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PSYB64H3 (201)
Chapter 15

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Janelle Leboutillier

15 | NEUROLOGICAL DISORDERS Brain Damage Stroke - figure 15.2, p.432 – nervous system unable to rely on stored supplies of oxygen because can be interrupted by ruptures and blockages of blood vessels serving brain - stroke: type of brain damage caused by interruption of blood supply to brain  risk factors: age, hypertension, smoking, diabetes, high cholesterol, obesity and use of alcohol, cocaine, amphetamines heroin, and other drugs  increased risk: arteries are narrowed gradually - cerebral hemorrhage: condition caused by bleeding in the brain  gradually results from hypertension or structural defects in arteries serving brain  some occur due to rupture of aneurysms: balloon like bulge in wall of an artery  interferes w/ blood supply to neurons and flooding areas of brain w/ salty blood that dehydrates and kills nearby neurons - blockages of blood vessels result in ischemia: condition in which inadequate blood flow results in insufficient quantities of oxygen being delivered to tissue  account for 80% of all strokes  often results in death of neural tissue –figure 15.3, p.433: infarct: area of dead neural tissue  Transient ischemic attacks (TIAs): brief (42hr or less) episode of stroke symptoms that does not cause permanent damage - thrombosis: blockage that doesn’t move from its point of origin in a blood vessel - embolism: blood vessel blockage that originated elsewhere and traveled to its current location - damage related to ischemia not widespread, affected cells in middle layers of cortex and hippocampus=most vulnerable - excitotoxicity  high concentrations of magnesium prevented cell death cultures of rat hippocampal cells  magnesium blocks NMDA glutamate receptor  now believed cell death following strokes largely caused by excess glutamate triggered by disruptions in delivery of oxygen - in response to excess glutamate=abnormal calcium activity stimulates four “executioner” enzymes that damage cell’s energy stores, membranes, cytostructure, and DNA - some cells die immediately following stroke, can save many in ischemic penumbra: area of tissue surrounding infarct Head Injuries - traumatic brain injuries (TBI): physical damage to the brain –divided into two categories: 1) open head injuries: head injury where brain is penetrated, as in a gunshot wound 2) concussions: head injury that results from blow to the head w/out penetration of brain or blow to another part of body that results in force transmitted to the brain - concussions produce damage in several ways –figure 15.4, p.433  coup: area of brain damage at site of blow to the head (might be damaged by compression of skulls against neural tissue)  countercoup: area of brain damage that occurs on opposite side of head from original site of blow, or coup  subdural hematoma: mass of clotted blood (like a bruise) that forms between dura mater and arachnoid following head injury  white matter damage=twisting of brain w/in skull - postconcussion syndrome (PCS): set of symptoms that follow concussion for a period of days to years, including headache, cognitive deficits, and emotional changes  correlate dw/ damage in # of brain damagesincluding white and gray matter - chronic traumatic brain injury (CTBI): type of brain damage caused by repeated concussions  dementia pugilistica: severe form of CTBI often experienced by boxers - having E variant of APOE gene seemed more vulnerable Brain Tumors - tumor: independent growth of tissue that lacks purpose - usually don’t arise form mature neurons (don’t replicate); mostly come from glial cells and from cells of meninges; small originate in cells lining ventricles - malignant tumor: type of abnormal cell growth that, lacking boundaries, invades surrounding tissue and very likely to recur following surgical removal - metastasis: migration of cancerous cells from one part of the body to another - benign tumor: abnormal cell growth that develops w/in its own membrane and unlikely to recur following surgery and don’t metastasize Symptoms of Tumors - all produce general symptoms due to pressure w/in skull –including: headache, vomiting, double vision, reduced heart rate, reduced alertness, and seizures - specific symptoms due to location of tumor occurs Types of Tumors - identified according to tissue from which they arise - gliomas: tumor that develops from glial cells –account for approx. 45% of brain tumors, often arise in astrocytes, oligodendrocytes, or mixtures of two - figure 15.6, p.436 meningioma: tumor arising from tissue of meninges - WHO issued classification system for central nervous system tumors: Grade I-IV Treatment for Tumors - most common is surgical removal - if surgery risky or impossible=radiation, chemotherapy through blood stream (hard for brain tumors since some can’t cross blood brain barri
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