1. PowerPoint ® Lecture Slides prepared by Leslie Hendon, University of Alabama, Birmingham HUMAN ANATOMY fifth edition MARIEB | MALLATT | WILHELM 14 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Peripheral Nervous System PART 1

2. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Peripheral Nervous System  Nervous structures outside the brain and spinal cord  Nerves allow the CNS to receive information and take action  Functional components of the PNS  Sensory inputs and motor outputs  Categorized as somatic or visceral  Sensory inputs also classified as general or special

3. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Peripheral Nervous System  Autonomic nervous system (ANS)  General visceral motor part of the PNS  ANS has two divisions  Parasympathetic  Sympathetic

4. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Functional Organization of the PNS Figure 14.1

5. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Basic Structural Components of the PNS  Sensory receptors – pick up stimuli from inside or outside the body  Motor endings – axon terminals of motor neurons  Innervate effectors (muscle fibers and glands)  Nerves and ganglia  Nerves – bundles of peripheral axons  Ganglia – clusters of peripheral neuronal cell bodies

6. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Basic Anatomical Scheme of the PNS in the Region of a Spinal Nerve Figure 14.2

7. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Peripheral Sensory Receptors  Structures that pick up sensory stimuli  Initiate signals in sensory axons

8. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Peripheral Sensory Receptors  Two main categories of sensory receptors  Free nerve endings of sensory neurons  Monitor general sensory information  Complete receptor cells – specialized epithelial cells or small neurons  Monitor most types of special sensory information

9. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Peripheral Sensory Receptors  Wednesday  Sensory receptors also classified according to  Location  Type of stimulus detected  Structure

10. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Classification by Location  Exteroceptors – sensitive to stimuli arising from outside the body  Located at or near body surfaces  Include receptors for touch, pressure, pain, and temperature

11. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Classification by Location  Interoceptors – (visceroceptors) receive stimuli from internal viscera  Monitor a variety of stimuli  Proprioceptors – monitor degree of stretch  Located in musculoskeletal organs

12. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Classification by Stimulus Detected  Mechanoreceptors – respond to mechanical forces  Thermoreceptors – respond to temperature changes

13. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Classification by Stimulus Detected  Chemoreceptors  Respond to chemicals in solution  Photoreceptors – respond to light  Located in the eye  Nociceptors  Respond to harmful stimuli that result in pain

14. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Classification by Structure  General sensory receptors  Widely distributed  Nerve endings of sensory neurons monitor  Touch  Pressure  Vibration  Stretch  Pain  Temperature  Proprioception

15. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Classification by Structure  General sensory receptors are  Divided into two groups  Free nerve endings  Encapsulated nerve endings

16. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Free Nerve Endings  Abundant in epithelia and underlying connective tissue  Respond to pain and temperature  Monitor affective senses

17. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Free Nerve Endings  Two specialized types of free nerve endings  Merkel discs – lie in the epidermis  Slowly adapting receptors for light touch  Hair follicle receptors – wrap around hair follicles  Rapidly adapting receptors

18. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Unencapsulated Nerve Endings Table 14.1 (1 of 4)

19. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Encapsulated Nerve Endings  Consist of one or more end fibers of sensory neurons  Enclosed in connective tissue  Mechanoreceptors  Include four main types

20. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Encapsulated Nerve Endings  Meissner’s corpuscles  Spiraling nerve ending surrounded by Schwann cells  Occur in the dermal papillae  Rapidly adapting receptors for discriminative touch  Occur in sensitive, hairless areas of the skin

21. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Meissner’s Corpuscles Table 14.1 (2 of 4)

22. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Encapsulated Nerve Endings  Pacinian corpuscles  Single nerve ending surrounded by layers of flattened Schwann cells  Occur in the hypodermis  Sensitive to deep pressure – rapidly adapting receptors

23. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Encapsulated Nerve Endings  Ruffini’s corpuscles  Located in the dermis and respond to pressure  Monitor continuous pressure on the skin – adapt slowly

24. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Pacinian Corpuscles and Ruffini’s Corpuscles Table 14.1 (3 of 4)

25. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Encapsulated Nerve Endings  Proprioceptors  Monitor stretch in locomotory organs  Three types of proprioceptors

26. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Three Types of Proprioceptors  Muscle spindles – measure the changing length of a muscle  Imbedded in the perimysium between muscle fascicles  Golgi tendon organs – located near the muscle- tendon junction  Monitor tension within tendons  Joint kinesthetic receptors  Sensory nerve endings within the joint capsules

27. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Proprioceptors Table 14.1 (4 of 4)

28. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Structure of Proprioceptors Figure 14.4