AP-Ch-8And11 - CHAPTER 11 ECKERT et al., 5th ed. Pg. 8- 1...

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CHAPTER 11 ECKERT et al., 5th ed. Pg. 8- 1 CHAPTERS 8 & 11. Structural and Functional Organization of the Nervous System EVOLUTION of NERVOUS SYSTEM (pg 280) Cannot be reconstructed from fossils because soft tissues are not preserved like bone, teeth, and some skins. Anatomically Simplest Nervous System: diffuse nerve net with little organization stimulation results in general, global response ex. jelly fish Ganglia Organization 1. worms and arthropods: bilateral symmetry and segmentally structured body segments are controlled by ganglia head ganglion is usually larger (accumulation of sensory neurons) 2. molluscs (snails) & echinoderms (ex. starfish) radial symmetry no clear head ganglion arthropods: include a. crustaceans (crabs and lobsters) b. arachnids (spiders, scorpions, ticks, and mites) c. insects (only invertebrates capable of flight, dominant organisms on this planet) SUMMARY: basic principles of evolution of the nervous system (pg 280): please read!!! 1
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CHAPTER 11 ECKERT et al., 5th ed. Pg. 8- 2 ORGANIZATION of the VERTEBRATE NERVOUS SYSTEM (pg 284) CENTRAL NERVOUS SYSTEM PERIPHERAL NERVOUS SYSTEM intrinsic neurons:     somata and processes all in CNS  extrinsic neurons:    somata in CNS, distal axon in PNS BRAIN SPINAL CORD               IN   sensory receptors  sensory neurons  (afferent)             OUT   motor neuron fibers  (efferent)                AUTONOMIC NS     SYMPATHETIC      PARASYMPATHETIC                                 ( body  viscera )    "fight or flight"          calms, reduces                   responses                   activity, but                                                         also stimulates                                                     digestion SOMATIC NS ORGANIZATION of SPINAL CORD Number of spinal nerves 8 cervical; 12 thoracic; 5 lumbar; 5 sacral, 1 coccygeal per side (31 per side) (see pg 285) Simple Spinal Reflex Arcs pg 286 simplest: receptor cell ---->>>>> effector cell (gland or muscle) Spinal Reflexes in vertebrates (brain is not required for their function): 1 2 3 4 5 receptor cell or structure >>> sensory neuron >>> interneuron >>> motor neuron >>> effector OR receptor structure >>> sensory neuron >>> motor neuron >>> effector the latter reflex arc (without an interneuron) is known only for for the stretch reflex! 2   (a) 1; (b) 5; (c) 6; (d) 8; (e) 9 59 Location of motor neurons  
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CHAPTER 11 ECKERT et al., 5th ed. Pg. 8- 3 1. fascilulus gracilis conscious touch sensations from lower body 2. fasciculus cuneatus conscious touch sensations from upper body both also carry proprioceptive information 3. dorsal root sensory signals into spinal cord 4. dorsal root ganglion contains all unipolar cells that form special receptor endings in periphery
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AP-Ch-8And11 - CHAPTER 11 ECKERT et al., 5th ed. Pg. 8- 1...

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