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Nervous System

Nervous System . Chapter 9. Nervous System. Internal communication system Conveys sensory information Sends controlling (motor) information 2 main divisions Central nervous system Brain & Spinal cord Periphieral nervous system Nerve network. Nervous System. Central Nervous System.

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Nervous System

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  1. Nervous System Chapter 9

  2. Nervous System • Internal communication system • Conveys sensory information • Sends controlling (motor) information • 2 main divisions • Central nervous system • Brain & Spinal cord • Periphieral nervous system • Nerve network

  3. Nervous System

  4. Central Nervous System • Components • Brain • Spinal cord • Functions • Stimuli integration & processing • Higher brain functions • Coordinate appropriate response

  5. Stimuli Integration & Processing • Internal • Temperature, blood pressure, pH, O2, CO2 • External • Light, sound, touch, taste

  6. External Stimuli Processing

  7. Internal Stimuli Processing

  8. Coordinate Appropriate Response • Control target aka effector tissues • Muscle- contractions • Nerves- neural signal • Gland- secretions • “motor responses”

  9. Higher Brain Functions • Memory • Cognition- conscious thought • Problem solving • Communication- speech

  10. Peripheral Nervous System • Groups of functional nerves • Cranial nerves • Exit/ enter brain • Spinal nerves • Exit enter spinal cord • Function • Perceive environmental changes • Internal or external • Sends (transduce) • Sensory stimuli to CNS • Motor stimuli to effectors • Muscles/ glands

  11. Peripheral Nerves Branch off brain or spinal cord

  12. Peripheral Nerves are extensive

  13. Peripheral Nerve Types • Defined by direction of information • Afferent (sensory) nerves • Carry sensory information to CNS • Ascending nerves • Efferent (motor) nerves • Carry motor information to peripheral effectors

  14. Afferent Efferent

  15. Nervous System Functional Classification

  16. Nervous System • Somatic nervous system (SNS) • Conscious information • Responds to sensory stimuli • Sight, sound, touch, etc • Motor stimuli • Skeletal muscle only • Autonomic nervous system (ANS) • Unconscious information • Sensory stimuli • Blood pressure, body temp • Motor stimuli • Smooth muscle & glands

  17. Nervous System Divisions

  18. Autonomic Nervous System • Unconscious stimuli processing • Regulates homeostasis • Visceral motor neurons • Effector tissues • Cardiac & smooth muscle • Glands • 3 Divisions • Sympathetic • Parasympathetic • Enteric • Dual Ennervation • Fight or Flight

  19. Divisions of Autonomic NS • Sympathetic (SNS) • Fight or Flight • Parasympathetic (PNS) • Rest and digest • Enteric • Local digestive pathways

  20. Dual Ennervation

  21. Autonomic Nerves • Visceral motor control using at least two neurons • Visceral motor neuron from CNS • Preganglionic Neurons • Peripheral neuron to effector tissue • Postganglionic Neuron (Ganglionic) • Cell body outside of CNS • Autonomic ganglia • Contains synapse between pre & postganglionic nerves • Outside of CNS • Location varies with division of ANS

  22. Autonomic Nerve Morphology

  23. SNS vs. PNS Ganglia

  24. Sympathetic Nervous System • AKA Thoracolumbar division • Preganglionic nerves emerge from CNS at thoracic & lumbar regions • Typically stimulatory pathways that prepare the body for exertion, stress, or emergency • Fight or Flight response • Stimulates tissue metabolism, increases alertness • Designed for rapid “whole body” response • Multiple ennervation pathways • Branched neurons • Coordinates with endocrine system to release adrenaline

  25. Fight or Flight Response • Dilates pupils • Increase heart rate, incr contaction force, incr blood pressure • Decrease blood flow to nonessential organs • Increase blood flow to skeletal & cardiac muscle • Brochodialation, incr respiratory rate • Blood glucose level increase

  26. Sympathetic Pathways

  27. Sympathetic Pathways • Sympathetic chain ganglia • Aka paravertebral/ lateral ganglia • Lateral to vertebral column • Target effectors in thoracic cavity, head, neck, limbs • Collateral ganglia • Aka prevertebral ganglia • Anterior to vertebral column • Target effectors in abdominopelvic cavity • Adrenal gland • Modified ganglia in adrenal medulla • Stimulates release of neurotransmitter into blood stream to act as hormone • Acts on tissues without SNS neuronal supply • Stimulates widespread longer lasting response

  28. Sympathetic Chain Ganglia (Paravertebral)

  29. Collateral Ganglia

  30. Adrenal Sympathetic Fibers

  31. Parasympathetic Nervous System • Aka Craniosacral • Preganglionic nerves emerge from CNS at brainstem & sacrum regions • Parasympathetic pathways that return the body to normal conditions after exertion, stress, or emergency • Rest and Digest response • May counteract SNS activities (typ dominates) • Promotes sedentary activities • food processing, relaxation, energy absorption, & reproduction • Designed for localized response • Direct ennervation pathways • Non-branched neurons • Autonomic ganglia located close to effector tissue • Terminal ganglia • Intramural ganglia

  32. Paraympathetic Pathways

  33. Rest & Digest • Pathways that restore body after fight/flight & conserve energy • Increase salivation, lacrimation, urination, digestion, defecation (SLUDD) • Decreases heart rate, bronchioconstricts • Constricts pupil • Paradoxical fear • When there is no escape route or way to win • Mass activation • Loss of control over urination & defication

  34. Parasympathetic Neurons

  35. Enteric Nervous System • Highly branched network of neurons ennervating tunics of the digestive system • Activities influenced by stimulated by activities of SNS & PNS • Local response to stimuli independent of CNS • Involved in visceral reflexes

  36. Enteric Nervous System

  37. Nervous System Composition • Neuron • Nerve cell • Highly specialized for carrying information • Electrical signal • Action potential • Neuroglia • “Helper cells” • Support, nourish, protect, & assist neurons • 5X more numerous

  38. Neuron

  39. Neuron Diversity Sensory Neurons

  40. Neuroglia

  41. Mechanical support Supply nutrients Supply glucose from blood supply Maintain extracellular environment Secretion & absorption of neurotransmitters Maintain blood brain barrier Wrap around endothelium Digest & eliminate debris Digest non regenerative CNS cells that are damaged create scar Connect to each other w/ gap junctions Functional syncytium Astrocytes

  42. Astrocytes

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