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ppt on CNS

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ppt on CNS

  1. 1. Central Nervous System (CNS)Central Nervous System (CNS) BrainBrain Spinal CordSpinal Cord Peripheral Nervous System (PNS)Peripheral Nervous System (PNS) Sensory NeuronsSensory NeuronsMotor NeuronsMotor Neurons Somatic Nervous System • voluntary movements via skeletal muscles Somatic Nervous System • voluntary movements via skeletal muscles Autonomic Nervous System • organs, smooth muscles Autonomic Nervous System • organs, smooth muscles Sympathetic - “Fight-or-Flight” responses Sympathetic - “Fight-or-Flight” responses Parasympathetic - maintenance Parasympathetic - maintenance The Nervous System Nervous SystemNervous System
  2. 2. 1. CENTRAL NERVOUS SYSTEM MR.ASHOK BISHNOIMR.ASHOK BISHNOI Assist., Professor ,JINRAssist., Professor ,JINR
  3. 3. • Astrocytes:- • Abundant, star-shaped cells • Brace neurons • Form barrier between capillaries and neurons • Control the chemical environment of the brain (CNS)
  4. 4. • Microglia • Spider-like phagocytes • Dispose of debris • Ependymal cells • Line cavities of the brain and spinal cord • Circulate cerebrospinal fluid
  5. 5. • Oligodendrocytes Produce myelin sheath around nerve fibers in the CNS
  6. 6. •The central nervous system (CNS) consists of the brain & spinal cord. • The brainstem connects the brain to the spinal cord. • Communication to the peripheral nervous system (PNS) is by way of the spinal cord
  7. 7. • The meninges • Membranes covering brain & spinal cord • Protect the CNS Three (3) layers of tissue:- • Dura mater ( outer layer) • “Tough mother” • Venous sinuses • Arachnoid mater ( middle layer) • “Spider mother” • Space contains cerebrospinal fluid (CSF) • Pia mater ( inner layer) • “Little mother” • Encapsulates blood vessels
  8. 8. Subdural space Space between dura and arachnoid mater. Epidural space Space superior to dura. Subarachnoid space Space between arachnoid & pia mater Filled with CSF Contains the blood vessels supplying brain.
  9. 9. 10 Spinal cord Spinal cord Pia mater Arachnoid mater Dura mater Dorsal root Dorsal root Spinal nerve Epidural space (a) (b) Ventral root Dorsal root ganglion Thoracic vertebra Spinal nerve Dorsal root ganglion Subarachnoid space Dorsal branch (dorsal ramus) Ventral branch (ventral ramus) Ventral root Epidural space Body of vertebra
  10. 10. 11 • There are four (4) ventricles • It is interconnected cavities within cerebral hemispheres and brain stem • The ventricles are continuous with the central canal of the spinal cord • They are filled with CSF • The four (4) ventricles are: • Lateral ventricles (2) • Known as the first and second ventricles • Third ventricle (1) • Fourth ventricle (1) • Interventricular foramen • Cerebral aqueduct Lateral ventricle Third ventricle Fourth ventricle (a) Interventricular foramen Cerebral aqueduct To central canal of spinal cord Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Third ventricle (b) Cerebral aqueduct To central canal of spinal cord Fourth ventricle Lateral ventricle Interventricular foramen
  11. 11. • Secretion of CSF-by the choroid plexus •About 0.5 ml /mt •About 20ml/hrs •About 500-720 ml/day •Specific gravity is 1.005 •pH of CSF is -7.33 •It is clear ,colorless alkaline fluid present in Subarachnoid space, ventricles of brain ,Central canal of spinal cord. •Completely surrounds the brain and spinal cord
  12. 12. Composition of CSF:- •Water •Glucose •Protein •Nitrogen substance •Electrolyte eg. Na,K,Cal,Chloride etc. •Cell (few)
  13. 13. Process of CSF •CSF secreted by choroid plexus with in the cerebral ventricles (rt & lt) by ultra- filtration o& active secretion. •From Rt & Lt lateral ventricle Foramina •Third ventricle Cerebral aqueduct •Fourth ventricle Foramina lushka & Foramina magendia •Sub arachnoid space •Absorbe in the sinus
  14. 14. Function of CSF:- 1.Support the brain & spinal cord 2.Protect the brain & spinal cord 3.Maintain pressure around structure 4.Keep brain & spinal cord moist 5.Conveys nutrition to brain & spinal cord 6.Remove waste product of brain & spinal cord
  15. 15. Regions of the BrainRegions of the Brain • Cerebral hemispheres • Diencephalon • Brain stem • Cerebellum
  16. 16. Cerebral Hemispheres (Cerebrum)Cerebral Hemispheres (Cerebrum) SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Paired (left and right) superior parts of the brain • Include more than half of the brain mass Figure 7.13a
  17. 17. Cerebral Hemispheres (Cerebrum)Cerebral Hemispheres (Cerebrum) SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • The surface is made of ridges (gyri) and grooves (sulci) Figure 7.13a
  18. 18. Lobes of the CerebrumLobes of the Cerebrum SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Fissures (deep grooves) divide the cerebrum into lobes • Surface lobes of the cerebrum •Frontal lobe •Parietal lobe •Occipital lobe •Temporal lobe
  19. 19. Lobes of the CerebrumLobes of the Cerebrum SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 7.15a
  20. 20. Specialized Areas of the CerebrumSpecialized Areas of the Cerebrum Slide 7.30Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Somatic sensory area – receives impulses from the body’s sensory receptors • Primary motor area – sends impulses to skeletal muscles • Broca’s area – involved in our ability to speak
  21. 21. Sensory and Motor Areas of theSensory and Motor Areas of the Cerebral CortexCerebral Cortex Slide 7.31Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 7.14
  22. 22. Specialized Area of the CerebrumSpecialized Area of the Cerebrum SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Cerebral areas involved in special senses •Gustatory area (taste) •Visual area •Auditory area •Olfactory area
  23. 23. Specialized Area of the CerebrumSpecialized Area of the Cerebrum SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Interpretation areas of the cerebrum •Speech/language region •Language comprehension region •General interpretation area
  24. 24. Specialized Area of the CerebrumSpecialized Area of the Cerebrum SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 7.13c
  25. 25. Layers of the CerebrumLayers of the Cerebrum SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Gray matter •Outer layer •Composed mostly of neuron cell bodies Figure 7.13a
  26. 26. Layers of the CerebrumLayers of the Cerebrum SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • White matter •Fiber tracts inside the gray matter •Example: corpus callosum connects hemispheres Figure 7.13a
  27. 27. Layers of the CerebrumLayers of the Cerebrum SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Basal nuclei – internal islands of gray matter • Regulates voluntary motor activities by modifying info sent to the motor cortex • Problems = ie unable to control muscles, spastic, jerky • Involved in Huntington’s and Parkinson’s Disease Figure 7.13a
  28. 28. DiencephalonDiencephalon SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Sits on top of the brain stem • Enclosed by the cerebral heispheres • Made of three parts •Thalamus •Hypothalamus •Epithalamus
  29. 29. DiencephalonDiencephalon SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 7.15
  30. 30. ThalamusThalamus Slide 7.35Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Surrounds the third ventricle • The relay station for sensory impulses • Transfers impulses to the correct part of the cortex for localization and interpretation
  31. 31. HypothalamusHypothalamus SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Under the thalamus • Important autonomic nervous system center •Helps regulate body temperature •Controls water balance •Regulates metabolism
  32. 32. HypothalamusHypothalamus SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • An important part of the limbic system (emotions) • The pituitary gland is attached to the hypothalamus
  33. 33. EpithalamusEpithalamus Slide 7.37Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Forms the roof of the third ventricle • Houses the pineal body (an endocrine gland) • Includes the choroid plexus – forms cerebrospinal fluid
  34. 34. Brain StemBrain Stem SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Attaches to the spinal cord • Parts of the brain stem •Midbrain •Pons •Medulla oblongata
  35. 35. Brain StemBrain Stem SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 7.15a
  36. 36. MidbrainMidbrain Slide 7.39Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Mostly composed of tracts of nerve fibers •Reflex centers for vision and hearing •Cerebral aquaduct – 3rd -4th ventricles
  37. 37. PonsPons Slide 7.40Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • The bulging center part of the brain stem • Mostly composed of fiber tracts • Includes nuclei involved in the control of breathing
  38. 38. Medulla OblongataMedulla Oblongata Slide 7.41Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • The lowest part of the brain stem • Merges into the spinal cord • Includes important fiber tracts • Contains important control centers •Heart rate control •Blood pressure regulation •Breathing •Swallowing •Vomiting
  39. 39. CerebellumCerebellum SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Two hemispheres with convoluted surfaces • Provides involuntary coordination of body movements
  40. 40. CerebellumCerebellum SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 7.15a
  41. 41. Protection of the Central NervousProtection of the Central Nervous SystemSystem SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Scalp and skin • Skull and vertebral column • Meninges Figure 7.16a
  42. 42. Protection of the Central NervousProtection of the Central Nervous SystemSystem SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Cerebrospinal fluid • Blood brain barrier Figure 7.16a
  43. 43. MeningesMeninges SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Dura mater •Double-layered external covering •Periosteum – attached to surface of the skull •Meningeal layer – outer covering of the brain •Folds inward in several areas
  44. 44. MeningesMeninges SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Arachnoid layer •Middle layer •Web-like • Pia mater •Internal layer •Clings to the surface of the brain
  45. 45. Cerebrospinal FluidCerebrospinal Fluid Slide 7.46Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Similar to blood plasma composition • Formed by the choroid plexus • Forms a watery cushion to protect the brain • Circulated in arachnoid space, ventricles, and central canal of the spinal cord
  46. 46. Ventricles and Location of theVentricles and Location of the Cerebrospinal FluidCerebrospinal Fluid SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 7.17a
  47. 47. Ventricles and Location of theVentricles and Location of the Cerebrospinal FluidCerebrospinal Fluid SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 7.17b
  48. 48. Blood Brain BarrierBlood Brain Barrier Slide 7.48Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Includes the least permeable capillaries of the body • Excludes many potentially harmful substances • Useless against some substances •Fats and fat soluble molecules •Respiratory gases •Alcohol •Nicotine •Anesthesia
  49. 49. Traumatic Brain Injuries (TBI)Traumatic Brain Injuries (TBI) Slide 7.49Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Concussion •Slight or mild brain injury •Bleeding & tearing of nerve fibers happened •Recovery likely with some memory loss • Contusion •A more severe TBI •Nervous tissue destruction occurs •Nervous tissue does not regenerate • Cerebral edema
  50. 50. • Cerebral edema – Swelling from the inflammatory response – May compress and kill brain tissue • Subdural hematoma – Collection of blood below the dura • Standards for these conditions were revised in 2004. Please check out TBIs at Mayoclinic.com for more current information on diagnostic terminology.
  51. 51. Cerebrovascular Accident (CVA)Cerebrovascular Accident (CVA) Slide 7.50Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Commonly called a stroke • The result of a ruptured blood vessel supplying a region of the brain • Brain tissue supplied with oxygen from that blood source dies • Loss of some functions or death may result
  52. 52. Alzheimer’s DiseaseAlzheimer’s Disease Slide 7.51Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Progressive degenerative brain disease • Mostly seen in the elderly, but may begin in middle age • Structural changes in the brain include abnormal protein deposits and twisted fibers within neurons • Victims experience memory loss, irritability, confusion and ultimately, hallucinations and death
  53. 53. Spinal CordSpinal Cord Slide 7.52Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Extends from the medulla oblongata to the region of T12 • Below T12 is the cauda equina (a collection of spinal nerves) • Enlargements occur in the cervical and lumbar regions Figure 7.18
  54. 54. Spinal Cord AnatomySpinal Cord Anatomy SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Exterior white mater – conduction tracts Figure 7.19
  55. 55. Spinal Cord AnatomySpinal Cord Anatomy SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Internal gray matter - mostly cell bodies •Dorsal (posterior) horns •Anterior (ventral) horns Figure 7.19
  56. 56. Spinal Cord AnatomySpinal Cord Anatomy SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Central canal filled with cerebrospinal fluid Figure 7.19
  57. 57. Spinal Cord AnatomySpinal Cord Anatomy Slide 7.54Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Meninges cover the spinal cord • Nerves leave at the level of each vertebrae •Dorsal root • Associated with the dorsal root ganglia – collections of cell bodies outside the central nervous system •Ventral root
  58. 58. Peripheral Nervous SystemPeripheral Nervous System Slide 7.55Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Nerves and ganglia outside the central nervous system • Nerve = bundle of neuron fibers • Neuron fibers are bundled by connective tissue
  59. 59. Structure of a NerveStructure of a Nerve Slide 7.56Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Endoneurium surrounds each fiber • Groups of fibers are bound into fascicles by perineurium • Fascicles are bound together by epineurium Figure 7.20
  60. 60. Classification of NervesClassification of Nerves Slide 7.57Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Mixed nerves – both sensory and motor fibers • Afferent (sensory) nerves – carry impulses toward the CNS • Efferent (motor) nerves – carry impulses away from the CNS
  61. 61. Spinal NervesSpinal Nerves Slide 7.63Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • There is a pair of spinal nerves at the level of each vertebrae.
  62. 62. Spinal NervesSpinal Nerves Slide 7.64Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 7.22a
  63. 63. Autonomic Nervous SystemAutonomic Nervous System Slide 7.67Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • The involuntary branch of the nervous system • Consists of only motor nerves • Divided into two divisions •Sympathetic division •Parasympathetic division
  64. 64. Comparison of Somatic andComparison of Somatic and Autonomic Nervous SystemsAutonomic Nervous Systems Slide 7.69Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 7.24
  65. 65. Anatomy of the Autonomic NervousAnatomy of the Autonomic Nervous SystemSystem Slide 7.73Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 7.25
  66. 66. Autonomic FunctioningAutonomic Functioning SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Sympathetic – “fight-or-flight” •Response to unusual stimulus •Takes over to increase activities •Remember as the “E” division = exercise, excitement, emergency, and embarrassment
  67. 67. Autonomic FunctioningAutonomic Functioning SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Parasympathetic – housekeeping activites •Conserves energy •Maintains daily necessary body functions •Remember as the “D” division - digestion, defecation, and diuresis
  68. 68. Development Aspects of theDevelopment Aspects of the Nervous SystemNervous System SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • The nervous system is formed during the first month of embryonic development • Any maternal infection can have extremely harmful effects • The hypothalamus is one of the last areas of the brain to develop
  69. 69. Development Aspects of theDevelopment Aspects of the Nervous SystemNervous System SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • No more neurons are formed after birth, but growth and maturation continues for several years (new evidence!) • The brain reaches maximum weight as a young adult • However, we can always grow dendrites!

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