A tumor (neoplasm – new growth) a mass of cells that grows independently
of the rest of the body – it is a cancer.
20% of tumors found in the brain are meningioma’s – tumors that grow
between the meninges (3 membranes covering the CNS)
o Encapsulated: Tumors that grow within their own membrane; they
influence function of the brain by pressure they exert on surrounding.
o Acoustic Neurons: neuromas are tumors that grow on nerves or tracts)
o Benign: Tumors that are surgically removable with little risk of
further growth in the body.
Infiltrating Tumors that grow diffusely through surrounding tissue.
o Malignant: Difficult to remove or destroy them completely – any
cancerous tissue that remains after surgery continues to grow.
o 10% of brain tumors do not grow in the brain – grow from infiltrating
cells carried to the brain in the bloodstream from another part of body.
o Metastatic: refers to transmission of disease from one organ to
another – many originate as cancers in the lungs
Cerebrovascular Disorders: Strokes
Strokes: are sudden-onset cerebrovascular disorders that cause brain
damage – leading cause of death in the US, most common disability.
Symptoms of stroke depend on area of the brain that is affected; amnesia,
aphasia (language difficulties), paralysis, and coma.
The area of dear/dying tissue produced by a stroke is called infarct –
surrounding it is the penumbra: this tissue may recover or die, depending
on a variety of factors – goal is to save it
Cerebral Hemorrhage: (Bleeding in the brain) occurs when a cerebral blood
vessel ruptures & blood seeps into the surrounding neural tissue & damages
it – bursting aneurysms are a common cause of intracerebral hemorrhage.
o Aneurysm: pathological balloonlike dilation that forms in the wall of
an artery at a point where elasticity of the artery wall is defective.
o Congenital: (aneurysm present at birth) or can result from exposure
to vascular poisons or infection avoid exercising with aneurysm.
Cerebral Ischemia: Disruption of the blood supply to an area of the brain:
1. Thrombosis: A plug called a thrombus is formed & blocks blood flow at site
of formation; blood clot, fat, oil, air bubble, tumor cells, or any combination.
2. Embolism: Plus called embolus is carried by the blood from a larger vessel
where it was formed to a smaller one and becomes lodged – throm. on a trip.
3. Arteriosclerosis: The walls of blood vessels thicken & channels narrow,
usually as a result of fat deposits – lead to complete blockage of blood vessels
Much brain damage is a consequence of excessive release of excitatory amino
acid transmitters – glutamate – most prevalent excitatory NT.
1. Blood vessel becomes blocked.
2. Neurons that are affected by the ischemia release excessive glutamate.
3. Excessive glutamate binds to NMDA receptors, triggering excessive influx of
Na and Ca ions into postsynaptic neurons. 4. Excessive influx of Na and Ca ions eventually kills postsynaptic neurons –
but first triggers the excessive release of glutamate from them – toxic cascade
Ischemia based brain damage: 1) takes a while to develop, 2) does not occur
equally in all parts of the brain, 3) mechanisms vary from structures within
the brain & astrocytes have been implicated in some areas.
Closed Head Injuries: Brain injuries produced by blows that do not penetrate the
skull. Hematoma: localized collection of clotted blood in tissue (bruise)
Contusions: that involve damage to the cerebral circulatory system – occur
when the brain slams against the side of the skull; subdural space: space
between dura matar & arachnoid membrane – distorts
Contrecoup Injuries: The blow causes the brain to strike the inside of the skull on
the other side of the head Concussion: when there is a disturbance of consciousness
following a blow to the head & no evidence of contusion or other structural damage
– damage can last up to years.
Punch-Drunk Love: the dementia & cerebral scarring observed in boxers &
other individuals who experience repeated concussions
Infections of the Brain: Invasion of the brain my microorganisms is a brain infection
and the resulting inflammation is encephalitis.
Bacterial Infections: Leads to the formation of cerebral abscesses: pockets
of pus in the brain – major cause of meningitis (inflammation of meninges)
Syphilis: Bacteria passed from infected to noninfected individuals through
contact with genital sores – result in insanity & dementia = general paresis.
Viral Infections: 1) those that have a particular affinity for neural tissue 2)
those that attack neural tissue but have no greater affinity for it than others.
Rabies – from rabid animals, affinity for nervous system; brain in 1 month.
Mumps & Herpes – attack nervous system with no affinity for it – to brain.
Neurotoxins: Damages by exposure to a variety of chemicals – enter general
circulation from gastrointestinal tract, lungs or skin; toxic psychosis: chronic
insanity produced with a neurotoxin; endogenous: produced by patients own body
Tardive Dyskinesia (TD): Involuntary smacking & sucking movements of
the lips, thrusting & rolling of the tongue, lateral jaw movements, puffing of
Genetics: Caused by abnormal recessive genes that are passed from parent to child
Down Syndrome: Occurs in 0.15% of births – during the mothers ovulation,
extra chromosome 21 is created within the egg – when fertilized there are 3
of the chromosome rather than 2 = disfigurement, intellectual impairment,
etc. – more likely with mothers age rising (1 in 2000 at 20 – 1 in 11 at 49)
Programmed Cell Death: Apoptosis: cells destroy themselves – proceeds gradually,
shrinking the cell body, as parts die, debris is packaged in vesicles = no
inflammation & damage to nearby cells is kept to a minimum.
Epilepsy: Applies to those who have spontaneously recurring epileptic seizures –
1% of the population – convulsions: (motor seizures) often involve