The central nervous system (CNS) consists of the brain and spinal cord. The brain is divided into regions including the cerebral hemispheres, diencephalon, brain stem, and cerebellum. The CNS is protected by meninges and cerebrospinal fluid. The peripheral nervous system (PNS) connects the CNS to the rest of the body and is divided into the somatic and autonomic nervous systems. Together, the CNS and PNS use neurons and glial cells to control bodily functions and process sensory information.

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. 1. CENTRAL
NERVOUS SYSTEM
MR.ASHOK BISHNOIMR.ASHOK BISHNOI
Assist., Professor ,JINRAssist., Professor ,JINR

3. • Astrocytes:-
• Abundant, star-shaped cells
• Brace neurons
• Form barrier
between capillaries
and neurons
• Control the chemical
environment of
the brain (CNS)

4. • Microglia
• Spider-like phagocytes
• Dispose of debris
• Ependymal cells
• Line cavities of the
brain and spinal cord
• Circulate
cerebrospinal
fluid

5. • Oligodendrocytes
Produce myelin
sheath around
nerve fibers in the
CNS

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. • 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. 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.

10. 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

11. 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

15. • 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

16. Composition of CSF:-
•Water
•Glucose
•Protein
•Nitrogen substance
•Electrolyte eg. Na,K,Cal,Chloride etc.
•Cell (few)

17. 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

18. 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

20. Regions of the BrainRegions of the Brain
• Cerebral
hemispheres
• Diencephalon
• Brain stem
• Cerebellum

21. 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

22. 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

23. Lobes of the CerebrumLobes of the Cerebrum
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• Fissures (deep grooves) divide the
cerebrum into lobes
• Surface lobes of the cerebrum
•Frontal lobe
•Parietal lobe
•Occipital lobe
•Temporal lobe

24. Lobes of the CerebrumLobes of the Cerebrum
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Figure 7.15a

25. Specialized Areas of the CerebrumSpecialized Areas of the Cerebrum
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• 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

27. Sensory and Motor Areas of theSensory and Motor Areas of the
Cerebral CortexCerebral Cortex
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Figure 7.14

28. Specialized Area of the CerebrumSpecialized Area of the Cerebrum
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• Cerebral areas involved in special
senses
•Gustatory area (taste)
•Visual area
•Auditory area
•Olfactory area

29. Specialized Area of the CerebrumSpecialized Area of the Cerebrum
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• Interpretation areas of the cerebrum
•Speech/language region
•Language comprehension region
•General interpretation area

30. Specialized Area of the CerebrumSpecialized Area of the Cerebrum
SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 7.13c

31. Layers of the CerebrumLayers of the Cerebrum
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• Gray matter
•Outer layer
•Composed
mostly of neuron
cell bodies
Figure 7.13a

32. 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

33. Layers of the CerebrumLayers of the Cerebrum
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• 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

34. DiencephalonDiencephalon
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• Sits on top of the brain stem
• Enclosed by the cerebral heispheres
• Made of three parts
•Thalamus
•Hypothalamus
•Epithalamus

35. DiencephalonDiencephalon
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Figure 7.15

36. 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

37. HypothalamusHypothalamus
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• Under the thalamus
• Important autonomic nervous system
center
•Helps regulate body temperature
•Controls water balance
•Regulates metabolism

38. HypothalamusHypothalamus
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• An important part of the limbic system
(emotions)
• The pituitary gland is attached to the
hypothalamus

39. EpithalamusEpithalamus
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• Forms the roof of the third ventricle
• Houses the pineal body (an endocrine
gland)
• Includes the choroid plexus – forms
cerebrospinal fluid

40. Brain StemBrain Stem
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• Attaches to the spinal cord
• Parts of the brain stem
•Midbrain
•Pons
•Medulla oblongata

41. Brain StemBrain Stem
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Figure 7.15a

42. 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

43. 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

44. 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

45. CerebellumCerebellum
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• Two hemispheres with convoluted
surfaces
• Provides involuntary coordination of
body movements

46. CerebellumCerebellum
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Figure 7.15a

47. Protection of the Central NervousProtection of the Central Nervous
SystemSystem
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• Scalp and skin
• Skull and vertebral column
• Meninges
Figure 7.16a

48. 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

49. MeningesMeninges
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• 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

50. MeningesMeninges
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• Arachnoid layer
•Middle layer
•Web-like
• Pia mater
•Internal layer
•Clings to the surface of the brain

51. 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

52. Ventricles and Location of theVentricles and Location of the
Cerebrospinal FluidCerebrospinal Fluid
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Figure 7.17a

53. Ventricles and Location of theVentricles and Location of the
Cerebrospinal FluidCerebrospinal Fluid
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Figure 7.17b

54. 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

55. 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

56. • 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.

57. 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

58. 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

59. 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

60. Spinal Cord AnatomySpinal Cord Anatomy
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• Exterior white mater – conduction tracts
Figure 7.19

61. Spinal Cord AnatomySpinal Cord Anatomy
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• Internal gray matter - mostly cell bodies
•Dorsal (posterior) horns
•Anterior (ventral) horns
Figure 7.19

62. Spinal Cord AnatomySpinal Cord Anatomy
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• Central canal filled with cerebrospinal
fluid
Figure 7.19

63. 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

64. 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

65. 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

66. Classification of NervesClassification of Nerves
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• Mixed nerves – both sensory and motor
fibers
• Afferent (sensory) nerves – carry
impulses toward the CNS
• Efferent (motor) nerves – carry impulses
away from the CNS

67. Spinal NervesSpinal Nerves
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• There is a pair of spinal nerves at the
level of each vertebrae.

68. Spinal NervesSpinal Nerves
Slide 7.64Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 7.22a

69. 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

70. 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

71. Anatomy of the Autonomic NervousAnatomy of the Autonomic Nervous
SystemSystem
Slide 7.73Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 7.25

72. Autonomic FunctioningAutonomic Functioning
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• Sympathetic – “fight-or-flight”
•Response to unusual stimulus
•Takes over to increase activities
•Remember as the “E” division = exercise,
excitement, emergency, and
embarrassment

73. Autonomic FunctioningAutonomic Functioning
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• Parasympathetic – housekeeping
activites
•Conserves energy
•Maintains daily necessary body functions
•Remember as the “D” division - digestion,
defecation, and diuresis

74. Development Aspects of theDevelopment Aspects of the
Nervous SystemNervous System
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• 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

75. 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!