Chapter 15 Textbook Notes

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9 Dec 2010
PSYB64: An Introduction to Physiological Psychology
Chapter 15: Neurological Disorders
Brain Damage
- Soccer players perform worse on tests for attention, memory, and planning compared to
swimmers and track athletes
o Many have cerebral atrophy because of head injuries
- Brain protected by skull bones/meninges, cerebrospinal fluid (CSF), and blood-brain barrier
- Cells in nervous system (NS) rely on oxygen which is supplied by rich network of blood vessels
o Circulation of blood to neural tissue can be ruptured/blocked t can cause serious
damage to brain
- Stroke = type of brain damage caused by an interruption of blood supply to the brain
- Risk factors of stroke = age, hypertension, smoking, diabetes, high cholesterol, obesity, alcohol
use, cocaine, amphetamines, heroin, and other drugs
- Atherosclerosis also increases risk of stroke = when arteries are narrowed/hardened
- Cerebral hemorrhage = condition caused by bleeding in the brain
o Gradually results from hypertension (high blood pressure) or structural defects in
arteries serving brain
o Sometimes occur due to aneurysms = balloon-like bulge in artery wall
o Can occur from diseases t leukemia, exposure to toxic chemicals, etc.
o Usually fatal because of damage produced by blocking blood supply to neurons and
flooding areas of brain with salty blood that dehydrates and kills neurons
- Ischemia = condition where inadequate blood flow results in insufficient quantities of oxygen
being delivered to tissue
o Low oxygen levels
o Can result in neural tissue death in an area = infarct t causes changes in consciousness,
sensation, ability to move (depends on size/location)
- Transient ischemic attacks (TIAs) = brief (less than 24 hours) episode of stroke symptoms that
๎€š}๎€ž๎‚v[๎‚š๎€ƒ๎€๎€‚ยต๎‚๎€ž๎€ƒ๎‚‰๎€ž๎‚Œu๎€‚v๎€žv๎‚š๎€ƒ๎€š๎€‚u๎€‚P๎€ž๎€ƒt strong predictors of subsequent strokes
- Thrombosis = blockage ๎‚šZ๎€‚๎‚š๎€ƒ๎€š}๎€ž๎‚v[๎‚š๎€ƒu}ร€๎€ž from its point of origin in blood vessel
- Embolism = blood vessel blockage that travel through smaller and smaller blood vessels until
forms actually blockage
o Blockage in small blood vessels are less damaging than in large blood vessels but
multiple small strokes can cause damage
- Cells in middle layers of cortex and hippocampus are most vulnerable to ischemia
- Excitotoxicity t John Olney = ability of excess glutamate to kill neurons
o Now believe that cell death after stroke is caused by excess glutamate activity triggered
by lack of oxygen
- Excess glutamate in neuron initiates cascade of events t leads to cell death
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PSYB64: An Introduction to Physiological Psychology
o ๎€„๎€v}๎‚Œu๎€‚o๎€ƒ๎€๎€‚o๎€]ยตu๎€ƒ๎€‚๎€๎‚š]ร€]๎‚šร‡๎€ƒ]v๎€ƒ๎€๎€žoo๎€ƒ๎‚๎‚š]uยตo๎€‚๎‚š๎€ž๎‚๎€ƒรฐ๎€ƒZ๎€žร†๎€ž๎€ยต๎‚š]}v๎€ž๎‚Œ[๎€ƒ๎€žvรŒร‡u๎€ž๎‚๎€ƒ๎‚šZ๎€‚๎‚š๎€ƒ๎€š๎€‚u๎€‚P๎€ž๎€ƒ๎€๎€žoo[๎‚๎€ƒ
energy stores, membranes, cytostructure, and DNA
- To reduce risk of stroke = surgery, reduce formation of thromboses and emboli, reduce blood
- Penumbra = areas of tissue surrounding an infarct t surgery used to save neurons/glia in this
Head Injuries
- Traumatic brain injuries = physical damage to the brain
o Usually caused by traffic accidents, gunshot wounds, falls
- Divided into 2 categories:
o Open head injuries = penetration of skull
๎‚ƒ Usually because of gunshot wound or fractures of skull where bone fragments
enter brain
๎‚ƒ Most fatal when damage is caused in ventricles, both hemispheres, or multiple
lobes in brain
o Concussions/closed head injuries = occurs because of blows to the head or to the body
that caus๎€ž๎‚๎€ƒ^]u๎‚‰ยตo๎‚]ร€๎€ž_๎€ƒ(}๎‚Œ๎€๎€ž๎€ƒ๎‚š๎‚Œ๎€‚v๎‚u]๎‚š๎‚š๎€ž๎€š to brain
๎‚ƒ Can be mild = no loss of consciousness or for only a brief time
๎‚ƒ Can be severe = coma
๎‚ƒ Can cause physical, behavioural, and cognitive problems t lasts for months or
can be permanent
- Coup = damage to brain where blow to the head occurs
o Can cause damage by compression of the skull against neural tissue
- Countercoup = damage to brain on the opposite side of blow because force of blow pushes
brain against the skull opposite the coup
- Severe coup/countercoup can be have subdural hematoma = mass of clotted blood (like bruise)
that forms between dura mater and arachnoid after head injury
- White matter damage can occur due to twisting of the brain within the skull in response to blow
- Pressure exerted on brain because of welling of injured tissues can cause damages or
interruptions in normal function
- Post-concussion syndrome = set of symptoms that follow concussion for period of days-years t
headaches, cognitive deficits, emotional changes, etc.
o Cognitive deficits = lack of concentration, reduction in processing speed, deficits in
higher-order cognitive functions (memory, attention)
o Physical symptoms = headache
o Emotional changes = depression, irritability, etc.
o Persistence of PCS correlated with damage in brain structures t white matter = corpus
callosum and fornix, and gray matter = upper brainstem, base of frontal lobes, medial
temporal lobes
- Repeated mild head injuries can still be damaging
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