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7 Nervous - Nervous System I Dementia a Significant in destruction of neuronal tissue and neurons b Over 50 of individuals over 80 have some form

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Nervous System I. Dementia a. Significant ↑ in destruction of neuronal tissue and neurons b. Over 50% of individuals over 80 have some form of dementia c. The older you get the chances of developing dementia increase c.i. Forgetful moments in elderly -1 st sign d. ApoE4 gene - associated with risk factor for Alzheimer’s d.i. 40% of population have this gene II. General Info a. Basic structure of brain a.i. White matter - myelinated portion of cells (axons and dendrites) a.ii. Gray matter - cell bodies a.iii. Neurons - conduct current; communicate chemically with adjacent cells. a.iii.1. Cell bodies (axons, somas) do not typically regenerate a.iii.2. Single axon - myelinated or nonmyelinated; will eventually branch into hundreds of other nonmyelinated branches a.iii.2.a. Myelin - fatty sheath; increases velocity of conduction a.iii.2.b. Terminal axons- constantly regenerated a.iii.3. Soma - location of nucleus, cell organelles a.iii.4. Neurotubules & neurofilaments- allow for materials to be transferred from soma to terminal axons and vice versa a.iii.4.a. Made of Tau protein - sensitive to phosphorylation. a.iii.4.b. Antrograde movement- from soma to axon a.iii.4.c. Retrograde movement- from axon to soma a.iv. Neuroglia (about 400 billion found in brain) a.iv.1. Astrocytes - provide assistance by providing nutrients to neurons, provide growth factors, allow for synaptic genesis to occur(creating new synapses) a.iv.2. Oligodendrocytes - similar to schwanne cells; make myelin a.iv.3. Ependymal cells - make CSF a.iv.4. Microglia - macrophages found in brain; immune cells III. Changes in brain as we age a. Decrease in size a.i. Females =age 18-19 a.ii. Makes= age 19-20 a.iii. Hodge was first to study change in size of brain b. Cortex b.i. 25-50% loss of associated neurons in frontal cortex of brain b.ii. Frontal cortex is important in distinguishing us from other animals b.ii.1. deals with logic, deductive reasoning, abstract thinking, memory c. Substantia Nigra c.i. 30-40% decrease in number of neurons found in substantia nigra c.ii. Do not see changed resulting from this loss until you reach 70% loss d. Hippocampus d.i. After menopause there is a 5% loss every decade of neurons found in hippocampus d.ii. Some stem cells can stop this loss but still see overall loss d.iii. Alzheimer’s - after 5 years of diagnosis, complete destruction of neurons in hippocampus e. Amygdala e.i. Main function is the mechanism of fear and communicates with frontal cortex
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f. ↑ number of neuroglia cells f.i. Theory behind it is to help support the remaining cells and make more synapses to compensate for the loss of neurons g. Gyri - help increase surface area of brain; As we age, the gyri undergo atrophy h. Sulci - As we age, the sulci widen i. Macroscopically i.i. Excessive increase in lipofucsin i.i.1. 10% volume of neurons due to lipofucsin i.i.2. Consequences- interference with cellular function, especially electrical currents i.ii. Increase in fatty vacuoles i.iii. Decrease in number of mitochondria, endoplasmic reticulum, nissl bodies
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This note was uploaded on 02/25/2012 for the course CHEM 1341 taught by Professor Compton during the Fall '08 term at Texas State.

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7 Nervous - Nervous System I Dementia a Significant in destruction of neuronal tissue and neurons b Over 50 of individuals over 80 have some form

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