Transcript Disorders of the Nervous System

Central Nervous System
Most highly organized and complex
system of the body
-Communication and coordination
system of the body
-Seat of intellect and reasoning
-Consists of the brain, spinal cord,
and nerves
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NEURON = Nerve cell
Transmits a message from one neuron to
the next
NEUROGLIA = nerve “glue”, holds nerve
together
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DENDRITES
Nerve cell processes that carry impulse to
the neuron
axon
May be one or many
AXON
Carries impulse away from neuron
Only one on a neuron
dendrites
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NEURILEMMA (MYELIN SHEATH)
Myelin is a fatty substance that protects the
axon
Speeds up the nerve impulse as it travels
along the axon
SYNAPSE – space between neurons,
messages go from one cell to the next
The ends of the dendrites and axons never touch at
the synapse
 So how is the nerve message continued along
the axon/dendrite route???
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The synapse contains
Neurotransmitters
Chemicals which help the message “jump” across
the synapse
 i.e. Dopamine, Epinephrine
Acetylcholine
Endorphins are neurotransmitters produced
in the brain that reduce pain
 They have also been known to induce
euphoria. Drugs such as morphine, heroine
and cocaine are classic endorphin-releasing
entities
 Laughter, chocolate, acupuncture, exercise
trigger an endorphin release
“runner’s high”
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All neurons have 2 characteristics:
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1. irritability: neurons can react when
stimulated
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2. conductivity: neurons can transmit an
impulse to another neuron
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3 Types of Neurons
SENSORY NEURONS (AFFERENT) – emerge from
the skin or sense organs, carry impulses to spinal
cord and brain
MOTOR NEURONS (EFFERENT) – carry
messages from brain and spinal cord to muscles
and glands
INTERNEURONS (ASSOCIATIVE NEURONS)–
carry impulses “in between” sensory neurons and
motor neurons found in the spinal cord
The Brain
 3 lb mass of soft nervous tissue
 100 billion neurons
 Protected by:
-Cranium (craino is root word for skull)
-3 membranes called meninges, and
-cerebrospinal fluid (CSF)
 brain tissue will die in 4-8 mins. without O2
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Coverings of the Brain (MENINGES)
DURA MATER – outer brain covering, lines
the inside of the skull, tough connective
tissue.
ARACHNOID – middle layer, resembles fine
cobweb
PIA MATER – covers the brain’s surface,
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CEREBROSPINAL FLUID – bathes the brain
and spinal cord, liquid shock absorber
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SUBDURAL SPACE – between dura and
arachnoid, contains CSF
SUBARACHNOID SPACE - between
arachnoid and pia mater, filled with CSF
What would a subdural hematoma be???
Bruise on the brain under the dura mater
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Subdural
Hematoma
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Ventricles of the Brain
Brain contains four cavities filled with
cerebrospinal fluid.
Right and left lateral ventricles largest
Third ventricle below R and L ventricles
Fourth ventricle is below the 3rd, extends
into spinal cord
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CHOROID PLEXUS – network of blood vessels
lining the ventricles
forms cerebrospinal fluid
BLOOD-BRAIN BARRIER – choroid plexus
capillaries prevent substances (like antibiotics)
from penetrating brain tissue – this makes
infections difficult to cure i.e. meningitis
HOWEVER
it prevents harmful substances from entering the
brain tissue
Meningitis inflammation of the meninges
 causes excess production of CSF
What type of S/S might you see???
 Headache
 Stiff neck
 What do we do to relieve some of the extra
CSF???
LUMBAR PUNCTURE
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LUMBAR PUNCTURE (spinal tap)– removal
of CSF from spinal canal
needle puncture between 3rd and 4th lumbar
vertebrae
 Why would we place the needle at this
vertebrae??
 Spinal Cord ends at L2
Used to diagnose
 Tumors, meningitis, other infections
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PARTS OF THE BRAIN
CEREBRUM
CEREBELLUM
DIENCEPHALON
BRAIN STEM
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CEREBRUM
Largest part of the brain
Divided into R and L hemispheres
We know that our brain is divided into 2 hemispheres
The L side of the brain controls the R side of the body
and vice versa
If we have a L sided CVA, which side of the body will be
effected???
The R side
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Fissures deep grooves in the brain
They are important because they specify
“functional area”
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Corpus Callosum largest fissure, wide
band of fibers that hold the R and L
hemispheres together
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SULCI – shallow grooves separating
cerebral convolutions
CONVOLUTIONS – elevated ridges that pop
up on the surface of the cerebrum
they increase the surface area of the brain
which increase our “gray matter”
 The more gray matter you have the
SMARTER YOU ARE!!!!
Cerebrum
parietal
Parietal
frontal
Temporal
temporal
occipital
Occipital
Functions of the Cerebrum
Determined by the 4 lobes
All lobes are covered by the cerebral cortex
or gray matter
1. Frontal Lobe - voluntary motor functions
-speech
-emotions/personality
-memory/reasoning/will power
-learning/intellect
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The L frontal lobe holds the center that
allows us to speak
If we have a CVA in that area we may know
WHAT we want to say, but be unable to say it
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2. Parietal Lobe receives and interprets
-pain
-touch
-heat/cold
3. Occipital Lobe controls eyesight
4. Temporal Lobe controls impulses for
-auditory
-smell
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At the junction of the temporal, parietal and
occipital lobes is the area that allows us to
RECOGNIZE and INTERPRET
written and spoken words
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CEREBRAL DOMINANCE
 90-95% of the population is L side dominant
meaning we are R handed
But intellectually, why do we use one side of our
brain more than others…. or do we????
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How does memory work????
P.140
Brain teaser
CEREBELLUM
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2ND largest part of the brain
Looks like the “onion” part at the back of the
brain
Controls all body functions related to
skeletal muscles
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Cerebellum
1. Balance: works with the inner ear, sends messages to
cerebral cortex to restore and maintain balance
2. Muscle tone all muscles have tone
3. Coordination of muscle movements
 makes muscle movements smooth, flowing and
coordinated
 Coordinates complex skills such as walking, talking,
etc.
i.e. Cerebellum coordinates 50 muscles and 30 bones of
the hand and arm to raise your hand and prevent a
blow to your face
DIENCEPHALON
Located in the very middle of the brain
Composed of:
THALAMUS and HYPOTHALAMUS
and 1 gland PITUITARY GLAND
1. Thalamus relay station for impulses going
to the cerebral cortex
2. Hypothalamus “brain of the brain”
 connected to the pituitary gland and tells it when to
release hormones
Hypothalamus has multiple functions:
- controls autonomic nervous system (BP and P)
-maintains body temperature
-appetite control -water balance -sleep control
-intestinal peristalsis/secretions
-makes oxytocin
(causes labor) synthetic form is Pitocin “Pit drip”
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It also is associated with emotional control as
a part of the limbic system
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BRAIN STEM
contains 3 parts:
 Midbrain
 Pons
 Medulla oblongata
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Pons and midbrain serve as relay
pathways for impulses between cerebrum,
cerebellum, spine and body
Brain stem contains the
Reticular formation system
-involves the sleep/wake cycle and if it is damaged,
coma results
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Medulla Oblongata
IT IS THE NUCLEI OF ALL VITAL
FUNCTIONS!!!!
-PULSE -BP
-Rate/depth of respirations
-Swallowing and vomiting
SPINAL CORD
 Continues down from the brain to the 2nd
lumbar vertebrae
 Lies within the spinal column, surrounded by
the meninges and CSF
Functions:
 Reflex center
 Pathway for nerve impulses to and from the
brain
DIVISIONS OF THE NERVOUS
SYSTEM
1. Central Nervous System
brain and spinal column
2. Peripheral Nervous System
“to the side”
Contains the:
a. Autonomic Nervous
System (ANS)
b. Cranial nerves
c. Spinal Nerves
AUTONOMIC NERVOUS SYSTEM
“involuntary”
“automatic”
Controls activities of visceral organs
1. SYMPATHETIC NERVOUS SYSTEM
“fight or flight” system
– when the body perceives danger, SNS sends
message to adrenal gland to secrete
adrenaline aka: epinephrine
So what does Adrenaline do to us???
What does it feel like when you get
“butterflies”
Increase pulse and BP
Decrease blood flow to stomach/intestines
 Dry mouth
 Nausea
 Sweaty
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2. PARASYMPATHETIC NERVOUS
SYSTEM – counters effects of SNS,
 The SNS and PNS
 work as a pair to balance each other
What do we call a constant state of
“fight or flight”???
STRESS!!!!!!!
To much stress hormone (adrenaline)
can cause health problems!
-heart disease,
-increased BP,
-headaches
-digestive problems
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SPINAL NERVES
Originate at spinal cord and go through openings in
vertebrae
31 pairs of spinal nerves
Nerves divide, form a network or “plexus” and
serve a body segment
1.CERVICAL PLEXUS serves the neck and shoulder
Phrenic nerve stimulates diaphragm
2. BRACHIAL PLEXUS serves hands/wrists
RADIAL nerve
Lower 2 sections are sometimes refered to as the “horse's tail”
3. LUMBAR PLEXUS stimulates the anterior hip and thigh, buttocks
FEMORAL NERVE
4. SACRAL PLEXUS stimulates posterior leg/thigh
SCIATIC NERVE largest nerve in the body
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Reflex Act
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simplest type of nerve
response
i.e. blinking your eye
 Every reflex is proceed by a stimulus
 Receptors pick up the stimulus
Response to the stimulus is called a reaction
Most familiar reflex is the knee-jerk reflex
Tap the patella tendon with a percussion hammer
and the knee jerks
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Traumatic Brain Injury
 Concussion: brain is only slightly injured
 Contusion result of severe head injury/trauma
 i.e. a contusion to the brain stem would result in a
coma
What structure has been damaged??
Reticular formation system
-Contracoup injury: brain slams against cranium in
one direction and then back in the other direction
After head trauma/injury, pressures
increases in the cranium due to:
1. cerebral edema swelling in and around the
brain
2. intracranial hemorrhage bleeding in the
cranium
If pressure is not relieved, pressure crushes the
diencephalon and brain stem
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Head trauma can result in:
 1. stupor brief periods of consciousness
 2. coma no consciousness
 3. vegetative state various sleep wake
cycles but no response to stimulus
 4. persistent vegetative state (PVS) a
permanent state of no responsiveness
Glasgow Coma Scale
A scale based on the patient’s ability to respond
to commands
 i.e. open your eyes, respond verbally, move
their limbs
 Ranges from a score 3-15
 The lower the score, the more severe the
head injury
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Examples of brain trauma/injury:
 subdural hematoma: bruise between the
dura mater and arachnoid layers
 Subarachnoid hematoma bruise between
the arachnoid layer and pia mater
 CVA
 Aneurysms (causes intracranial bleeding)
 Blunt trauma
MENINGITIS
 Inflammation of the meninges of the brain
and spinal cord
 Symptoms – headache, fever and stiff neck
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How would this be diagnosed???
LP
May be bacterial or viral
If bacterial, may be treated with antibiotics
ENCEPHALITIS (encephal is root word for inside
the brain)
 Inflammation of the brain
EPILEPSY
 Seizure disorder,
 characterized by recurring and excessive
discharge from neurons “pinball”
 Cause – uncertain, multiple
 Grand mal – severe, convulsive seizure
 Petit mal – milder, may appear to be daydreaming
 Treatment anticonvulsants
Care for a Person who is seizing
 Get them on the floor
 DO NOT TRY TO PUT ANYTHING IN THE
THEIR MOUTHS!!!
 Gently cradle their heads and turn it to the
side
 DO NOT TRY TO HOLD THEM DOWN
 After seizure is over, allow them to rest
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CEREBRAL PALSY
 Disturbance in voluntary muscular action
due to brain damage, birth trauma,
abnormal brain development
 Symps – head rolling, grimacing, difficult
speech and swallowing, spastic paralysis in
limbs
 No impairment of intellect
POLIOMYELITIS (viral)
 Disease of nerve pathways of spinal cord – causing
paralysis
 Almost eliminated in USA (vaccine)
HYDROCEPHALUS
 Increase of cerebrospinal fluid within ventricles
 Causes enlargement of head, usually noticed at birth
 Can be caused by trauma
 Bypass or shunt performed to relieve pressure
PARKINSON’S DISEASE
 Symps – tremors, shuffling gait, pill-rolling,
and muscular rigidity
 Decrease in neurotransmitters
probably dopamine
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Rx –drugs to treat symptoms
MULTIPLE SCLEROSIS (MS)
 Immune cells attack myelin sheath of axon
 What does the myelin sheath do???
 Transmission of nerve impulses blocked or lost
 Cause – unknown
 Symps – weakness of extremities, loss of
coordination, double vision,
 mostly women, age 20 – 40,
 Rx –drugs to slow progression
DEMENTIA
 Loss of 2 areas of complex behavior
i.e. language, memory, visual abilities, or judgment
 ALZHEIMER’S DISEASE
 Progressive disease that begins with problems
remembering
 Cerebral cortex degenerates, neurons become
tangled
 Cause – unknown
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First stage (2-4 years) confusion, short-term
memory loss, poor judgment
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2nd stage (2-10 years) difficulty recognizing
people, motor problems, and loss of social skills
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3rd stage (1-3 years) inability to recognize
oneself, weight loss and aphasia( inability to
speak)
NEURALGIA pain along a nerve
NEURITIS: inflammation of a nerve
PARESTHESIA tingling, burning, and crawling of
skin
1. Sciatica neuritis of the sciatic nerve
pain radiates down the back of the leg
2. Trigeminal Neuralgia neuritis of the
Trigeminal nerve,
3. Bell’s Palsy involves the facial nerve,
eyes may not close properly, mouth may droop
4. SHINGLES herpes zoster
 Same virus as chicken pox, it goes dormant
and lies on the spinal nerves
 Reappears along the back
 Causes severe itching and pain
 Generally seen in older adults
Cerebral Vascular Accident “Stroke” CVA
Interruption of blood and O2 to brain
causing tissue death
 Risk Factors: same as for MI
 Causes of CVA
-90% caused by blood clots lodged in
carotid arteries
-ruptured blood vessels in the brain
“brain bleed”
Symptoms
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Hemiplegia paralysis on one side of the
body, opposite side of the
body
Sudden, severe headache, dizziness
Sudden loss of vision in one eye
Aphasia, Dysphasia (swallowing)
Coma, possible death
Treatment
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Get to the hospital immediately!!
If a clot, treatment aimed at dissolving
clot
What would we use???
Prevention is the best treatment
one aspirin a day
TIA’s “mini strokes” transient ischemic attacks
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PARALYSIS – loss of power of motion or
sensation
PARAPLEGIA – paralysis in lower
extremities, seen in spinal cord injuries
QUADRIPLEGIA – paralysis all four
extremities, also seen in spinal cord injuries
Diagnostic Tests
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ELECTROENCEPHALOGRAM (EEG) - recording
of the electrical activity of the brain
CAT SCAN – (Computerized Axial Tomography)
Combines X-ray emission with nuclear medicine
MRI – Magnetic Resonance Imaging – uses a
magnetic field along with radio frequency to produce
cross-section images of the body. Patient inserted
into chamber built within a huge magnet
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Eyes in relation to the brain