system organ The human body is made up of

muscle

1. Anatomy, Histology, & Genetics l Physiology
The Nervous System

2. Functions of the Nervous System
1. Received sensory input –gathering information
•To monitor changes occurring inside and outside the
body (changes = stimuli)
2. Integration or integrating information
•to process and interpret sensory input and decide if
action is needed.
3. Motor output/controlling muscles and glands
•A response to integrated stimuli
•The response activates muscles or glands
4. Maintaining homeostasis (stimulate or inhibit other system)
5. Establishing/Maintaining Mental Activity (consciousness, memory,
thinking)

3. Organization of the Nervous System

4. Organization of the Nervous System

5. Structural Classification of the Nervous System

6. Functional Classification of the
Peripheral Nervous System
•Sensory (afferent) division
•Nerve fibers that carry information tothe
central nervous system

7. Functional Classification of the
Peripheral Nervous System
•Motor (efferent) division
•Nerve fibers that carry impulses away from
the central nervous system
S A M E

8. Functional Classification of the
Peripheral Nervous System
•Motor (efferent) division
•Two subdivisions
•Somatic nervous system = voluntary
•Autonomic nervous system = involuntary

9. Nervous Tissue: Support Cells
(Neuroglia or Glia)
•Astrocytes (satellite cells in PNS)
•Abundant, star-shaped cells
•Major supporting cells in CNS
•Brace neurons
•Form barrier between capillaries
and neurons
•Control the chemical environment of the brain
(CNS), participate with the blood vessel
endothelium to form a permeability barrier (the
blood-brain barrier).

10. Nervous Tissue: Support Cells
•Microglia (CNS)
•Spider-like phagocytes
•Dispose of debris (act as
macrophages)
•Immune cells of the CNS (brain
infections & inflammation)
•Ependymal cells (CNS)
•Line cavities of the
brain and spinal cord
•Circulate
cerebrospinal
fluid
•Line the ventricles of the brain

11. Nervous Tissue: Support Cells
•Oligodendrocytes
(CNS)
•Produce myelin
sheath around
nerve fibers in the
central nervous
system

12. Nervous Tissue: Support Cells
•Neuroglia divide.
•Neurons do not.
•Most brain tumors are
“gliomas.”
•Most brain tumors involve the
neuroglia cells, not the
neurons.
Neuroglia vs. Neurons

13. Nervous Tissue: Support Cells

14. Support Cells of the PNS
•Satellite cells (PNS)
•Protect neuron cell bodies
•Schwann cells
•Form myelin sheath in the peripheral
nervous system

15. Nervous Tissue: Neurons
•Neurons = nerve cells
•Cells specialized to transmit messages
•Major regions of neurons
•Cell body –nucleus and metabolic center of the cell
•Processes –fibers that extend from the cell body
(dendrites and axons)

16. Neuron Anatomy
•Cell body
•Nucleus
•Large
nucleolus
neuronal cytoskeleton (structure that helps
cells maintain shape and internal
organization
ribonucleic acid (RNA) and proteins in aggregate
with rough endoplasmic reticulum. Involved in
protein synthesis and cellular metabolism.

17. Neuron Anatomy
•Extensions
outside the cell
body
•Dendrites –
conduct
impulses toward
the cell body
•Axons –conduct
impulses away
from the cell
body

18. Axons and Nerve Impulses
•Axons end in axonal terminals
•Axonal terminals contain
vesicles with neurotransmitters
•Axonal terminals are separated
from the next neuron by a gap
•Synaptic cleft/gap –gap
between adjacent neurons
(gap between pre-
&postsynaptic cells.
•Synapse –junction between
nerves

19. Axons and Nerve Impulses

21. Nerve Fiber Coverings
•Schwann cells –produce
myelin sheaths in jelly-
roll like fashion
•Nodes of Ranvier –gaps
in myelin sheath along
the axon, allow
generation of a fast
electrical impulse

22. Nerve Fiber Coverings
Application
•InMultipleSclerosisthe
myelinsheathis
destroyed.
•Themyelinsheath
hardenstoatissue
calledthesclerosis.
•Thisisconsideredan
autoimmunedisease.
•WhydoesMSappearto
affectthemuscles?
Numbness or weakness in
one or more limbs.

23. Neuron Cell Body Location
•Most are found in the
central nervous system
•Gray matter –cell
bodies and
unmyelinated fibers
•Nuclei –clusters of cell
bodies within the white
matter of the central
nervous system
•Ganglia –collections of
cell bodies outside the
central nervous system

24. Functional Classification of Neurons
•Sensory (afferent) neurons
•Carry impulses from the sensory receptors
•Cutaneous sense organs
•Proprioceptors –detect stretch or tension
feedback about body and limb position
•Motor (efferent) neurons
•Carry impulses from the central nervous
system

25. Functional Classification of Neurons
•Interneurons
(association
neurons)
•Found in neural
pathways in the
central nervous
system
•Connect sensory
and motor neurons

26. Neuron Classification
Swelling on a nerve fiber, contains cell bodies
Relay station
Interconnect with other ganglia to form a plexus.

27. Structural Classification of Neurons
•Multipolar neurons –many extensions
from the cell body (spinal cord, brain, autonomic ganglia)
MostoftheneuronswithintheCNSand
nearlyallmotorneurons are multipolar,
most common type of neuron.

28. Structural Classification of Neurons
•Bipolar neurons –one axon and one
dendrite, relatively rare.
Example:Sensoryneuronsofthe
olfactoryepithelium,theretinaoftheeye,and
gangliaofthevestibulocochlearnerve.

29. Structural Classification of Neurons
•Unipolar neurons (pseudo-unipolar) –
have a short single process leaving the
cell body
Example:Sensoryneuronswithreceptorslocatedwithin
theskin,joints,muscles,andinternalorgans.Theaxonsof
suchneuronsareusuallylong,terminatinginthespinal
cord.

30. Structural Classification of Neurons

31. How Neurons Function (Physiology)
•Irritability –ability to respond to stimuli
•Conductivity –ability to transmit an
impulse
•The plasma membrane at rest is
polarized
•Fewer positive ions are inside the cell than
outside the cell.
•Resting cell, uneven charge distribution
“RESTING MEMBRANE POTENTIAL”

32. How Neurons Function (Physiology)
RESTING MEMBRANE
POTENTIAL
1.Higher concentration
of K
+
inside the cell
membrane
2.Higher concentration
of NA
+
outside the
cell membrane
3.Greater permeability
to K
+
than Na
+

33. Generating the RMP

34. The Action Potential
•If the action potential
(nerve impulse) starts,
it is propagated over
the entire axon
•Potassium ions rush
out of the neuron after
sodium ions rush in,
which repolarizes the
membrane
•The sodium-potassium
pump restores the
original configuration
•This action requires ATP

35. Voltage-Gated Ion Channels & Action Potential
•The impulse continues to move toward the cell body
•Impulses travel faster when fibers have a myelin
sheath

36. •Impulses are able to
cross the synapse to
another nerve
•Neurotransmitter is
released from a
nerve’s axon terminal
•The dendrite of the
next neuron has
receptors that are
stimulated by the
neurotransmitter
•An action potential is
started in the dendrite
Voltage-Gated Ion Channels & Action Potential

37. Voltage-Gated Ion Channels &
Action Potential

38. Voltage-Gated Ion Channels &
Action Potential

39. Propagation of Nerve Impulse

40. Propagation of Nerve Impulse

41. How Neurons Communicate at
Synapses

42. The Reflex Arc
•Reflex –rapid, predictable, and
involuntary responses to stimuli
•Reflex arc –direct route from a sensory
neuron, to an interneuron, to an effector.
Mostreflexesoccurinthespinalcordorbrainstem
ratherthaninthehigherbraincenters.Forexample,
person’sfingertouchesahotstove(withdrawal
reflex).

43. Simple Reflex Arc
knee jerk reflex withdrawal reflex

44. Types of Reflexes and Regulation
•Autonomic reflexes
•Smooth muscle regulation
•Heart and blood pressure regulation
•Regulation of glands
•Digestive system regulation
•Somatic reflexes
•Activation of skeletal muscles

45. Central Nervous System (CNS)
•CNS develops from the
embryonic neural tube
•The neural tube becomes the
brain and spinal cord
•The opening of the neural
tube becomes the ventricles
•Four ventricles within the
brain (lateral ventricles, 3
rd
ventricle, 4
th
ventricle)
•Filled with cerebrospinal
fluid

46. Central Nervous System (CNS)
Lined byependymal
cells, which form a
structure called the
choroid plexus.
It is within thechoroid
plexusthat CSF is
produced.
VENTRICLES OF THE BRAIN

47. Cerebral Hemispheres (Cerebrum)
•Paired (left
and right)
superior parts
of the brain
•Include more
than half of the
brain mass

48. Regions of the Brain
•Cerebral
hemispheres
•Diencephalon
(central portion
around the 3
rd
ventricle) (thalamus,
subthalamus hypothalamus,
epithalamus)
•Brain stem (midbrain,
pons, medulla oblongata)
•Cerebellum

49. Cerebral Hemispheres (Cerebrum)
•The surface
is made of
ridges (gyri)
and grooves
(sulci)

50. Cerebral Hemispheres (Cerebrum)

51. Lobes of the Cerebrum
•Fissures (deep grooves) divide the
cerebrum into lobes
•Surface lobes of the cerebrum
•Frontal lobe –cognitive functions/movement
•Parietal lobe -sensation
•Occipital lobe -vision
•Temporal lobe –auditory information (hearing).,
encoding of memory

52. Lobes of the Cerebrum

53. Lobes of the Cerebrum

54. Lobes of the Cerebrum

55. Specialized Areas of the Cerebrum
•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, production
of speech
•Wernicke’s area-comprehension of speech

56. BROCA’S
APHASIA
WERNICKE’S
APHASIA
GLOBAL
APHASIA

57. Sensory and Motor Areas of the
Cerebral Cortex

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

59. Specialized Area of the Cerebrum
•Interpretation areas of the cerebrum
•Speech/language region
•Language comprehension region
•General interpretation area -integrates all
signals into a single thought or understanding.

60. Specialized Area of the Cerebrum

61. Layers of the Cerebrum
•Gray matter
•Outer layer
•Composed
mostly of
neuron cell
bodies

62. Layers of the Cerebrum
•White matter
•Fiber tracts
inside the gray
matter
•Example:
corpus callosum
connects
hemispheres

63. Layers of the Cerebrum
•Basal nuclei/basal ganglia –
internal islands of gray matter
(corpus striatum, substantia
nigra)
•Regulates voluntary motor
activities by modifying info
sent to the motor cortex
(inhibit/facilitate movement)
•Problems = i.e. unable to
control muscles, spastic, jerky
•Involved in Huntington’s and
Parkinson’s Disease

64. Diencephalon
•Sits on top of the brain stem
•Enclosed by the cerebral hemispheres
•Made of three parts
•Thalamus
•Hypothalamus
•Epithalamus

65. Diencephalon

66. Thalamus
•largest part of the diencephalon.
•Surrounds the third ventricle
•The relay station for sensory
impulses
•influences mood and registers
•an unlocalized, uncomfortable
perception of pain.
•Transfers impulses to the correct
part of the cortex for localization
and interpretation

67. Hypothalamus
•inferior part of the diencephalon
•Important autonomic nervous
system center
•Helps regulate body temperature
•Controls water balance/hunger
•Regulates metabolism

68. Hypothalamus
•An important part of the limbic system
(emotions)
•The pituitary gland (master gland) is
attached to the hypothalamus
•hypothalamus plays a major role in
controlling the secretion of hormones
from the pituitary gland

69. Epithalamus
•Forms the roof of the third ventricle
•Houses the pineal body (an endocrine
gland), melatonin, sleep wake cycle
•Includes the choroid plexus –forms
cerebrospinal fluid
•emotional and visceral response to odors

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

71. Brain Stem

72. Midbrain
•Mostly composed of tracts of nerve
fibers
•Reflex centers for vision and hearing
•Cerebral aqueduct –3
rd
-4
th
ventricles

73. Pons
•The bulging center part of the brain stem
•Mostly composed of fiber tracts
•Includes nuclei involved in the control of breathing

74. Medulla Oblongata
•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

75. Cerebellum
•Two hemispheres with convoluted
surfaces
•Provides involuntary coordination of
body movements

76. Cerebellum

77. Protection of the Central Nervous
System
•Scalp and skin
•Skull and vertebral column
•Meninges

78. Protection of the Central Nervous
System
•Cerebrospinal fluid
•Blood brain barrier (shield brain from
toxic substances))

79. Meninges
•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

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

81. Cerebrospinal Fluid
•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

82. Ventricles and Location of the
Cerebrospinal Fluid

83. Cerebrospinal Fluid Flow

84. Blood Brain Barrier
•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

85. Spinal Cord
•Extends from the
medulla oblongata to
the region of L2
•Below L2 is the cauda
equina (a collection of
spinal nerves)
•Enlargements occur in
the cervical and lumbar
regions

86. Spinal Cord

87. Spinal Cord Anatomy
•Exterior white mater –conduction tracts

88. Spinal Cord Anatomy
•Internal gray matter -mostly cell bodies
•Dorsal (posterior) horns
•Anterior (ventral) horns

89. Spinal Cord Anatomy
•Central canal filled with cerebrospinal
fluid

90. Spinal Cord Anatomy
•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 –carriers motor information
from the spinal cord

91. Spinal Cord Pathways

92. Spinal Cord Pathways
dorsal columnsrefers to
theposteriorspinal cord
contains ascending
sensory pathways

93. Spinal Cord Pathways

94. Traumatic Brain Injuries
•Concussion
•Slight brain injury
•No permanent brain damage
•Contusion
•Nervous tissue destruction occurs
•Nervous tissue does not regenerate
•Cerebral edema
•Swelling from the inflammatory response
•May compress and kill brain tissue

95. Cerebrovascular Accident (CVA)
•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

96. Alzheimer’s Disease
•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

97. Peripheral Nervous System
•Nerves and ganglia outside the central
nervous system
•Nerve = bundle of neuron fibers
•Neuron fibers are bundled by
connective tissue

98. Structure of a Nerve
•Endoneurium
surrounds each fiber
•Groups of fibers are
bound into fascicles
by perineurium
•Fascicles are bound
together by
epineurium

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

100. Spinal Nerves

101. Spinal Nerves
spinal cord segment
has four roots:
ananterior(ventral)
andposterior(dorsal)
rooton both right and
left sides.
Gray/white ramus –
contains pre/post
ganglionic fibers that
connects to the
sympathetic trunk.

102. Spinal Nerves

103. Spinal Nerves

104. Spinal Nerves

105. Spinal Nerves

106. Cranial Nerves

107. Cranial Nerves
BELL’S PALSY
SignsandsymptomsofBell'spalsycomeon
suddenlyandmayinclude:
Rapidonsetofmildweaknesstototalparalysison
onesideofyourface—occurringwithinhoursto
days
Facialdroopanddifficultymakingfacial
expressions,suchasclosingyoureyeorsmiling
Drooling
Painaroundthejaworinorbehindyourearonthe
affectedside
Increasedsensitivitytosoundontheaffectedside
Headache
Alossoftaste
Changesintheamountoftearsandsalivayou
produce

108. MYOTOME & DERMATOME

109. Autonomic Nervous System
•The involuntary branch of the nervous
system
•Consists of only motor nerves
•Divided into two divisions
•Sympathetic division
•Parasympathetic division

110. Comparison of Somatic and
Autonomic Nervous Systems
Ganglion = synaptic relay stations between neurons

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

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

113. Organization of the Nervous System

114. Development Aspects of the
Nervous System
•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

115. Development Aspects of the
Nervous System
•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!

116. Case Studies
A 62-year-old female with a medical history of hypertension and
hyperlipidemia presented at a primary stroke center after suddenly
experiencing weakness on her right side. During the examination,
she displayed multiple neurological symptoms, including global
aphasia, left gaze preference, right homonymous hemianopsia, right
facial droop, dysarthria, and right hemiplegia. A head CT scan
revealed hypodensity in the left middle cerebral artery area.
Subsequently, a CT angiography confirmed the presence of a left
middle cerebral artery occlusion. Alteplase intravenous tPA treatment
was administered within 2 hours of symptom onset. The patient was
later transferred to a comprehensive stroke center, where digital
subtraction angiography confirmed the occlusion in the left middle
cerebral artery.
Cerebrovascular Accident