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

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

  1. PowerPoint® Lecture Slides prepared by Janice Meeking, Mount Royal College CHAPTER 13 The Peripheral Nervous System and Reflex Activity: Part A Copyright © 2010 Pearson Education, Inc.
  2. Peripheral Nervous System (PNS) • All neural structures outside the brain • Sensory receptors • Peripheral nerves and associated ganglia • Motor endings Copyright © 2010 Pearson Education, Inc.
  3. Central nervous system (CNS) Peripheral nervous system (PNS) Sensory (afferent) Motor (efferent) division division Somatic nervous Autonomic nervous system system (ANS) Sympathetic Parasympathetic division division Copyright © 2010 Pearson Education, Inc. Figure 13.1
  4. 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 brain Copyright © 2010 Pearson Education, Inc.
  5. Classification of Receptors • Based on: • Stimulus type • Location • Structural complexity Copyright © 2010 Pearson Education, Inc.
  6. 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.
  7. 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 organs Copyright © 2010 Pearson Education, Inc.
  8. Classification by Location 2. Interoceptors (visceroceptors) • Respond to stimuli arising in internal viscera and blood vessels • Sensitive to chemical changes, tissue stretch, and temperature changes Copyright © 2010 Pearson Education, Inc.
  9. 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 movements Copyright © 2010 Pearson Education, Inc.
  10. 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 endings Copyright © 2010 Pearson Education, Inc.
  11. Unencapsulated Dendritic Endings • Thermoreceptors • Cold receptors (10–40ºC); in superficial dermis • Heat receptors (32–48ºC); in deeper dermis Copyright © 2010 Pearson Education, Inc.
  12. Unencapsulated Dendritic Endings • Nociceptors • Respond to: • Pinching • Chemicals from damaged tissue • Temperatures outside the range of thermoreceptors • Capsaicin Copyright © 2010 Pearson Education, Inc.
  13. Unencapsulated Dendritic Endings • Light touch receptors • Tactile (Merkel) discs • Hair follicle receptors Copyright © 2010 Pearson Education, Inc.
  14. Copyright © 2010 Pearson Education, Inc. Table 13.1
  15. 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 organs—stretch in tendons • Joint kinesthetic receptors—stretch in articular capsules Copyright © 2010 Pearson Education, Inc.
  16. Copyright © 2010 Pearson Education, Inc. Table 13.1
  17. From Sensation to Perception • Survival depends upon sensation and perception • Sensation: the awareness of changes in the internal and external environment • Perception: the conscious interpretation of those stimuli Copyright © 2010 Pearson Education, Inc.
  18. Sensory Integration • Input comes from exteroceptors, proprioceptors, and interoceptors • Input is relayed toward the head, but is processed along the way Copyright © 2010 Pearson Education, Inc.
  19. Sensory Integration • Levels of neural integration in sensory systems: 1. Receptor level—the sensor receptors 2. Circuit level—ascending pathways 3. Perceptual level—neuronal circuits in the cerebral cortex Copyright © 2010 Pearson Education, Inc.
  20. 3 Perceptual level (processing in cortical sensory centers) Motor cortex Somatosensory cortex Thalamus Reticular formation Pons Cerebellum 2 Circuit level Medulla (processing in Spinal ascending pathways) cord Free nerve endings (pain, cold, warmth) Muscle spindle 1 Receptor level (sensory reception Joint and transmission kinesthetic to CNS) receptor Copyright © 2010 Pearson Education, Inc. Figure 13.2
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