Transcript Brain Structure and Function

The Nervous System
By: Jen Pote and Megan Gallagan
Major Divisions of Brain
• Cerebrum
– Outer layer of gray matter
– Neuronal cell bodies, dendrites
– Higher functions (language, abstract
thought)
• Cerebellum
– Attached to brain stem, part of hindbrain
– Fine motor coordination/body movement,
posture, and balance
• Medulla (brain stem)
– Part of hindbrain
– Controls heart rate, constriction/dilation of
blood vessels, respiration, and digestion
Functional Lobes of
Cerebrum
• Occipital:
• Responsible for receiving/processing
VISUAL info.
• Temporal: Responsible for processing
AUDITORY signals
• Parietal: Processes information about
touch, taste, pressure, pain, cold, and
heat
• Frontal: Responsible for motor activity,
speech, and thought processes
The Neuron
• Humans have about 100 billion neurons
in their brain
• Neurons have three main parts:
– Dendrites (short, highly branched fibers that
receive information from another cell and
pass it on to the cell body)
– Cell body (contains nucleus, mitochondria,
cytoplasm, and organelles)
– Axon (long fibers that conduct messages
away from the cell body)
The Neuron
Types of Neurons
• Motor Neurons
– Transmit messages FROM central nervous system TO
muscles/glands
• i.e. brain sends message to hand to touch desk
• Sensory Neurons:
– Carry messages FROM sensory receptors TO the central
nervous system
• i.e. hand feels desk sends message to brain which
recognizes what is being touched and what it feels like. “this
is a desk!”
• Interneurons
– connect neuron to neuron
• Like the game Telephone. Neurons must pass the message to other
neurons that eventually get the message to the desired destination
Nervous Tissue
• Neurons- transmit nerve messages
• Glial Cells- Serve as support cells and help
protect neurons
• Astrocytes- type of Glial cell. Provides
support for the endothelial cells, provide
nutrients to the nervous tissue, maintains
balance of ions, and helps with the
repairing and scarring process after brain
and spinal cord injuries
Nerves
• A nerve is an
enclosed cable-like
bundle of axons.
• Provide common
pathways for nerve
impulse
transmissions
Impulse Transmission
• When neurons are at rest (not transmitting messages)
they maintain a “resting membrane potential”
- This is when the cytoplasmic fluid next to the membrane
is negatively charged and the interstitial fluid outside
the membrane is positive.
• When a message needs to be sent signals are sent to the
dendrite and the neuron is stimulated by “action
potential”
- A brief voltage reversal across the plasma membrane
• When the voltage in that area of the neuron reaches a
threshold level the action potential triggers the voltage
reversal along the rest of the neuron. This creates a
chain reaction: dendrite>cell body>axon>dendrite of the
adjacent neuron
Head Injury
• Head injury-injury that can occur to the
scalp, skull, brain, and underlying tissue
and blood vessels in the head.
• Brain Injury- injury that disrupts the
function of the brain
– Can be caused by a blow, jolt, or penetration
to the head
– Can be mild to severe
– Can result in short term problems or long term
problems
Types of Head Injury
1.
2.
3.
Concussion- injury to the head that can cause instant loss of
awareness or alertness. The concussion is temporary but may
result in permanent damage
Skull fracture- a break in the skull bone. Four major types:
1. Linear-break but does not move bone.
2. Depressed-part of skull is sunken in
3. Diastatic- fracture that occurs along areas between the
bones
4. Basilar-most serious type. Break in the bone at the base of
the skull.
Intracranial hematoma- blood clots in or around the brain
Jeffrey’s Story
• My Uncle Jeff- in 1967 while he was riding his
bike he was hit head on by a car. His brain
stem (Medulla) was damaged, his jaw
shattered, and he went immediately into a deep
coma
– Coma: a profound state of unconsciousness. Person
cannot be awakened and does not respond to pain,
light, or sound.
Jeffrey’s Story
• Jeff was in a coma for four months with no response
• Doctors said he would die and if by some chance he survived he
would be a vegetable
• While in the coma they put him in ice water mats to keep body
temperature low and to make sure the brain didn’t swell
• Jeff was not really moved around contrary to today’s treatment
where patient’s muscles are moved to prevent atrophy
• Four months later Jeff awoke and entered into a semi-coma
– He was responsive: blinked once for yes, etc. could not talk
– Fell in and out of consciousness
– Recognized family, etc.
– Could not sit up or move
Jeffrey’s Story
• Once in semi-coma he was moved to a rehabilitation hospital
• Jeff remembered certain information such as his best friend’s
phone number
• Had to re-learn how to talk, eat, and sit up. But it came back
quickly
• Had to build up muscle again
• Speech therapy-Jeff’s speech was permanently damaged
• When Jeff’s brain stem was injured the messages that are sent
from his brain to his body telling it to move were damaged.
Today Jeff does not have control over his legs or his left arm.
Common Diseases of the Brain
• Alzheimer's
• Cause is still unknown
• Formation of round senile plaques
• Causes loss of memory and inability to carry out
daily procedures such as dressing or eating
• Increases rapidly. Lifespan with disease is usually
5 years
Common Diseases of the Brain
• Parkinson’s
– Movement disorder that occurs when brain cells that
make the neurotransmitter Dopamine die over time
– Symptoms: shaking, slow movement, freezing in
place, soft voice, difficulty with facial expression, and
stiff limbs
– Treatment: medication to replace Dopamine loss
Common Diseases of the Brain
• Stroke
– Blood flow is interrupted by a clot. Oxygen
and nutrient flow is cut off
– Causes brain cells to die
– Treatment: preventative “clot busting” drugs
Common Diseases of the Brain
• Depression
– Medical disorder in which sadness persists and interferes with
day to day activities
– Symptoms: loss of energy and enthusiasm, inability to
concentrate, changes in sleep patterns and appetite, memory
loss, crying spells, social withdrawal, physical pains and
sometimes suicidal thoughts
– Treatments: therapy and drugs
Brain Abscesses
• A collection of immune cells, pus, and other materials in
the brain, usually caused by a bacterial or fungal
infection
• Inflammation response to infection: immune response
• Even though immune responses are meant to help the
body, it can also be harmful to the body because as
abscesses are formed, the brain swells and since the
skull is unable to expand, pressure is put on the brain
tissue, and infected material can block the blood vessels
of the brain
Spinal Cord
• A long, thin, tubular bundle of nervous tissue and
support cells extending from the brain
• Protected by bones which make up the vertebral column
• Surrounded by Cerebral Spinal Fluid, which acts as a
cushion to protect nerve tissues
• Spinal nerve runs through the entire spinal cord and
corresponds with respective areas of the body (the top
controls sensation in the upper body)
• Damage to spinal cord can cause paralysis and loss of
sensation
Breakthroughs-Gene
Therapy
• Doctor Patrick Aubourg (from
France) was able to recognize the
gene that was effected by a fatal
neurological disease called ALD
• Recently, using gene therapy he was
also able remove the damaged gene,
repair it, and re-insert the gene
into patients during the early
stages of ALD
Memory
• Short term- located in the prefrontal lobe. (I ate macaroni and
cheese yesterday)
• Long term-located in the inner fold
of the temporal lobe
(when I was five years old I ate
macaroni and cheese every day)
Brain Fact
• The left side of
our brain
controls the right
side of our body
• The right side of
our bran controls
the left side of
our body
Sources
1.
http://thebrain.mcgill.ca/
2.
http://www.bio.davidson.edu/courses/anphys/2000/Rigel/Impulse%20Trans
mission%202.htm
3.
http://www.biausa.org/aboutbi.htmhttp://
4.
www.healthsystem.virginia.edu/uvahealth/adult_neuro/headinj.cfm
5.
http://www.umm.edu/ency/article/000783.htm
6.
http://www.apparelyzed.com/spinalcord.html
7.
http://www.npr.org/templates/story/story.php?storyId=120118988