stretch in skeletal muscles, tendons, joints, ligaments, and connective tissue coverings of bones and muscles • Inform the brain of one’s movementsCopyright © 2010 Pearson Education, Inc. Classification by Structural Complexity 1. Complex receptors (special sense organs) • Vision, hearing, equilibrium, smell, and taste (Chapter 15) 2. Simple receptors for general senses: • Tactile sensations (touch, pressure, stretch, vibration), temperature, pain, and muscle sense • Unencapsulated (free) or encapsulated dendritic endingsCopyright © 2010 Pearson Education, Inc. Unencapsulated Dendritic Endings • Thermoreceptors • Cold receptors (10–40ºC); in superficial dermis • Heat receptors (32–48ºC); in deeper dermisCopyright © 2010 Pearson Education, Inc. Unencapsulated Dendritic Endings • Nociceptors • Respond to: • Pinching • Chemicals from damaged tissue • Temperatures outside the range of thermoreceptors • CapsaicinCopyright © 2010 Pearson Education, Inc. Unencapsulated Dendritic Endings • Light touch receptors • Tactile (Merkel) discs • Hair follicle receptorsCopyright © 2010 Pearson Education, Inc.Copyright © 2010 Pearson Education, Inc. Table 13.1 Encapsulated Dendritic Endings • All are mechanoreceptors • Meissner’s (tactile) corpuscles—discriminative touch • Pacinian (lamellated) corpuscles—deep pressure and vibration • Ruffini endings—deep continuous pressure • Muscle spindles—muscle stretch • Golgi tendon o ...