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Chapter

PS263 - Ch 10 Textbook.docx

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Department
Psychology
Course Code
PS263
Professor
Todd Ferretti

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Brain Tumors  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 the cheeks 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. Neuropsychological Diseases Epilepsy: Applies to those who have spontaneously recurring epileptic seizures – 1% of the population – convulsions: (motor seizures) often involve
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