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Tanveer Raza MD MS MBBS razajju2@yahoo

Physiology Lecture 11. Tanveer Raza MD MS MBBS razajju2@yahoo.com. Neuroglia. Definition Non-excitable supporting connective tissues present in nervous system Numerous in number (10-50 times of neurons) Classification Micorglia Macroglia. Neuroglia: Classification. Microglia

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Tanveer Raza MD MS MBBS razajju2@yahoo

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  1. Physiology Lecture 11 Tanveer Raza MD MS MBBS razajju2@yahoo.com

  2. Neuroglia • Definition • Non-excitable supporting connective tissues present in nervous system • Numerous in number (10-50 times of neurons) • Classification • Micorglia • Macroglia Tanveer Raza MD MS MBBS razajju2@yahoo.com

  3. Neuroglia: Classification • Microglia Scavanger cells that resemble tissue macrophages • Macroglia Tanveer Raza MD MS MBBS razajju2@yahoo.com

  4. Neuroglia: Classification • Microglia • Macroglia • Astrocytes • Oligodendrocytes • Myelin formation • Glioblast Outside the central nervous system there are some other specialized support cells called Schwann cells Tanveer Raza MD MS MBBS razajju2@yahoo.com

  5. Neuroglia: Classification • Microglia • Macroglia • Astrocytes • Fibrous • Primarily in white matter • Protoplasmic • Gray matter Tanveer Raza MD MS MBBS razajju2@yahoo.com

  6. Neuroglia: Function • Supporting • Insulation • Phagocytosis • Formation of myelin sheath Fibrous Astrocytes: Astrocyte processes surround blood vessels and capillaries. This is an important component of the so-called blood-brain barrier Tanveer Raza MD MS MBBS razajju2@yahoo.com

  7. Myelinogenesis • Process of formation and deposition of myelin sheath around a nerve fiber is called myelinogenesis • In PNS • Schwann cells • In CNS • Oligodendrocytes Tanveer Raza MD MS MBBS razajju2@yahoo.com

  8. Myelinated nerve fiber: Wrapping of a Schwann cell membrane around a large axon to form the myelin sheath of the myelinated nerve fiber Myelinogenesis Tanveer Raza MD MS MBBS razajju2@yahoo.com

  9. Unmyelinated nerve fibers: Partial wrapping of the membrane and cytoplasm of a Schwann cell around multiple unmyelinated nerve fibers Myelinogenesis Tanveer Raza MD MS MBBS razajju2@yahoo.com

  10. Myelinogenesis: PNS Deposition of myelin sheath around the axon by Schwann cells: The membrane of a Schwann cell first envelops the axon. Then the Schwann cell rotates around the axon many times, laying down multiple layers of Schwann cell membrane containing the lipid substance sphingomyelin. This substance is an excellent electrical insulator. Tanveer Raza MD MS MBBS razajju2@yahoo.com

  11. Myelinogenesis: CNS Tanveer Raza MD MS MBBS razajju2@yahoo.com

  12. Node of Ranvier • At the juncture between two successive Schwann cells along the axon, a small uninsulated area, ions can flow with ease This area is called the node of Ranvier Tanveer Raza MD MS MBBS razajju2@yahoo.com

  13. Node of Ranvier:Saltatory Conduction • Flow of electrical current along a myelinated axon from node to node • Importance • Increases velocity of nerve transmission • Conserves energy for axon • Allow repolarization to occur with verylittle transfer of ions Tanveer Raza MD MS MBBS razajju2@yahoo.com

  14. Node of Ranvier:Saltatory Conduction Tanveer Raza MD MS MBBS razajju2@yahoo.com

  15. Reflex Arc Tanveer Raza MD MS MBBS razajju2@yahoo.com Tanveer Raza MD MS

  16. The Nervous System • Central Nervous System • Brain • Forebrain • Midbrain • Hindbrain • Spinal Cord • Peripheral nervous System [Somatic and Autonomic] • Spinal nerve and their ganglia • Cranial nerves and their ganglia Tanveer Raza MD MS MBBS razajju2@yahoo.com

  17. Tanveer Raza MD MS MBBS razajju2@yahoo.com

  18. Peripheral Nervous System Somatic & Autonomic Nervous System constantly work together to regulate body organs and maintain normal internal functions AUTONOMIC SOMATIC Tanveer Raza MD MS MBBS razajju2@yahoo.com

  19. Peripheral Nervous System • Autonomic Nervous System • Two neurons, • preganglionic neuron • postganglionic neuron • Skeletal motor pathway • a single neuron Tanveer Raza MD MS MBBS razajju2@yahoo.com

  20. Peripheral Nervous System Tanveer Raza MD MS MBBS razajju2@yahoo.com

  21. Peripheral Nervous System Tanveer Raza MD MS MBBS razajju2@yahoo.com

  22. Peripheral Nervous System • Somatic Nervous System • Under conscious control • Uses both somatic sensory and somatic motor neurons to conduct stimulus information from a sensory receptor, such as tactile receptor in the skin • Innervates skeletal muscle fibers • Autonomic Nervous System Tanveer Raza MD MS MBBS razajju2@yahoo.com

  23. Peripheral Nervous System • Somatic Nervous System • Autonomic Nervous System • Involuntary • Also utilizes sensory and motor neurons • Visceral sensory neurons provide input for activation Tanveer Raza MD MS MBBS razajju2@yahoo.com Tanveer Raza MD MS

  24. Autonomic Nervous System Tanveer Raza MD MS

  25. Autonomic Nervous System ANS is a complex system of nerves that govern involuntary actions Tanveer Raza MD MS MBBS razajju2@yahoo.com Tanveer Raza MD MS

  26. Autonomic Nervous System • Division • Parasympathetic • Sympathetic Tanveer Raza MD MS MBBS razajju2@yahoo.com

  27. Autonomic Nervous System • Both …. • have a preganglionic and post ganglionic neuron • contain the autonomic ganglia that contain the ganglionic neurons • are involuntary and concerned with body’s internal environment • But have dramatically different functions Tanveer Raza MD MS MBBS razajju2@yahoo.com Tanveer Raza MD MS

  28. Thank You

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