Transcript Document

The Nervous System
Two Components
Central Nervous
System
• Brain
o Cerebrum
Frontal Lobe
Parietal Lobe
Temporal Lobe
Occipital Lobe
o Cerebellum
o Medulla
• Spinal Cord
Peripheral Nervous
System
• Nerves
o
movement, senses, etc.
• Neurotransmitters
Cerebrum
• Divided into two hemispheres
• Majority of what is considered "brain"
• Made up of 4 lobes
o Parietal Lobe
o Temporal Lobe
o Frontal Lobe
o Occipital Lobe
• Major functions
o Movement
Conscious movement
Cerebrum cont'd...
o Senses
Processes information from body (smell, sight,
feel, taste, sound)
o Speech
Comprehension
Communication
o Learning and Memory
• Made of nerve cells (grey matter)
• White nerve fibers connect signal from nerve
cells and other parts of brain/ body
Cerebellum
• "little brain"
• Two hemispheres, folded to achieve
more surface area
• regulation and coordination of
voluntary movement
• posture
• balance
Medulla
• Lower portion of brainstem
• Controls involuntary movement
o Heartbeat
o Breathing
o Swallowing
o Vomiting
o Defecation
o Reflexes
Occipital Lobe
http://www.neuroskills.com/tbi/boccipit.shtml
http://www.sci.uidaho.edu/med
532/occipita.htm\
• Function:
o Vision
o Perception
Temporal Lobe
http://www.sci.uidaho.edu/med532/temporal.htm
Function:
• Sense of Hearing
• Aspects of Memory
• Emotional Behavior
Temporal Lobe Epilepsy (TLE)
http://en.wikipedia.org/wiki/Temporal_lobe_epilepsy
• Two Types:
http://www.sci.uidaho.edu/med532/temporal.htm
o Mesial TLE
o Lateral TLE
• Etiologies:
o Relation with febrile seizures (seizures that result from increases in body
temperature, common in infants whose temperature maintenance is immature)
o Generally related to prolonged seizure
• Symptoms:
o Simple Partial Seizures (SPS)
o Complex Partial Seizures (CPS)
o Secondarily Generalized Tonic-Clonic Seizures (SGTCS)
• Treatments
o Medication
 Phenytion, Carbamezepine, Calproate, and Phenobarbital
 Newer drugs, though,
like gabapentin, topiramate,Levetiracetam andlamotrigine, promise
similar efficacy with fewer side-effects.
 Basically such medication functions by decreasing the excitation
of neurons or by enhancing their inhibition
o Excision Surgery
Frontal Lobe Functions
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Motor activity
Speech
Reasoning
Emotions
Problem Solving
Spontaneity
Memory
Language
Initiation
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Judgment
Impulse Control
Social Behavior
Sexual Behavior
Frontal Lobe Fun Facts
• Very vulnerable to injury and the most
common region of injury due to location and
size
• Reaches full maturity around age 25
• Frontal Lobe damage can result in...
o Little spontaneous facial expression
o Difficulty speaking
o Increase or decrease in socialization
o Dramatic decrease in creativity and problem
solving skills
o Mental flexibility and spontaneity impairment
Parietal Lobe Functions
• Processes information about
o Touch
o Taste
o Pressure
o Pain
o Heat/cold
Functions:
• Movement
• Orientation
• Recognition
• Language Processing
Parietal Lobe Fun Facts
• Parietal Lobe is divided into two functional
regions
o One integrates info to form a single
perception
o The other lets the body know where it is in
space in relation to the
world
around it
• Damage to the Parietal Lobe
may
cause
o Neglecting part of the body or
space
(makes it hard to care oneself)
o Inability to perceive objects
Hippocampus
http://www.psycheducation.org/emotion/hippocampus.htm
• part of the limbic system (emotion system of the brain)
o in charge of transferring information into memory
• part of the temporal lobe (inside fold; not visible from outside)
• Necessary for making new memories [Alzheimer's disease
(mentioned later) affects the hippocampus first and severly]
• involved in severe mental illnesses
• Directly affected by estrogen
o estrogen increases "synaptic density" or the number of
connections to other nerve cells
Hypothalamus http://webspace.ship.edu/cgboer/limbicsystem.html
• maintains homeostasis
• regulates hunger, thirst, response to pain, levels of pleasure, sexual
satisfaction, anger, aggresive behavior and more
• regulates functioning of parasympathetic and sympathetic nervous
systems (regulates pulse, blood pressure, breathing,etc.)
• It recieves info from...
o vagus nerve; gives info about blood pressure and how full the
stomach is
o reticular formation of brainstem; gives info about skin temp.
o optic nerve; gives info about light and darkness
o unusual neurons lining the ventricles, it gets info about contents
of the cerebrospinal fluid incluidng toxins that lead to vomiting
o limbic system/olfactor nerves; give info that regulate eating and
sexuality
o it's own receptors; give inof about ion balance and temp of the
blood
Hypothalamus
• Sends instructions by...
o autonomic nervous system
 control of blood pressure, heartrate, breathing, digestion,
sweating, and all sympathetic/parasympathetic functions
o pituitary gland
 neurally and chemically connected to this gland
 gland pumps hormones releasing facors into blood stream
 hormones regulate growth and metabolsim
Amygdala http://thalamus.wustl.edu/course/limbic.html
• FEAR
o couples a learned sensory stimulus (dog snarling = danger) to an
adaptive response (fight or flight)
• Sensory input
o visual
o auditory
o somatosensory cortices (the part of the brain where sensory
signals are sent)
• Outputs
o hypothalamus
o brainstem
• involved in mood and conscious emotional response to an event
• damage (rare)
o no response to fearful events
o inability to recognize fear in the facial expression of others
Spinal Cord
http://faculty.washington.edu/chudler/spinal.html
• Pathway connecting brain + peripheral nervous
system
• Protected by spinal column
( bone )
o made up of 31 segments
8 cervical
12 thoracic
5 lumbar
5 sacral
1 coccygeal
o pair of spinal nerves exit from each segment
Neurons
• Neurons are specialized to carry "messages"
through electrochemical processes
• Like all cells of the body, neurons
o Are surrounded by a cell membrane
o Have a nucleus that contain genes
o Contain cytoplasm, mitochondria, and other
organelles
o Carry out basic cellular processes such as
protein synthesis and energy production
Neurons
• Neurons are different from other cells because...
o They have specialized extensions called
dendrites and axons
o Communicate with each other through
electrochemical processes
o Contain specialized structures (ex. Synapses)
and chemicals (ex. Neurotransmitters)
Anatomy of Neurons
• Dendrites bring info TO the cell body
o Many to a cell
o No myelin insulation
o Branch near cell body
• Axons take info AWAY from cell body
o Generally only one to a cell
o Usually have myelin
o Branch further from cell body
• Myelin Sheath is made of electrically-insulating
material and surrounds the axon of a neuron. The
myelin sheath increases the speed at which
impulses travel along the axon.
Dendrites
Som
a
Axon
Myelin
Sheath
Terminal button
Or terminal end
It’s a neuron!
Impulse Transmission
• A synapse is a small gap separating neurons
o Types of synapses (axodendritic, axosomatic,
axoaxonic)
• In order for neurons to communicate, an
electrical impulse must travel down an axon to
the synaptic terminal (the “bulb” end of an axon)
Impulse Transmission cont.
• At the synaptic terminal, the
electrical impulse will trigger the
release of neurotransmitters into
the space between neurons
• The neurotransmitters then bind
with receptor sites on the
postsynaptic ending (the
membrane on the other neuron)
The binding to receptor sites
influences the electrical response
in the post synaptic neuron
Neurotransmitters
Neurotransmitters can be… excitatory or inhibitory
• Excitatory neurotransmitters increase the probability
of the electrochemical impulse being transmitted to
the adjoining cell
• Inhibitory neurotransmitters decrease this probability
• A balance is necessary…. If a stroke or trauma
damages the tract of inhibitory motor neurons
(neurons not able to inhibit neurotransmitters to other
motor neurons) … result is excessive contractions of
muscles
• Remember: a typical neuron may have many
synaptic connections with the synaptic terminals of
many different axons
Sum Up of Neurons
Brain Abscesses
• What is a brain abscess?
o a mass of immune cells, pus, and other material due
to a bacterial or fungal infection
• What are its etiologies? or causes?
o A bacterial or fungal infection that did not start in the
brain...for example, an ear infection could cause a
brain abscess if the bacteria travels through the blood
(to brain)
most common source is a lung infection
o sometimes parasites
o introduction of infectious organism through
injury (ex. knife wound) or surgery
Brain Abscesses
• Inflammation develops as a result of this infection
• Infected brain cells, white blood cells, and
live/dead microorganisms collect in a limited area
of the brain which may be enclosed by a
membrane
• This immune response is good to isolate the
infection, however...
o The brain swells and the mass may put pressure
on delicate brain tissue
o Infected materials can block vessels of the brain
Brain Abscess Symptoms
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Headache
Stiff or aching neck, shoulder, or back
vomiting
change in mental status (ex. drowsiness, confusion,
instability, slow thought process, coma
seizures
fever and chills
• Decreased sensation
vision changes
• weakness
loss of muscle function • language difficulties
• loss of coordination
Brain Abscess Treatment
Brain Abscesses may be a serious medical emergency...
If pressure in skull becomes high enough it may cause
death
• Medication
o Especially broad spectrum antibiotics that work
against a number of different bacteria
o Anti-fungal medication may be used (if infection is
caused by fungus)
• Surgery (procedure depends on size and depth)
o Opening and draining abscess
o Entire abscess may be removed if small enough and
enclosed in a sac
Brain Abscess Treatment cont.
• Needle Aspiration (for deep abscess)
oInject medication directly into mass
• Diuretics and steroids may be used to
reduce swelling
Traumatic Brain Injury
http://www.ninds.nih.gov/disorders/tbi/tbi.htm
• Sudden trauma to the brain
o head is jolted/ hits an object
o object pierces skull
• Mild cases o Loss of consciousness, headache, confusion,
lightheadedness, dizziness, blurred vision,
ringing in the ears, bad taste in mouth, fatigue,
behavioral changes, trouble with
memory/concentration/thinking
TBI cont'd...
• Severe cases
o Same symptoms as before
o Also, headache that does not go
away, repeated nausea, convulsions, inability
to wake up from sleep, dilation of one or both
pupils, slurred speech, weakness or
numbness, loss of coordination, increased
confusion
TBI cont'd...
• Treatment
o quick medical attention - stabilize the patient to
prevent further injury
o Not much can be done to reverse the initial injury
o Possible neurosurgery to remove hematomas (ruptured
blood vessels)
o Disabilities - problems with thinking, memory, senses,
communication, mental health,
o Coma - unconscious, unarousable, unresponsive,
unaware
o Vegetative state - unconscious, unaware, but periods of
alertness
o Persistent Vegetative state - vegetative state for more
than one month
New Treatment Idea for TBI
http://www.technologyreview.com/blog/editors/22189/
Technology Reviews Nov 2008
• Some of the neural damage that accompanies TBI results from the impact.
However, most occurs over days, weeks, or months later. The impact triggered
a chemical cascade that triggered the inflammation and cell death. Scientists are
trying to come up with treatments that prevent this slow degeneration.
• Instead of targeting neurons, like scientists have in the past to solve the
degeneration problem, scientists are now targeting astroglia (or astrocytes)
o these cells are thought to support neurons
• Eli Gunnarson, of the Karolinska Institute in Sweden, has found red-blood-cell
booster hormone erythropoietin (EPO) protects against swelling by closing a
channel that normally imports water into astroglia
• David Meaney and his colleagues at the University of Pennsylvania, have
found that right after injury, astroglia receive a flood of calcium ions; which is
toxic to neurons. If a drug could be developed that stops the flood by inhibiting
the specific receptor on the cell's surface the degeneration could be stopped (a
class of compounds has already been found to do this)
Other Diseases!
http://www.sci.uidaho.edu/med532/dorsalat.htm
http://www.sci.uidaho.edu/med53
2/alzheimer.htm
• Alzheimer's Disease http://www.sci.uidaho.edu/med53
2/wallenberg.htm
o More common in women
than men
o Caused by atrophy ofhttp://www.sci.uidaho.edu/med53
cerebral cortex and other forebrain
2/wernickes_aphasia.htm
territory
o In some serious cases, the brain can weigh less than 1000 grams
at death.
• Wallenberg Syndrome
o Difficulty swallowing
o Hoarseness
o Caused by paralysis of vocal cords
• Wernicke Aphasia
o Impairment in the comprehension of written and spoken
language
o Inability to speak substantive language
Possible New Treatment for Alzheimer's
http://www.sciencedaily.com/releases/2009/02/090202174818.htm
Science Daily Feb 2009
• Northwestern University research team found that insulin may
slow or prevent damage and memory loss caused by toxic proteins
in Alzheimer's disease, by shielding memory-forming synapses
from harm
• Therapeutics designed to increase insulin sensitivity in the brain
may help treat the disease; sensitivity to insulin decreases with age
(a risk factor for Alzheimer's)
• Sergio T. Ferreira, member of research team, commented,
"Recognizing that Alzheimer's disease is a type of brain diabetes
points the way to novel discoveries that may finally result in
disease-modifying treatments for this devastating disease
So How is the Nervous System Interrelated,
Interconnected, and Interdependent with other systems??
• The Nervous System works very much with the following
systems and organs:
 Skin
 Eyes
 Ears
 Mouth
 Endocrine System
 Muscular System
 Skeletal System
 Circulatory System
 Respiratory System
 Immune System
CAN YOU EXPLAIN HOW??