Transcript ST110 Nervous System_BB

ST110
Concorde Career College,
Portland
 Define
the term nerve.
 Identify the divisions of the nervous
system.
 Describe the functions of the nervous
system.
 List
and identify the structures of the
nervous system and describe the
function of each.
 Identify the types of nervous tissue.
 Understand the physiology of a nerve
impulse.
 Describe
the mechanism by which
the nervous system helps to maintain
homeostasis.
 Describe common diseases,
disorders, and conditions of the
nervous system including signs and
symptoms, diagnosis, and available
treatment options.
 Demonstrate
knowledge of medical
terminology related to the nervous
system verbally and in the written form.
A nerve is a bundle or a group of bundles
of nerve fibers outside the central
nervous system which connects the brain
and spinal cord with the various parts of
the body.
 Brain
and spinal cord
 Control center for the whole system
 All body sensations and changes in the
environment are relayed to the CNS
 All responses are generated by the CNS
 All
the nerves that connect the brain and
spinal cord with sensory receptors,
muscles and glands
• Afferent or sensory neurons
 Convey information from the outside of the nervous
system to the brain and spinal cord
• Efferent or motor neurons
 Convey information from the brain and spinal cord to
muscles, organs, and glands
 12
pairs
 Need to know
•
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Name
Number
Function
Type (sensory, motor, or mixed)
First (I) Cranial Nerve
Olfactory
 Sensory
 Carries
smell impulses from receptors in
the nasal mucosa to the brain
Second (II) Cranial Nerve
Optic
 Sensory
 Carries
visual impulses from the eye to
the brain
Third (III) Cranial Nerve
Oculomotor
 Mostly
motor; partly sensory
 Movement of the eyeball, eyelid, and
pupil constriction (motor)
 Proprioception (sensory)
Fourth (IV) Cranial Nerve
Trochlear
 Mostly
motor; partly sensory
 Movement of the eyeball - superior
oblique (motor)
 Proprioception (sensory)
Fifth (V) Cranial Nerve
Trigeminal
 Mixed
 Three
divisions
1. Ophthalmic - Skin sensation above the orbit (sensory)
2. Maxillary - Skin sensation from orbit to mouth
(sensory)
3. Mandibular - Sensation of the anterior tongue, lower
teeth, and cheek (sensory) and chewing (motor)
Sixth (VI) Cranial Nerve
Abducens
 Mostly
motor; partly sensory
 Movement of the eyeball - lateral rectus
(motor)
 Proprioception (sensory)
Seventh (VII) Cranial Nerve
Facial
 Mixed
 Proprioception
and taste (sensory)
 Facial expression, tear and saliva
production (motor)
Eighth (VIII) Cranial Nerve
Vestibulocochlear
 Sensory
 Hearing
and balance
 Also known as the auditory or acoustic
nerve
Ninth (IX) Cranial Nerve
Glossopharyngeal
 Mixed
 Blood
pressure regulation, taste,
proprioception (sensory)
 Saliva production (motor)
Tenth (X) Cranial Nerve
Vagus
 Mixed
 Visceral
sensation and proprioception
(sensory)
 Smooth muscle contraction/relaxation
and production of digestive fluids
 Longest cranial nerve “wanderer”
Eleventh (XI) Cranial Nerve
(Spinal) Accessory
 Mostly
motor; partly sensory
 Proprioception (sensory)
 Swallowing and movement of the head
and neck (motor)
Twelfth (XII) Cranial Nerve
Hypoglossal
 Mostly
motor; partly sensory
 Proprioception (sensory)
 Movement of the tongue (motor)
 http://www.wisc-
online.com/objects/ViewObject.aspx?ID
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 Conducts
impulses from the brain and
spinal cord to skeletal muscle
 Sensory and motor neurons
ANS
 Internal
organ control via glands, smooth
and cardiac muscle
 Maintenance of HB rate, breathing, blood
flow
 Sympathetic
 Parasympathetic
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Conducts impulses from the brain and spinal
cord to smooth and cardiac muscle tissue
Involuntary
• Sympathetic Division (emergency situations,
stress, emotions)
 Stimulates or speeds up activity
 Epinephrine/norepinephrine
• Parasympathetic Division
 Slows down many activities
 Adrenocortical hormone (ACH)
The nervous system acts as the “Control
Center” by directing functions of the
body’s organs.
1. Receive stimuli (internal or external)
2. Interpret stimuli
3. Reacts to stimuli
Nerve Cells or Neurons
 Functional cells of the nervous system
 Transmit information via impulses
• Dendrites conduct impulses to the cell body
• Axons conduct impulses away from the cell body
 Nerve
• Bundle (fascicle) of nerve cells

Cytoplasmic extentions  Dendrite:
 receives information
 Cells may have several, one or none
 Typically short and branched
 Axon:
 Transmits impulses away
 Cell has only one
 Long
 Surrounded by a thin wrapping of fiberous connective
tissue called endoneurium
 Branch at their ends – Axon Terminals
 Make contact with dendrites of other neurons
Neuron Classification
 Multipolar
• Several dendrites and one axon
• Schwann cells (neurolemmocytes) surround the axon
to form myelin sheath
• Nodes of Ranvier
 Bipolar
Neurons
• One dendrite and one axon
 Unipolar
Neurons
• Axon extends directly from the cell body
 Sensory (afferent) neurons
• Receive first impulses from receptors
• Unipolar
• Impulse is conducted toward brain or spinal
cord
 Internuncial (association) neurons
• Multipolar
• Brain and spinal cord
• Transmit impulses to appropriate area
 Motor
(efferent)
• Final nerve cell
• Multipolar
• Impulse is conducted away from brain or spinal
cord
• Brings reaction to stimulus

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Myelin= A soft, white, fatty material wrapped around the
membrane of Schwann cells, the substance of the myelin
sheath.
Neurilemma=outer cover
Insulating material that covers axon of neuron
 Similar to plastic around electrical wire
 Gives nerves there white appearance
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Made up of Schwann Cells (neurolemmocytes)
Nodes of Ranvier: Gaps on myelin sheath
 Gaps allow substances (needed for energy) to flow from extracellular
fluid to axons

Capable of regeneration. Not found in brain or spinal cord.

Insulate, support, and protect neurons
 Do not conduct nerve impulses
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Schwann Cells
Astrocytes:
 Star shaped
 Glial cells that attach to small blood vessels to form the
BBB

Oligodendrocytes:
 Support
• Produce fatty sheath of myelin that protects many neurons
of the central nervous system

Microglial cells:
 Protect neurons (phagocytosis)
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Ependymal Cells:
 Line ventricles and produce CSF
 Area
between the terminal branches of an
Axon and the ends of a branched Dendrite
 Synapse= where impulses are transmitted
from one neuron to another
 Axons and Dendrites never actually touch.
Nerve signals “jump” the space between
the two called the synaptic cleft (space
between the synaptic knob and the plasma
membrane of the postsynaptic neuron)
 How do nerve signals jump?
Neurotransmitters
 Neurotransmitters: chemical
messengers,
found in synaptic knobs
• Acetycholine
• Epinephrine (autonomic)
• Dopamine
• Seratonin
• Endorphins (function as natural pain killers)
• Enkephalins
 Involuntary
 Reflex
Arc
reaction
 Involuntary
reaction to an external
response
 Two
neuron and three neuron arcs
 Only
allow impulse conduction in one
direction
 The
dendrites of the sensory neuron pick up
a signal and send it to the cell body in the
ganglion.
 The
axon of the sensory neuron travels from
the cell body and ends near the dendrites of
a motor neuron.
 The
signal jumps the synapse and is sent
down the dendrites to the cell body and to
the axon of the motor neuron to the
“effectors” organ
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3 Neuron Reflex

The sensory neuron’s axon synapses with
the dendrites of the interneuron
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The signal is sent down the interneuron to
the dendrites of the motor neuron
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The “withdrawal” reflex occurs
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All interneurons lie within the gray matter of
the brain and spinal cord
 White
Matter
• Myelinated axons
 Gray
Matter
• Nerve cell bodies and dendrites
 CNS
• Nuclei
• Tracts
 PNS
• Ganglia
• Nerves
White and Gray
Matter
A
group of peripheral nerve fibers/one or
more bundles of neurons
 Each
axon is surrounded by endoneurium
 Wrapped
 Fascicles
 The
axons are grouped fascicles
are surround by perineurium
whole nerve is covered by epineurium
 A self-propagating wave of electrical disturbance
 Must be initiated by a stimulus
 Resting neurons have a slight positive charge on
the outside and a slight negative charge on the
inside
 When
the membrane is stimulated,
sodium rushes in causing a reverse of the
charges
 If
the membrane is covered in myelin, the
impulse jumps in what is called saltatory
conduction
 Resting
or membrane potential
• Na (sodium) ions greater outside
• K (potassium) ions greater inside
• Cl (chlorine)
 Depolarization
or action potential
 Repolarization (return to resting state)
 All-or-none law
Watch the Animation
 Brainstem
• Medulla oblongata
• Pons Varolii
• Midbrain
 Diencephalon
• Thalamus
• Hypothalamus
 Cerebrum
 Cerebellum
 Ventricles
(4)
 Cerebrospinal fluid (CSF)
• Choroid Plexus
 Meninges
(coverings)
• Dura mater (outermost)
• Arachnoid mater (middle)
• Pia mater (innermost)
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Protective tissues that surround the brain and
spinal cord
Subarachniod space contains cerebrospinal fluid
Dura (outermost)
 Tough fibrous connective tissue
 Does not attach directly to the vertebrae. Space between
vertebra and dura is termed Epidural space
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Arachnoid
 Thin, weblike

Pia (innermost)
 Space between the arachnoid and pia layers is termed
the subarachnoid space
 Medulla oblongata
• Connects brain to spinal cord
• Ascending and descending tracts
• Decussation (crossing) of pyramids
• Reticular formation
 Consciousness and arousal
• Reflex centers
 Vasomotor center
 Cardiac center
 Medullary rhymicity area
 Pons Varolii
• Connects spinal cord with the brain
• Help control breathing
 Midbrain (mesencephalon)
• Ventral Cerebral peduncles
 Convey impulses to the pons and spinal cord
 Visual and auditory responses
• Dorsal tectum
 Controls the movement of the eyeballs and head in
response to visual stimuli
 Between
two cerebral hemispheres
 Thalamus
• Main relay station for sensory impulses to cerebral
cortex from spinal cord
• Interpretation center for pain recognition
 Hypothalamus
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Homeostasis
Controls ANS
Controls pituitary
Mind control, rage, thirst, maintains waking state,
sleep, food intake
 Bulk
of the brain
 Cerebral Cortex
 Cerebral Hemispheres
• Longitudinal fissure
• Gyri (prominence)
• Sulci (groove or furrow)
• Corpus callosum (commissure of nerve fibers
between hemispheres)
 Right
Hemisphere:
• Nonverbal, intuitive behaviors
 Left
Hemisphere:
• Speech, computational, analytical skills
• The two hemispheres are connected at the lower
midpoint by the corpus callosum
 What
hemisphere dominates you?
 Frontal
lobe
• Anterior, controls voluntary muscle functions,
moods, aggression, smell reception and
motivation
 Parietal
lobe
• Behind frontal behind central sulcus
• Evaluates sensory info of touch, pain, balance,
taste, and temperature
 Temporal
lobe
• Beneath frontal and parietal separated by lateral
fissure
• Evaluates hearing input and smell
• Some memory processes
• Abstract thoughts and judgment decisions
 Occipital
lobe
• Back portion
• Receives and interprets visual input
 Beneath
the occipital lobes and behind
the pons and medulla
 Coordinates complex skeletal muscle
movements, maintains body posture,
body balance
 Optic Tracts
and Optic Chiasma
• Nerves cross
• Pituitary Gland and mamillary bodies
 Memory and emotional response to odor
• Pineal gland
 Affects moods and behavior
 Carotid
artery
 Anterior
cerebral
artery
 Middle
cerebral
artery
 Median
anterior
spinal artery
Circle of Willis
 Smell
(Olfaction)
 Taste
• Tongue anatomy
 Sight
• Eye anatomy
 Hearing
and Equilibrium
• Inner and outer ear
 Drug
Use
• Depressants
 Valium
 Codeine
 Heroine
 Marijuana
 Hashish
 Stimulants
• Cocaine
• LSD
• Amphetamines
 Alzheimer’s
disease
 Amyotrophic lateral sclerosis
 Anencephaly
 Bell’s palsy
 Brain abscess
 Carpal tunnel syndrome
Amyotrophic
Lateral Sclerosis
(ALS)
Lou Gehrig
Disease
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Lack of brain except for a
rudimentary brainstem
and absence of overlying
skull.
Due to a failure of closure
of the anterior neural tube
- a neural tube defect.
These infants rarely live
past a month of age. May
be candidates for organ
donation.
 Cerebral
contusion
 Cerebral palsy
 Cerebrovascular accident
 Concussion
 Degenerative disk disease
 Encephalitis
 Epilepsy
• Grand mal seizure
• Petit mal seizure
coup/contrecoup
(acceleration/
deceleration)
MRI of a brain with
the area of a
“bleed” visible in
the lower right
 Guillain-Barré
syndrome
 Cephalalgia
 Migraine
headache
 Cluster headache
 Tension headache
 Hematoma
• Epidural
• subdural
 Acute
inflammatory demyelinating
polyneuropathy
 Rapid
onset of weakness and, often, paralysis of
the legs, arms, breathing muscles and face
(may require the use of a ventilator)
 The
majority of patients eventually return to a
normal or near normal lifestyle
 Herniated
Disk
 Huntington’s chorea
 Hydrocephalus
 Intracranial tumors
 Primary intracranial tumors
• Gliomas
 Metastatic
intracranial tumors
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Often appears as facial twitching or as twitching and
writhing of the distal extremities (choreic movements).
Fast eye movements are impaired.
As HD disease progresses, the movement disorder
becomes more generalized. Eventually, the patient's
gait is impaired.
Rigidity and dystonia predominate in later stages of the
disease in adults. In juvenile cases, rigidity and
dystonia may appear as the initial symptoms.
Symptoms become worse with anxiety or stress.
A mental status examination may reveal depression.
Impaired cognitive abilities may be detected on
physical examination.
MRI of brain - Tumor
is visible in the
upper left (frontal)
region
 Meningitis
 Multiple
Sclerosis
 Myasthenia gravis
 Neuroblastoma
 Parkinson’s Disease
 Peripheral neuritis
 Poliomyelitis
Multiple Sclerosis (MS)
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Chronic disease of the central nervous system.
Viral and autoimmune etiologies are postulated. Genetic
and environmental factors are known to contribute to MS,
but a specific cause for this disease is not identified.
Pathologically, MS is characterized by the presence of areas
of demyelination.
Early symptoms may include numbness and/or paresthesia,
mono- or paraparesis, double vision, optic neuritis, ataxia
(loss of balance), and bladder control problems.
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Most common primary disorder of neuromuscular
transmission.
Usual cause is an acquired immunological abnormality, but
some cases result from genetic abnormalities at the
neuromuscular junction.
Patients with myasthenia gravis come to the physician
complaining of specific muscle weakness and not of
generalized fatigue. Ocular motor disturbances, ptosis or
diplopia, are the initial symptom of myasthenia gravis in twothirds of patients; almost all had both symptoms within 2 years.
Oropharyngeal muscle weakness, difficulty chewing,
swallowing, or talking, is the initial symptom in one-sixth of
patients, and limb weakness in only 10%. Initial weakness is
rarely limited to single muscle groups such as neck or finger
extensors or hip flexors.
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Motor system disorder that results in the loss of dopamineproducing brain cells. Dopamine is a chemical messenger
responsible for transmitting signals within the brain.
Occurs when certain nerve cells, or neurons, die or become
impaired. Normally, these neurons produce dopamine. Loss of
dopamine causes the nerve cells to fire out of control, leaving
patients unable to direct or control their movement in a normal
manner.
Four primary symptoms of Parkinson's are tremor or trembling in
hands, arms, legs, jaw, and face; rigidity or stiffness of the limbs
and trunk; bradykinesia, or slowness of movement; and postural
instability or impaired balance and coordination. Patients may
also have difficulty walking, talking, or completing other simple
tasks.
 Poliomyelitis
is an acute viral infection that
involves the gastrointestinal tract and,
occasionally, the central nervous system.
 It is acquired by fecal-oral transmission.
 Clinical manifestations of poliovirus infection
range from asymptomatic (the majority of
infections) to symptomatic, including acute
flaccid paralysis of a single limb to
quadriplegia, respiratory failure, and, rarely,
death.
 Reye’s
Syndrome
 Spina bifida cystica
 Meningocele
 Meningomyelocele
 Spina bifida occulta
 Spinal cord injuries
 Involves
brain damage (encephalopathy)
and liver damage of an unknown cause. It
is associated with the use of aspirin in
children to treat chickenpox or influenza.
 Paraplegia
 Quadriplegia
 Tay-Sachs
Disease
 Trigeminal neuralgia


Fatal genetic disorder in children of European Jewish origin
that causes progressive destruction of the central nervous
system.
Caused by the absence of a vital enzyme called
hexosaminidase A (Hex-A). Without Hex-A, a fatty substance or
lipid called GM2 ganglioside accumulates abnormally in
cells, especially in the nerve cells of the brain. This ongoing
accumulation causes progressive damage to the cells. The
destructive process begins in the fetus early in pregnancy,
although the disease is not clinically apparent until the child
is several months old. Children with TSD die early in
childhood, usually by the age of five.