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Nervous System

Nervous System. Neural Tissue. Nervous System. Gathers sensory input Processes the input – INTEGRATION Dictates response – MOTOR OUTPUT. Divisions of the Nervous System. Peripheral Nervous System. AFFERENT division – INPUT from sensory receptors to the brain

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Nervous System

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  1. Nervous System Neural Tissue

  2. Nervous System • Gathers sensory input • Processes the input – INTEGRATION • Dictates response – MOTOR OUTPUT

  3. Divisions of the Nervous System

  4. Peripheral Nervous System • AFFERENT division – INPUT from sensory receptors to the brain • EFFERENT division – OUTPUT from the brain to effector organs

  5. Efferent division of the PNS • 1. SOMATIC BRANCH – output to skeletal muscle. VOLUNTARY • 2. AUTONOMIC BRANCH – output to smooth muscles and glands. INVOLUNTARY

  6. Autonomic Nervous System • There are two branches, both are involuntary • 1. SYMPATHETIC NS – flight, fight, or flee • 2. PARASYMPATHETIC NS – rest and repose

  7. Nervous Tissue • NEURONS – responsible for transfer and processing of information • SUPPORT CELLS (NEUROGLIA) – isolates the neurons, supporting framework for the neural tissue. Five times as many support cells as neurons

  8. Neuron

  9. Neurons and support cells

  10. Neuron

  11. Pyramidal cells

  12. Sir Stephen Hawking Amyotropic lateral sclerosis (ALS) Degeneration of motor neurons Complete lack of voluntary muscle control Cognitive abilities uneffected Pyramidal cell degeneration

  13. Neuron Structure

  14. Neuron structure

  15. Functional Classification of Neurons • 1. Sensory neurons – unipolar in structure, cell bodies outside the CNS, form the afferent division of the PNS, carry impulses to the CNS • 2. Motor neurons – multipolar in structure, form the efferent division of the nervous system, cell bodies inside the CNS, impulses away from the CNS • 3. Interneurons – multipolar in structure, most numerous type of neuron, inside the CNS, association neurons

  16. Function classification of neurons

  17. Functional classification of neurons

  18. Inside the CNS 1. Astrocytes 2. Microglia 3. Oligodendrocytes 4. Ependymal cells Outside the CNS 1. Satellite cells 2. Schwann cells Neuroglia Cells

  19. Neuroglia

  20. Schwann cell(Neurolemmocyte) • Support cell of the PNS • Associated with all axons of the PNS • On some axons the Schwann cell wraps around the axon to from the myelin sheath • Typically a Schwann cell can cover or myelinate about 1mm of axon length • Space between the myelin sheath is the Node of Ranvier also called the neurofibril node • On other axons the Schwann cell is merely associated with the axon and does not wrap around – unmyelinated axons • Presence of the sheath is to “insulate” the axons and speed up rate of nerve conduction

  21. Myelin sheath

  22. Myelinated and unmyelinated axons

  23. Node of Ranvier(myelin sheath gap)

  24. Myelin Sheath

  25. Node of Ranvier

  26. Jumping the node

  27. Astrocytes • CNS support cell • Blood-brain barrier • Structural support • Repair damaged neural tissue • Neuron development • Create 3-D framework for the CNS

  28. Neurons and Synapses

  29. Lots of possible synapses

  30. Nerve • Collection of long axons in the PNS • Composed of nerve fascicles • Nerves contain both sensory and motor fibers • Nerve has three layers of covers • 1. Epineurium • 2. Perineurium • 3. Endoneurium

  31. Nerve structure

  32. Nerve cross sectiona=epineuriumb=perineurium

  33. Endoneurium • Connective tissue cover around each axon in the fascicle

  34. Organization of the Nervous System

  35. Reflex Arc

  36. Reflex arc

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