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Essentials of Human Anatomy & Physiology Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Elaine N. Marieb Chapter 7 The Nervous System
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Functions of the Nervous System Slide 7.1a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Sensory input – gathering information To monitor changes occurring inside and outside the body Changes = stimuli Integration To process and interpret sensory input and decide if action is needed
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Functions of the Nervous System Slide 7.1b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Motor output A response to integrated stimuli The response activates muscles or glands
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Structural Classification of the Nervous System Slide 7.2 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Central nervous system (CNS) Brain Spinal cord Peripheral nervous system (PNS) Nerve outside the brain and spinal cord
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Functional Classification of the Peripheral Nervous System Slide 7.3a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Sensory (afferent) division Nerve fibers that carry information to the central nervous system Figure 7.1
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Functional Classification of the Peripheral Nervous System Slide 7.3b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Motor (efferent) division Nerve fibers that carry impulses away from the central nervous system Figure 7.1
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Functional Classification of the Peripheral Nervous System Slide 7.3c Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Motor (efferent) division Two subdivisions Somatic nervous system = voluntary Autonomic nervous system = involuntary Figure 7.1
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Organization of the Nervous System Slide 7.4 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 7.2
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Nervous Tissue: Support Cells (Neuroglia) Slide 7.5 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Astrocytes Abundant, star-shaped cells Brace neurons Form barrier between capillaries and neurons Control the chemical environment of the brain Figure 7.3a
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Nervous Tissue: Support Cells Slide 7.6 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Microglia Spider-like phagocytes Dispose of debris Ependymal cells Line cavities of the brain and spinal cord Circulate cerebrospinal fluid Figure 7.3b, c
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Nervous Tissue: Support Cells Slide 7.7a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Oligodendrocytes Produce myelin sheath around nerve fibers in the central nervous system Figure 7.3d
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Nervous Tissue: Support Cells Slide 7.7b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Satellite cells Protect neuron cell bodies Schwann cells Form myelin sheath in the peripheral nervous system Figure 7.3e
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Nervous Tissue: Neurons Slide 7.8 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Neurons = nerve cells Cells specialized to transmit messages Major regions of neurons Cell body – nucleus and metabolic center of the cell Processes – fibers that extend from the cell body
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Neuron Anatomy Slide 7.9a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Cell body Nissl substance – specialized rough endoplasmic reticulum Neurofibrils – intermediate cytoskeleton that maintains cell shape Figure 7.4a
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Nerve Fiber Coverings Slide 7.12 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Schwann cells – produce myelin sheaths in jelly-roll like fashion Nodes of Ranvier – gaps in myelin sheath along the axon Figure 7.5
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Neuron Cell Body Location Slide 7.13 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Most are found in the central nervous system Gray matter – cell bodies and unmylenated fibers Nuclei – clusters of cell bodies within the white matter of the central nervous system Ganglia – collections of cell bodies outside the central nervous system
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Functional Classification of Neurons Slide 7.14a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Sensory (afferent) neurons Carry impulses from the sensory receptors Cutaneous sense organs Proprioceptors – detect stretch or tension Motor (efferent) neurons Carry impulses from the central nervous system
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Functional Classification of Neurons Slide 7.14b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Interneurons (association neurons) Found in neural pathways in the central nervous system Connect sensory and motor neurons
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Neuron Classification Slide 7.15 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 7.6
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Structural Classification of Neurons Slide 7.16a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Multipolar neurons – many extensions from the cell body Figure 7.8a
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Structural Classification of Neurons Slide 7.16b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Bipolar neurons – one axon and one dendrite Figure 7.8b
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Structural Classification of Neurons Slide 7.16c Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Unipolar neurons – have a short single process leaving the cell body Figure 7.8c
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Fire your synapses Build a Neuron!
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1.Using the materials at hand build a motor neuron 2.Be sure to include: - dendrite cell body axon myelin sheath schwann cell nodes of Ranvier axon terminal synapse neurotransmitter 3.Include a description of the role each of the above structures plays in nerve cell function. 4.Surround your nerve cell with: astrocytes, microglial cells, and Oligodendrocytes. 5.Explain the supporting role these cells play in nerve tissue Build a Motor Neuron!
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Functional Properties of Neurons Slide 7.17 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Irritability – ability to respond to stimuli Conductivity – ability to transmit an impulse The plasma membrane at rest is polarized Fewer positive ions are inside the cell than outside the cell
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Starting a Nerve Impulse Slide 7.18 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Depolarization – a stimulus depolarizes the neuron’s membrane A deploarized membrane allows sodium (Na + ) to flow inside the membrane The exchange of ions initiates an action potential in the neuron Figure 7.9a–c
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Resting Membrane Potential
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Nerve Impulse Propagation Slide 7.20 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The impulse continues to move toward the cell body Impulses travel faster when fibers have a myelin sheath Figure 7.9c–e
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Action Potentials
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Continuation of the Nerve Impulse between Neurons Slide 7.21 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Impulses are able to cross the synapse to another nerve Neurotransmitter is released from a nerve’s axon terminal The dendrite of the next neuron has receptors that are stimulated by the neurotransmitter An action potential is started in the dendrite
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How Neurons Communicate at Synapses Slide 7.22 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 7.10
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Diagram pg 403 Talk through each event
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Synapse
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Source: Gray Transmission Across the Synapse
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Major Neurotransmitters in the Body NeurotransmitterRole in the Body Acetylcholine Dopamine GABA (gamma-aminobutyric acid) Glutamate Glycine Norepinephrine Serotonin NIH Publication No. 00-4871
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Put It all Together -Stimulus- temperature/pressure on skin light- sound- eyes and ears correct shape molecule taste buds /nose -Action Potential propagates along axon -Neurotransmitter released into synapse - New action potential begins in adjoining nerve or muscle cell
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