Chapter_12_Nervous_Tissue_update.ppt - Chapter 12 Nervous Tissue • Controls and integrates all body activities within limits that maintain life •

Chapter_12_Nervous_Tissue_update.ppt - Chapter 12 Nervous...

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12-1 Chapter 12 Nervous Tissue Controls and integrates all body activities within limits that maintain life Three basic functions (Sensory) sensing changes with sensory receptors fullness of stomach or sun on your face (Integrating) interpreting and remembering those changes (Motor) reacting to those changes with effectors muscular contractions glandular secretions
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12-2 Organization of the Nervous System CNS is brain and spinal cord PNS is everything else
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12-3 Subdivisions of the PNS Somatic (voluntary) nervous system (SNS) neurons from cutaneous and special sensory receptors to the CNS motor neurons to skeletal muscle tissue Autonomic (involuntary) nervous systems sensory neurons from visceral organs to CNS motor neurons to smooth & cardiac muscle and glands sympathetic division (speeds up heart rate) parasympathetic division (slow down heart rate) Enteric nervous system (ENS) involuntary sensory & motor neurons control GI tract neurons function independently of ANS & CNS
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12-4 Nucleus with Nucleolus Parts of a Neuron Axons or Dendrites Cell body Neuroglial cells
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12-5 Dendrites Conducts impulses towards the cell body Typically short, highly branched & unmyelinated Surfaces specialized for contact with other neurons
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12-6 Axons Conduct impulses away from cell body Long, thin cylindrical process of cell Arises at axon hillock Impulses arise from initial segment (trigger zone) Side branches (collaterals) end in fine processes called axon terminals Swollen tips called synaptic end bulbs contain vesicles filled with neurotransmitters Synaptic boutons
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12-7 Functional Classification of Neurons Sensory (afferent) neurons transport sensory information from skin, muscles, joints, sense organs & viscera to CNS Motor (efferent) neurons send motor nerve impulses to muscles & glands Interneurons (association) neurons connect sensory to motor neurons
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12-8 Structural Classification of Neurons Based on number of processes found on cell body multipolar = several dendrites & one axon most common cell type (All Motor Neurons are of this type) bipolar neurons = one main dendrite & one axon found in retina, inner ear & olfactory unipolar neurons = one process only are always sensory neurons
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12-9 Half of the volume of the CNS Smaller cells than neurons 4 cell types in CNS astrocytes, oligodendrocytes, microglia & ependymal 2 cell types in PNS schwann and satellite cells Neuroglial Cells
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12-10 Astrocytes Star-shaped cells Form blood-brain barrier by covering blood capillaries Metabolize neurotransmitters Regulate K+ balance Provide structural support
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12-11 Oligodendrocytes Most common glial cell type Each forms myelin sheath around more than one axons in CNS Analogous to Schwann cells of PNS
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12-12 Microglia Small cells found near blood vessels Phagocytic role -- clear away dead cells Derived from cells that also gave rise to macrophages & monocytes
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  • Spring '17
  • ballock

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