Support and Protection of the Brain By Ritta Baena.

Support and Protection of the Brain

By Ritta Baena

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The Human Brain

• The Brain is the main organ of the Central Nervous System.

• It is an incredible collection of ventricles, lobes, and systems, all working together to enable you to function.

• A typical human brain, has a volume of 1200cc and weighs around 3 pounds.


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Structure of The Brain Cerebrum

– Large, main, superior component of the brain. – Conscious part of the brain– Separated into two hemispheres. Each hemisphere has five lobes.

Lobes1. movement, orientation, recognition, and perception of stimuli.

2. personality, reasoning, planning, speech, voluntary motor function of skeletal muscles, emotions, problem solving

3. visual processing.

4. perception and recognition of auditory stimuli, memory, and speech, smell

5. regulation and coordination of movement, posture, and balance.

Brain StemResponsible for basic vital life functions such as breathing, heartbeat, and blood pressure.

Mid-BrainActs like a complex switchboard, allowing the brain to communicate with the rest of the nervous system.

PonsRelays messages from the cerebrum to the cerebellum and spinal cord.

Medulla OblongataLocated above spinal cord. Regulates vital functions, such as heartbeat and breathing. Responsible for Coughing, Sneezing, Vomiting, Salivating, Swallowing, Gagging

Spinal CordResponsible for carrying information from brain to end organs to support basic functions

Frontal Lobe:

Parietal Lobe:

Occipital Lobe:

Temporal Lobe:

Cerebellum:


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Brain Development

• As a human embryo develops, the brain begins to develop from the rostral (anterior) part of the neural tube.

• At this point it undergoes a disproportionate rate of growth in different regions.

• By the 5th week of embryonic development, a total of 5 regions appear; the telencephalon, diencephalon, mesencephalon, metencephalon, and mylencephalon.

• As the brain continues to develop, the telencephalon will fold and eventually form the cerebrum containing sulci and gyri.

– The sulci and gyri which develop in the late fetal stage are necessary to be able to fit the large amount of brain tissue into the confines of the cranial cavity.

• As the telencephalon rapidly grows, it wraps around the diencephalon that later forms the thalamus, hypothalamus and epithalamus.

• The mesencephalon is the only region that doesn't form a new secondary vesicle.

• The metencephalon eventually forms the pons and cerebellum.

• The meylencephalon eventually forms the medulla oblongata.

Spinal Cord

Myelencephalon

Metencephalon Rhombencephalon

(hindbrain)

Mesencephalon

(midbrain)

Prosencephalon

(forebrain)

Diencephalon

Telencephalon


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• The brain is very soft, having a consistency similar to tofu and needs to be protected.

• The brain is protected by the thick bones

of the skull (Cranium), supported by Cerebrospinal fluid(CSF),

and isolated by the

blood-brain barrier (BBB).

What supports and Protects the brain?


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1. Cranial bones - Provides rigid support and protection for the brain

2. Connective Tissue called meninges– Separates the soft tissue of the brain

from the bones of the cranium– Encloses and protects blood vessels

that supply the brain– Contains and circulates cerebrospinal

fluid. – Consists of the Dura Mater,

Arachnoid Mater and Pia Mater.



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3. Cerebrospinal Fluid (CSF)

Cerebrospinal fluid allows Environmental Stability, Protection, and Buoyancy

• Clear colorless liquid that circulates in ventricles and subarachnoid space formed by ependymal cells and blood cappillaries • CSF is present in each of the 4 ventricles.

CSF flows from the lateral ventricles of the brain, through the intraventricular foramen, into the third ventricle.

From this point it travels down the mesencephalic aqueduct to the fourth ventricle and either into the central canal of the spinal column or out through the median aperture into the subarachnoid space.

Next it moves to the arachnoid villi and empty into the dural venous sinus and return to the blood.



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4. Blood-brain Barrier

• The blood-brain barrier (BBB) is a metabolic or cellular structure in the central nervous system (CNS) that restricts the passage of various chemical substances and microscopic objects (e.g. bacteria) between the bloodstream and the neural tissue itself, while still allowing the passage of substances essential to metabolic function (e.g. oxygen).

• Prevents the entry of harmful materials from the bloodstream.

• Astrocytes envelope the brain's capillaries and reduce permeability of the capillaries.

• Usually only lipid-soluble compounds can be diffuse across the capillary walls into the CSF and reach the brain neurons.

• The blood-brain barrier is absent or greatly reduced in three distinct locations of the brain. Namely in the choroid plexi, hypothalamus, pineal gland.



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How brain synapses work

Each individual cell contains 1,000 to 10,000 synapses (connections) as in figures below

We can gain a better understanding of how they fail, causing brain damage and dementia by studying the functions of these synapses .


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The blood-brain barrier (BBB) • is a metabolic or cellular structure in the central

nervous system (CNS) • It restricts the passage of various chemical

substances and microscopic objects (e.g. bacteria) between the bloodstream and the neural tissue itself, while still allowing the passage of substances essential to metabolic function (e.g. oxygen & glucose).

• The blood-brain barrier acts very effectively to protect the brain from many common bacterial infections. Thus, infections of the brain are very rare. However, since antibodies are too large to cross the blood-brain barrier, infections of the brain which do occur are often very serious and difficult to treat.

• Viruses easily bypass the blood-brain barrier, however, attaching themselves to circulating immune cells.

Pathophysiology of the Blood Brain Barrier


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• Meningitis inflammation of the membranes which surround the brain and spinal cord caused by infections (Streptococcus pneumoniae and Haemophilus influenzae). When the meninges are inflamed, the blood-brain barrier may be disrupted thus penetration of various substances (including antibiotics) into the brain.

• Epilepsy is a common neurological disease characterized by frequent and often untreatable seizures. Several clinical and experimental data have implicated failure of blood-brain barrier function in triggering chronic or acute seizures These findings have shown that acute seizures are a predictable consequence of disruption of the BBB by either artificial or inflammatory mechanisms. In addition, expression of drug

resistance molecules and transporters at the BBB are a significant mechanism of resistance to commonly used anti-epileptic drugs.

Diseases Compromises BBB


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• Multiple sclerosis (MS) is considered an auto-immune disorder in which the immune system attacks the myelin protecting the nerves in the central nervous system.

– Normally, a person's nervous system would be inaccessible for the white blood cells due to the

blood-brain barrier. – Magnetic Resonance Imaging shows that, when a person is undergoing an MS "attack," the blood-brain barrier has broken down in a section of the brain or spinal cord, allowing white blood cells

called T lymphocytes to cross over and destroy the myelin. – It has been suggested that, rather than being a disease of the immune system, MS is a

disease of the blood-brain barrier. However, current scientific evidence is inconclusive. – It is believed that oxidative stress plays an important role into the breakdown of the barrier;

anti-oxidants such as lipoic acid may be able to stabilize a weakening blood-brain barrier.

• Neuromyelitis optica (Devic's disease) is similar to and often confused with multiple sclerosis. Among other differences from MS, the target of the autoimmune response has been identified.Patients with neuromyelitis optica have high levels of antibodies against a protein called aquaporin 4 (a component of the astrocytic foot processes in the blood-brain barrier).


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• Late-stage neurological trypanosomiasis (Sleeping sickness) is a condition in which trypanosoma protozoa are found in brain tissue. It is not yet known how the parasites infect the brain from the blood, but it is suspected that they cross through the choroid plexus (Any of the highly vascular, folded processes that project into the third, fourth, and lateral ventricles of the brain), a circumventricular organ.

• Progressive multifocal leukoencephalopathy (PML) is a demyelinating disease of the central nervous system caused by reactivation of a latent papovavirus (the JC polyomavirus) infection, that can cross the BBB. It affects immune-compromised patients and is usually seen with patients having AIDS.

• De Vivo disease (also known as GLUT1 deficiency syndrome) is a rare condition caused by inadequate transport of glucose across the barrier, resulting in mental retardation and other neurological problems. Genetic defects in glucose transporter type 1 (GLUT1) appears to be the main cause of De Vivo disease.


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• Alzheimer's Disease (AD) New evidence indicates that disruption of the blood-brain barrier in AD patients allows blood plasma containing amyloid beta (Aβ) to enter the brain where the Aβ adheres preferentially to the surface of astrocytes. These findings have led to the hypotheses that

– breakdown of the blood-brain barrier allows access of neuron-binding autoantibodies and soluble exogenous Aβ42 to brain neurons

– binding of these autoantibodies to neurons triggers and/or facilitates the internalization and accumulation of cell surface-bound Aβ42 in vulnerable neurons through their natural tendency to clear surface-bound autoantibodies via endocytosis.

– Eventually the astrocyte is overwhelmed, dies, ruptures, and disintegrates, leaving behind the insoluble Aβ42 plaque. Thus, in some patients, Alzheimer’s disease may be caused (or more likely, aggravated) by a breakdown in the blood brain barrier.

NOTE: The herpes virus produces the amyloid beta (Aβ) and has been found to be the pathogen responsible for being a major cause of Alzheimer’s disease.

• Encephalitis: an acute inflammatory disease of the brain, most often due to viral infections. Symptoms include drowsiness, fever, headache, neck pain, coma, and paralysis. Death may occur.

• HIV Encephalitis It is believed that latent HIV can cross the blood-brain barrier inside circulating monocytes in the bloodstream ("Trojan horse theory") within the first 14 days of infection.

– Once inside, these monocytes become activated and are transformed into macrophages. – Activated macrophages release virions into the brain tissue proximate to brain

microvessels. These viral particles likely attract the attention of sentinel brain microglia and perivascular macrophages initiating an inflammatory cascade that may cause a series of intracellular signaling in brain microvascular endothelial cells and damage the functional and structural integrity of the BBB. This inflammation is HIV encephalitis (HIVE).

– Instances of HIVE probably occur throughout the course of AIDS and are a precursor for HIV-associated dementia (HAD).


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Infant Brain Disorders

Premature birth disordersIn the USA, around 12% of babies are born prematurely• Disorders may evolve from even the mildest brain injury sustained at birth• Premature birth is associated with a very high rate of neuro developmental problems • Caused by oxygen deprivation or infection

Cerebral palsy• Group of neuromuscular disorders that usually result from damage to an infant's brain before, during, or immediately after birth. • Three forms of cerebral palsy involving impairment of skeletal motor activity to some degree are:

• athitoid - slows involuntary, writhing hand movements• ataxic - lack of muscular coordination• spastic - increased muscular tone. Mental retardation and speech difficulties may accompany this disorder.


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Brain Disorders & Injuries• Headache: Sometimes due to tumors, hemorrhage, meningitis, or

inflamed nerve roots. More common causes are emotional stress, increased blood pressure, and food allergies, all of which cause blood vessel diameter changes. Migraine headaches are severe, recurring headaches that usually affect one side of the head.

• Huntington disease: An autosomal dominant disease that affects the cerebral nuclei. It causes rapid, jerky, involuntary movements that usually start unilaterally in the face, but over months and years progress to the arms and legs. Progressive intellectual deterioration also occurs, including personality changes, memory loss, and irritability. The disease is fatal within 10-20 years of it starting.

• Parkinson disease: A slow-progressing neurological condition that affects muscle movement and balance. Parkinson exhibit stiff posture, an emotionless face, slow voluntary movements, a resting tumor, and a shuffling gait. Causes include medication reaction, effects of certain illicit drugs, and genetics, but most cases occur with no obvious cause.

• Rostrocaudal Deterioration: When the cerebrum pushes • down through the tentorial incisure because of head trauma, • intracranial bleeding, tumors, inflammation, or cerebral

edema


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Brain Disorders & Injuries

• Cerebrovascualr Accident: Thrombus (blood clot) or rupture of blood vessel in the brain which prevents the brain from getting oxygen.

• Concussion: characterized by a temporary, abrupt loss of consciousness after a blow to the head or the sudden stop of a moving head. There is no obvious physical difference after a concussion, but headaches, drowsiness, lack of concentration, confusion, and amnesia may be a result. Multiple concussions have a cumulative effect.

• Contusion: a visible bruising due to trauma that causes blood to leak from the small vessels.

– May result from a torn pia mater, which permits blood to enter the subarachniod space.

– Usually individual loses consciousness. Respiration abnormalities and blood pressure decrease may also occur.

• Physical damage: The most common forms are closed head injuries, caused by

– Blow to the head; – Stroke, caused by interruption of the brain's blood supply– Poisoning, caused by a wide variety of chemicals that can act as neurotoxins.

• Brain Tumors: defined as any intracranial tumor created by abnormal and uncontrolled cell division, normally in the brain itself


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Primary Brain Tumors

Risk factors associated with an increased chance of developing a primary brain tumor:

• Being male - In general, brain tumors are more common in males than females. However, meningiomas are more common in females.

• Race - Brain tumors occur more often among white people than among people of other races.

• Age - Most brain tumors are detected in people who are 70 years old or older. However, brain tumors are the second most common cancer in children. (Leukemia is the most common childhood cancer.) Brain tumors are more common in children younger than 8 years old than in older children.

• Family history - People with family members who have gliomas may be more likely to develop this disease.

• Exposure -to radiation or certain chemicals:

– Radiation - Workers in the nuclear industry have an increased risk of developing a brain tumor.

– Formaldehyde - Pathologists and embalmers who work with formaldehyde have an increased risk of developing brain cancer. Scientists have not found an increased risk of brain cancer among other types of workers exposed to formaldehyde.

– Vinyl chloride - Workers who make plastics may be exposed to vinyl chloride. This chemical may increase the risk of brain tumors.

– Acrylonitrile - People who make textiles and plastics may be exposed to acrylonitrile. This exposure may increase the risk of brain cancer.

• Cell Phones - Scientists are investigating whether cell phones may cause brain tumors. Studies thus far have not found an increased risk of brain tumors among people who use cell phones.


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Brain Cancers

Brain Cancers are abnormal growths of cells in the brain. Not all brain tumors are cancers. Cancer is a term reserved for malignant tumors.

• Malignant tumors grow and spread aggressively, overpowering healthy cells by taking their space, blood, and nutrients. (Like all cells of the body, tumor cells need blood and nutrients to survive.)

• Benign Tumors do not spread aggressively are less serious than a malignant tumor but can still cause many problems in the brain.

Primary Brain Cancers– Brain tumors that result from transformation and abnormal growth of brain cells are called primary brain

tumors because they originate in the brain. – The most common primary brain tumors are gliomas, meningiomas, pituitary adenomas, vestibular

schwannomas, and primitive neuroectodermal tumors (medulloblastomas). The term glioma includes astrocytomas, oligodendrogliomas, ependymomas, and choroid plexus papillomas.

– Most of these are named after the part of the brain or the type of brain cell from which they arise.

Metastatic Brain Cancer– Metastatic brain tumors are made of cancerous cells from a tumor that originate elsewhere in the

body. – The cells spread to the brain from another tumor in a process called metastasis. About 25% of tumors

elsewhere in the body metastasize to the brain. (In the United States, brain tumors affect about 1 of every 5000 people)


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Brain Injuries

• Traumatic brain injury (TBI) is a leading cause of death in the USA for persons under age 45.

– Causes whiplash - motor vehicle accident, falls, and sports injuriescan stretch, twist, and damage the delicate axonal fibers

– TBI occurs every 15 seconds. – Approximately 5 million Americans currently suffer some form of TBI

disability. – TBI, has become the signature injury of the war in Iraq

• High cholesterol often means a gradual build-up of plaque in blood vessel walls. This can then restrict blood flow to the brain — which limits oxygen and nutrients, not a good combination for keeping the brain healthy.

• High blood pressure can affect the brain by causing blocked or broken blood vessels, which can kill brain cells by cutting off oxygen as well. High blood pressure can also weaken the connection between the brain and the body ("blood brain barrier"), which may allow substances to enter the brain that can cause damage.


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Brain Injuries -Hemorrhages

• Intracerebral hemorrhageCoronal section through the skull reveals a intracerebral hemorrhage. The central large dark area represents the hemorrhage. Note the midline shift.

• Epidural hematomaCoronal section through the skull and brain reveals a epidural hematoma. The dark area in the lower left area is the hematoma. Note the broken blood vessel and the shift of midline structures.

• Subdural hematomaCoronal section through the skull and brainreveals a subdural hematoma. The dark area inthe upper left area is the hematoma.


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Protecting Your Brain – New Treatments

Progesterone

• While progesterone is most often thought of as a pregnancy-related hormone, it really is a hormone made by the brain, for the brain.

• Progesterone is vital for brain cells -- which may explain why progesterone levels are so high during pregnancy. Researchers suggest it could protect the fetus during the critical time of brain cell maturation.

• In a small, preliminary study of 100 patients published recently in the Annals of Emergency Medicine, doctors gave brain injury patients high intravenous doses of the pregnancy hormone progesterone within 12 hours of injury.

• Patients who received the hormone cut their risk of dying by 57 percent.

• Repairing the brain and spinal cord after injury is very similar to pregnancy. You have to grow new neurons.

• Such a feat was once thought to be impossible, as most scientists believed the brain to be incapable of repairing itself after injury. Until now, all doctors could do for TBI patients was to prevent swelling and keep patients alive until the brain recovers itself.


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Protecting Your Brain – New Treatments

Nanotechnology - Nanoparticles• 95% of all therapeutics that in principle are suitable for the treatment of

CNS diseases do not pass the blood brain barrier (BBB) in therapeutically relevant doses. In order to overcome this limitation nanoparticle based technology which allows or improve the transport of pharmaceutical active compounds loaded into nanoparticles (NP) across the BBB. In addition, pharmaco-kinetic and-dynamic drug parameters can be improved.

• Drug delivery technologies for crossing the blood brain barrier central nervous system (CNS) for the treatment of brain tumors and other diseases of the central nervous system (CNS). .

• Nanotechnology may also help in the transfer of drugs across the BBB. Recently, researchers have been trying to build liposomes loaded with nanoparticles to gain access through the BBB.

• Doxorubicin loaded into nanoparticles, is in preclinical stage to treat devastating primary and secondary brain tumors. Doxorubicin-nanoparticles already tested successfully in mice and rats are expected to enter phase Ia/IIb trials with glioma patients in second half of 2009.

• The technology could initiate a therapeutic breakthrough for the treatment of brain cancer as well as other brain related diseases with high unmet medical needs, e.g. pain, migraine, depression and Alzheimer’s. delivery technology to develop preferentially drugs


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Protecting your Brain

As we age, the brain does in fact start to change. Recently, numerous studies have focused on this subject to see what we can all do to preserve our brains and reduce the risk of difficulties with memory, language and emotion, dementias and Alzheimer's disease later in life.

• Healthy diets that includes a lot of fruits, vegetables, whole grains, nuts, seeds, beans, low-fat dairy products, and lean protein foods provides numerous nutrients that can benefit the brain and other body tissues.

• Vitamin Supplements – Vitamin D in high dosages (at least 1000 IU) are related to better brain function and users have performed better

on tests related to abstract thinking, planning, organizing, paying attention to details, and forming concepts. They also had less damage to the small blood vessels in the brain. Vitamin D may also reduce the risk of cardiovascular disease. Since vitamin D is hard to find in the diet, consider a daily supplement of at least 1000 IU.

– Vitamin B12 found in meat, fish and milk, may protect against brain volume loss in older people, according to a study published in the September 9, 2008, issue of Neurology®, the medical journal of the American Academy of Neurology.

• Omega-3 fatty acid docosahexaenoic acid (DHA) one of the major building blocks of the brain is critical for optimal brain health and function at all ages of life. Researchers are now finding that DHA provides brain-boosting benefits in infants and aging adults.

• Coffee Some studies suggest less dementia in coffee drinkers, which could be attributed to a number of factors. One hypothesis is that caffeine is anti-inflammatory and may reduce inflammation in the brain.


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Protecting your Brain• Continually challenge your brain Your brain is like your muscles "use it or lose it." Continually

challenging your brain mentally can go a long way toward maintaining brain function. Keeping mentally active means

– better brain performance – a delay in having more serious Alzheimer's disease, memory loss or dementias.

• A balanced diet and regular exercise can protect the brain and ward off mental disorders. Athletes and people who exercise not only have better body but better brains too. Exercisers

– learn faster– remember more– think clearer – bounce back more easily from brain injuries such as a stroke. – Are less prone to depression and age-related cognitive decline.

• Aerobic exercise is a threat to the body's energy reserves. Heeding this danger, the body acts to protect one of its most precious, and energy-demanding, organs: the brain.

– Exercise protects the brain and improves brain function but overdoing it, can be dangerous. – Unlike cells in less critical organs, neurons are extremely vulnerable to disruptions in energy supply (oxygen

and Sugar). If deprived of energy for more than a few minutes, the neuron dies. – The physiology of the body is designed to protect the brain and in case of serious threat, the body will protect

the brain at the expense of muscles, by converting the protein to glucose.

• Proper Sleep is absolutely necessary to maintain brain health and function. Sleep deprivation causes sluggishness, tiredness and poor performance in general. Sleep Apnea has recently received widespread attention

• Avoid Stress – Like sleep, stress causes sluggishness, tiredness and poor performance in general.


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Damaged brains are NOT easy to fix. Here are some suggestions for protecting your most valuable asset.

1. Wear your seat belt! In a car, truck or airplane, to help protect your head and brain from injury.

2. Wear your helmet while biking, skating or skateboarding, your helmet will protect your head if you fall. Make sure that your helmet meets or exceeds the American National Standards Institute (ANSI) and Snell Memorial Foundation standards for safety. Head injury is the most common cause of death in bicycle crashes accounting for 62% of all bicycle-related deaths.

3. Avoid illegal drugs! Drugs alter brain function. Although damage done by some drugs can sometimes be reversed, some drugs may change brain function permanently. Avoid drug and alcohol especially during pregnancy.

4. Avoid Risky Sports! Know the risks involved with sports. 5. Look before you leap into a swimming pool 6. Look both ways before crossing the road7. Stay away from guns. Use Safety locks and secure cabinets during storage.8. Make sure there is a "good" surface around playground equipment! 9. Eat right! Proper nourishment increases health and longevity of the brain.10. Dispose of chemicals properly! Environmental pollutants can cause long

term brain problems

Protecting your Brain Prevention is Better than Cure


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Current Event: Epidural Hematoma

March 19, 2009, actress Natasha Richardson died following a head injury classified as an "epidural hematoma". She had fallen while taking skiing lessons. Paramedics were brought to the scene but sent away as "not necessary" and never examined her. Unfortunately, she died within two days of this accident.


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Interesting facts about the Brain

1. The brain operates on the same amount of power as 10-watt light bulb.

2. Your brain uses 20% of the oxygen that enters your bloodstream. The brain only makes up about 2% of our body mass, yet consumes more oxygen than any other organ in the body, making it extremely susceptible to damage related to oxygen deprivation. So breathe deep to keep your brain happy and swimming in oxygenated cells.

3. Scientists say the higher your I.Q. the more you dream. While this may be true, don’t take it as a sign you’re mentally lacking if you can’t recall your dreams. Most of us don’t remember many of our dreams. The average length of most dreams is 2-3 seconds–barely long enough to register

4. The human brain can hold 5 times as much information as the Encyclopedia Britannica. Or any other encyclopedia for that matter. Scientists have yet to settle on a definitive amount, but the storage capacity of the brain in electronic terms is thought to be between 3 or even 1,000 terabytes. The National Archives of Britain, containing over 900 years of history, only takes up 70 terabytes, making your brain’s memory power pretty darn impressive.

5. Nerve impulses to and from the brain travel as fast as 170 miles per hour. Ever wonder how you can react so fast to things around you or why that stubbed toe hurts right away? It’s due to the super-speedy movement of nerve impulses from your brain to the rest of your body and vice versa, bringing reactions at the speed of a high powered sports car.

6. The brain itself cannot feel pain. While the brain might be the pain center when you cut your finger or burn yourself, the brain itself does not have pain receptors and cannot feel pain. That doesn’t mean your head can’t hurt. The brain is surrounded by loads of tissues, nerves and blood vessels that are receptive to pain and can give you a headache.

Support and Protection of the Brain By Ritta Baena.

Documents

level brain development

brain tissue

level structure

brain cerebrum large

brain stem responsible

typical human brain

bloodbrain barri

midbrain acts