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The Brain and Nervous System Reference Packet
Cerebellum
Functions
Coordination of voluntary motor movement, balance, muscle tone
Helps provide coordinated movements
Integrates and passes sensory/ motor movements to and from the brain.
Makes sure that all skeletal muscles work together to produce smooth and coordinated
movement
Necessary for learning new motor skills
The size of the cerebellum indicates the physical capability of a person
The cerebellum controls movement by collecting sensory nerve inputs, such as limb
position, balance information and vision, and synthesizing them together to control
movement by sending nerve transmissions down motor nerve outputs.
The learning of physical tasks is done by trial and error and then stored into cerebellar memory.
This is the reason that we never forget certain skills such as riding a bike.
Location
Just above the brain stem, toward the back of the brain
Well protected compared to frontal lobe and brain stem
Separated from the brain stem by the fourth ventricle
Has two portions separated by a narrow median
The surface of each hemisphere is made up of grey matter surrounding a large mass of white
matter (nerve cells with myelinated axons). The whole structure is connected to the rest of the
central nervous system by three very broad tracts of white matter called the cerebellar peduncles,
which connect to the pons, the restiform body which connects to the medulla.
Neurons of the cerebellar cortex are distributed into three layers.
o Molecular Layer: most external, crest shape, and elaborates information.
o Intermediate Layer: made up of Purkinje cells which carry information
relative to the movements of the body to the outside of the cerebellum
o The Granular Layer: most inner layer, granular and Golgi cells-filter
incoming information.
Cerebral Palsy
Occurs because of damage done to cerebellum during birth
Oxygen supply is disrupted-oxygen gets to the brain through the blood. Therefore
when blood flow is disrupted, oxygen cannot get to the brain tissue
A reason for low blood/oxygen flow is because of the umbilical cord being
wrapped around the baby’s neck
There is permanent damage to the brain and loss of synergistic control over
skeletal muscles
Body motions are extremely jerky and simple movements may take more then one
attempt
o Abnormal movements (twisting, jerking, or writhing) of the hands, feet,
arms, or legs while awake, which gets worse during periods of stress
o Tremors
o Unsteady gait
o Loss of coordination
o Floppy muscles
Fun Facts
From birth age until age 2, the cerebellum grows faster than the rate of the brain.
Is almost like a mini brain. “Memories of work” – gradually learned movements.
“Data bank” – daily movements.
Rapid impulses produced by cerebral cortex can elaborate data in less then 1/10 of
a second.
Medulla Oblongata
Structure:
Located at the bottom of the brainstem; between the spinal cord and the pons.
Connects the brain and the spinal cord
Only 3cm long
Function:
Controls and regulates numerous visceral organs
Allows nerve signals to move from the brain to the spinal cord
o Contains tracts of communication that ascend and descend throughout the
nervous system such as the vagus nerve
One of two cranial nerves
This nerve sends signals to many visceral organs from the brain
and sends information to the brain about what the body is doing
Helps regulate heartbeat, breathing, muscle movement, and
digestion
Medulla is stimulated when there is a disturbance in homeostasis
Regulates breathing
o When your oxygen levels are low, your muscles produce lactic acid,
which lowers the pH. The medulla recognizes this acidity and sends
signals to the diaphragm and chest muscles so more oxygen can be
consumed. High CO2 levels will also cause this stimulation of the
medulla. The medulla makes sure that your oxygen levels remain
controlled.
Regulates blood pressure
o Regulates the diameter of arterioles (small arteries) thus adjusting blood
flow by sending impulses through spinal nerves and into the muscles of
the arteries
Regulates heartbeat
o The vagus nerve is used to slow the heartbeat down while the accelerans
nerve is used to speed it up. They are activated by stress, physical activity,
and respiration changes.
o vaso-vagal response (a faint or coma) when the medulla is stimulated too
much and slows down the heart
Contains reflex centers for vomiting, coughing, sneezing, hiccupping, and
swallowing
Damage to the medulla oblongata can result in the need for a ventilator or other
supportive equipment to keep the body working.
o This is because it controls organs required to live (lungs & heart)
o Head injuries and a variety of drugs and medications can cause this
damage (ex. opiates and alcohol)
Cerebrum
Structure
The cerebrum is also known as the telencephalon constitutes the forebrain, along
with diencephalon.
Telencephalon refers to the embryonic structure, from which the fully developed
or mature cerebrum develops.
The cerebrum is divided into symmetric left and right cerebral hemispheres.
The left side hemisphere controls the right side of the body.
The right side hemisphere controls the left side of the body.
The cerebrum is composed of the cerebral cortex (cortices), basal ganglia (basal
nuclei), and Limbic system.
The cerebrum lies in the front or top of the brainstem and in humans is the largest
and well-developed of the five major divisions of the brain.
In large mammals, the cerebral cortex is folded into many gyri and sulci or raised
ridges of the cerebrum and small grooves and trenches of the cerebrum.
Functions
In humans, the cerebrum surrounds older parts of the brain. Limbic (a system in
the brain involving neural structures that take part in emotional behaviors),
olfactory (they system of the brain that is used in the sense of smell), and motor
systems (systems having to do with movement project fibers from the cerebrum to
the brainstem and spinal cord.
The neural networks of the cerebrum facilitate behaviors such as social
interactions, learning, working memory, and speech and language.
The cerebrum directs the conscious or volitional motor functions of the body.
The cerebrum also has primary sensory areas of the cerebral cortex that receive
and process visual, auditory, somatosensory (having to do with touch,
temperature, body position, and nociception or pain.), gustatory (ability to detect
flavor of food and other substances and poisons), and olfactory information.
Damage to the olfactory bulb, results in the loss of the sense of smell.
Speech and language are mainly attributed to parts of the cerebral cortex. Motor
portions of language are attributed to the frontal lobe and Broca’s area. Speech is
attributed to the Wernicke’s area, at the temporal-parietal lobe junction.
Factual memory is attributed to the hippocampus and associated regions of the
medial temporal lobe. This association was originally described after a patient
known as HM had both his hippocampus (left and right) surgically removed to
treat severe epilepsy, and after surgery, HM had the inability to form new
memories.
There are four lobes located in the cerebral cortex which are Frontal, Parietal,
Temporal, and Occipital.
The surface of the cerebrum the cerebral cortex is composed of six thin layers
neurons, which sit on top of a large collection of white matter pathways. The
cortex is heavily convoluted, so that if you were to spread it out, it would actually
take up about 2 ½ square feet. It includes about 10 billion neurons, with about 50
trillion synapses.
The two hemispheres of the cerebrum are intimately linked together in arch of
white matter called the corpus callosum.
The temporal lobe in the cerebrum senses of smell and sound, as well as is
Usually when someone is injured in the back of the head and fall, your sight is
blurred because if you hit the occipital lobe, it can cause blindness if you fall hard
enough.
In the cerebral cortex, there are association areas are places where cell bodies
integrate information. The somatosensory association area is located just dorsal to
the primary somatosensory area. This area processes and analyzes sensory
information from the skin and muscles.
The prefrontal area, an association area in the areas anuses this information to
reason and plan our actions. Integration in this area accounts for our most
cherished human abilities to think critically and to formulate appropriate
behaviors.
Much of the cerebrum is composed of white matter. The bulk of the cerebrum is
composed of tracts; there are subcortical nuclei deep within the white matter. The
basal nuclei serve as relay stamotor area. The basal nuclei produce that helps
control various skeletal muscle activities.
Temporal Lobe
Location
o The temporal lobes are located on both sides of the brain beneath the
frontal and parietal lobes. They are just above one’s ears.
Function
o Emotional Responses
The amygdala controls ones mood. If it is damaged, one will have
unpredictable moods and behaviors
Expression of fear
They are stimulated during spiritual or religious experiences
o Hearing
It responds to different sound frequencies and also helps in
determining the location of a particular sound.
o Memory
Hippocampus – long term memory – stores information
These memories can be anything like facts, events, people and
places
Retrieves information stored in the brain
o Speech
Left temporal lobe
Wernicke's area – controls the comprehension of words and verbal
memory
o Reading
allows you to remember what you read and stores the information
for you to recollect later
Temporal Lobe Epilepsy
o Reoccurring seizures that affect temporal lobe functions
o Many people with these seizures do not remember that they had one
o Causes
Head injury or an infection that affects the brain, such as
meningitis.
Genetics
Blood vessel malformations
o Simple Partial Seizures – consciousness is not affected
False sensations (smells, noises)
Déjà vu
Fear or anxiety usually is associated with seizures arising from the
amygdala.
Last less than 60 seconds
o Complex Partial Seizures – consciousness is affected
Unusual speech or behavior
Unable to respond to others
Last less than 2 minutes
o Medications and surgery can be used to treat this disease
Occipital Lobe
Smallest part of the brain; located at the back of the skull
o Not as vulnerable to damage as the other lobes
Processes visual information
o The retina transports visual information to this lobe through the optic
nerve
Recognition of shapes and colors
Occipital lobe epilepsy
o Unusual seizures, hallucinations, uncontrollable eye movements, fast
eye-blinking, eye pain
o Caused by genetics, tumors, vascular malfunctions, trauma, or brain
injuries
o Can be treated with medication or surgeries
Parietal Lobe
The Parietal lobes are located behind the frontal lobes and above the temporal lobes.
The lobes can be divided into two functional regions. The first one involves sensation
and perception. The other one is dealing with integrating sensory input.
The parietal lobes are used to:
-Process information
-Pain and touch sensation
-Speech
-Visual perception
-The left parietal-temporal lesions effect verbal memory and the ability to recall string of
digits.
-The right parietal-temporal lobe is concerned with non-verbal memory, and it produces
significant changes in personality.
Frontal Lobe
Frontal lobes are located at the front of the cranium. They are used for parts of
speech, movement, reasoning, and planning.
- The frontal lobes control movement by a narrow strip that goes from near the top of
the head right down along where your ear is. This strip is called the “motor strip”. If
you injure that area of the brain, you will have problems controlling half of your
body.
- Deep in the middle of the brain are sections that control emotions. They’re very
essential emotions that deal with hunger, aggression. These areas also send messages
to other parts of the brain to do something. The frontal lobe has nothing to do with
the STOP function.
- The frontal lobes play a role in speech and language. It occurs where the Broca area
is isolated, which contains motor neutrons involved in the control of speech.
- The most anterior part of the frontal lobe is involved in complex cognitive processes
like reasoning and judgment. These processes may be called biological intelligence.
Executive function regulates and directs cognitive processes, decision-making
problem solving, learning, reasoning and strategic thinking.
Neuron in Impulse Transmission
The dendrites or senders receive a short and rapid change in electrical charge or
polarity, and the neuron is triggered. Sodium ions rush through the plasma
membrane into the cell, potassium ions leave, and an electrical impulse is formed
which is conducted the cyton, which receives the impulse and transmits it to the
terminal filaments of the axon. Afterwards, a chemical transmitter acetylcholine is
released into the synapse, which is a space between the axon and of the activated
nerve and the dendrite receptors of another neuron. This chemical transmitter then
activates the next nerve and the process goes on at the speed of a bullet.
Automatically after the neuron being activated, the chemical transmitter in the
synapse is neutralized an enzyme called acetylcholinesterase and the neuron
returns to its original state by pumping out the sodium ions and pumping in the
potassium ions.
Head injuries, diseases, and drugs
Types of head injuries
-A concussion is an injury to the brain. A person,
who has a concussion usually, passes out for a
short amount of time. The person may feel dazed
and may lose vision or balance for a while after the
injury. It is normal when the person forgets the
events that happened before the accident
-A brain contusion is a bruise of the brain. This
means there is some bleeding in the brain, causing swelling.
-A skull fracture is when the skull cracks. Sometimes the edges of broken skull bones
cut into the brain and cause bleeding or other injury.
-A hematoma is bleeding in the brain that clots and then forms a bump. They may not
be apparent for a day or even as long as several weeks. Watch out for headaches,
balance problems or throwing up.
Brain Abscesses
Brain abscesses are a collection of immune cells, pus, and other material in the brain.
-These usually occur when bacteria or fungi infects part of the brain
-Swelling and inflammation usually develop in response to the infection.
-Next, a membrane forms around the infected area and creates a mass.
-This mass can cause even more damage to the brain because it causes the brain to swell.
The skull can’t expand and the mass may put pressure on soft brain tissue.
-The infected material may cause blockage of the blood vessels in the brain.
-You are at higher risk for this infection if: you have a weakened immune system, have a
chronic disease such as cancer, or take drugs that suppress the immune system.
-What are the symptoms of brain abscesses? Symptoms of this infection are: aching
neck, shoulders, or back, change in mental status, confusion, fever and chills, headache,
irritability, vision changes, vomiting, loss of muscle function. There are many more
symptoms. You may begin to experience these symptoms within 2-3 weeks depending
on your infection.
-Brain abscesses are very life threatening. Once you encounter any of these symptoms
you should go to the hospital right away.
-How do you treat this? When you do to the hospital, they will give you antibiotics.
These antibiotics will fight off the bacteria that caused the infection. Surgery may be
needed depending on the severity of the infection.
Diseases
-Epilepsy ("to seize") is a common neurological disorder characterized by recurrent
seizures. -These seizures are signs of abnormal or excessive neuronal activity in the
brain.
Epilepsy is usually controlled, but cannot be cured with medication.
Surgery may be considered in difficult cases.
-The Corpus Callosum allows the brain to function as a unit. In “normal” functioning
brain stimuli enters one hemisphere and is transferred by the corpus callosum to the
other hemisphere. In some forms of epilepsy the seizure will start in one hemisphere,
which then triggers a massive discharge of neurons through the corpus callosum and
into the second hem. To prevent such massive seizures neurosurgeons can surgically cut
the corpus callosum, which will reduce the severity of the seizures because one side of
the brain can stimulate the other. This surgical procedure is called Commissurotomy.
-Huntington's disease (HD) results from genetically programmed degeneration of
neurons, in certain areas of the brain.
-This degeneration causes uncontrolled movements, loss of intellectual faculties, and
emotional disturbance.
-HD is a familial disease, passed from parent to child through a mutation in the normal
gene.
-Some early symptoms of HD are mood swings, depression, irritability or trouble
driving, learning new things, and remembering.
-Physicians prescribe a number of medications to help control emotional and movement
problems associated with HD
-Tetrabenazine making it the first drug approved for use in the United States to treat the
disease. Most drugs used to treat the symptoms of HD have side effects such as fatigue,
restlessness, or hyperexcitability.
Scientific investigations using electronic and other technologies enable scientists to see
what the defective gene does to various structures in the brain and how it affects the
body's chemistry and metabolism. Laboratory animals are being bred in the hope of
duplicating the clinical features of HD so that researchers can learn more about the
symptoms and progression of HD. Investigators are implanting fetal tissue in rodents
and nonhuman primates with the hope of understanding, restoring, or replacing
functions typically lost by neuronal degeneration in individuals with HD.
-Alzheimer’s disease is an irreversible, progressive brain disease that slowly destroys
memory and thinking skills.
-Alzheimer’s disease is the most common cause of dementia among older people.
Dementia is the loss of functioning, thinking, remembering, and reasoning.
-Abnormal clumps (now called amyloid plaques) and tangled bundles of fibers (now
called neurofibrillary tangles). Plaques and tangles in the brain are two of the main
features of Alzheimer’s disease. The third is the loss of connections between nerve cells
(neurons) in the brain.
-Tangles begin to develop deep in the brain, in an area called the entorhinal cortex, and
plaques form in other areas. As more and more plaques and tangles form in particular
brain areas, healthy neurons begin to work less efficiently. Then, they lose their ability
to function and communicate with each other, and eventually they die. This damaging
process spreads to a nearby structure, called the hippocampus, which is essential in
forming memories. By the final stage of Alzheimer’s, damage is widespread and brain
tissue has shrunk significantly.
-Memory problems are one of the first signs of Alzheimer’s disease. Some people with
memory problems have a condition called amnesic mild cognitive impairment (MCI).
People with this condition have more memory problems than normal for people their
age, but their symptoms are not as severe as those with Alzheimer’s. More people with
MCI, compared with those without MCI, go on to develop Alzheimer’s.
Drugs
-Marijuana
The parts of the brain that control emotions, memory, and judgment are affected by
marijuana. Smoking it cannot only weaken short-term memory, but can block
information from making it into long term memory. It has also been shown to weaken
problem solving ability. People who use get the munchies because the drug affects the
hunger stimuli.
-Inhalants
The effect on the brain is almost immediate. The fatty tissues protecting the nerve cells in
the brain get destroy by the inhalant vapors. This slows down neural transmission. Effects
of this drug include: diminished ability to learn, remember, and solve problems.
Sources
Websites
http://familydoctor.org/online/famdocen/home/common/brain/head/458.html
http://www.brainsource.com/brain_on_drugs.htm
http://www.ninds.nih.gov/disorders/huntington/huntington.htm
http://www.emedicinehealth.com/brain_cancer/article_em.htm
http://www.nia.nih.gov/Alzheimers/Publications/adfact.htm
http://webspace.ship.edu/cgboer/genpsycerebrum.html
http://en.wikipedia.org/wiki/Cerebrum
http://serendip.brynmawr.edu/bb/kinser/Structure1.html
http://webspace.ship.edu/cgboer/limbicsystem.html
http://health.howstuffworks.com/brain8.htm
http://www.nlm.nih.gov/medineplus/engy/article/000783.htm
http://en.wikipedia.org/wiki/Parietal_lobe
www.endthepain.org
http://www.neuroskills.com/tbi/bcerebel.shtml
http://www.mult-sclerosis.org/cerebellum.html
http://www.cdli.ca/~dpower/resp/control.htm
http://www.wisegeek.com/what-is-the-medulla-oblongata.htm
http://www.medical-look.com/human_anatomy/organs/Medulla_oblongata.html
http://en.wikipedia.org/wiki/Medulla_oblongata
http://biology.about.com/library/organs/brain/bltemporallobe.htm
http://www.buzzle.com/articles/temporal-lobe-function.html
http://en.wikipedia.org/wiki/Temporal_lobe_epilepsy
http://www.epilepsy.com/epilepsy/epilepsy_temporallobe
http://en.wikipedia.org/wiki/Cerebrum
http://webspace.ship.edu/cgboer/genpsycerebrum.html
http://webspace.ship.edu/cgboer/limbicsystem.html
http://serendip.brynmawr.edu/bb/kinser/Structure1.html
Books
1. Human Biology book written by Sylvia S. Mader 6th edition
2. Human Biology Sixth Edition
3. Atlas of Anatomy
