Exam 3 Chapter 10 1 10 3 Brain Damage 1 What are tumors What is metastasis What are the differences between miningiomas and gliomas Tumors cancer are masses of cells growing in an uncontrolled manner Meningioma tumor encased in meninges 20 of brain tumors usually benign so they are unlikely to spread throughout the body They are dangerous because the pressure exerted on brain by tumor can cause necrosis of neural tissue It is relatively easy to spot on CT scans and remove through surgery Glioma tumor derived from glial cells usually malignant damage surrounding neural tissue difficult to completely remove tends to metastasize spread not all gliomas are malignant 2 What are the differences between a hemorrhage and ischemia What are the 3 types of ischemia How does ischemia lead to hypertoxicity Hemorrhage bleeding damages surrounding tissue often due to burst of aneurysm Ischemia disruption of blood flow Thrombosis clot forms in brain vasculature Embolism clot forms elsewhere dislodges moves to brain Arteriosclerosis walls of blood vessels thicken constricting blood flow 3 What are the infarct and penumbra and which does rehabilitation attempt to save see results of Nudo 1996 Infarct region of dead or dying tissue Penumbra surrounds infarct but has potential to recover Nudo induced ischemic lesion in hand area of monkey motor cortex provided experimental group with rehabilitative training compared to control group more recovery of penumbra of hand use 4 What are the two types of closed head injuries Contusions involve damage to circulatory system result in hemorrhage and hematoma bruise often occur on opposite side of brain from strike called contrecoup injury Concussions no contusion or structural damage observed but temporary loss or disturbance of consciousness usually some retro and anterograde amnesia for events surrounding incident 5 Epilepsy What are its symptoms what seems to be the cause what different types can occur what animal model mimics this disorder A neurological disorder characterized by spontaneously recurring seizures specifically seizures due to abnormal brain activity often motor seizures but not always Can be caused by viruses neurotoxins tumors concussions or be congenital Over 70 genes involved in epilepsy have been identified neurons become hyperexcitable Classified as partial or generalized Partial simple sensory or motor or both complex often associated with temporal lobe compulsive behaviors people suffering a complex seizure may appear conscious throughout but will often have little memory of the events during the seizure Generalized seizures tonic clonic seizures rigidity and tremors absence seizures loss of consciousness cessation of behavior Epileptic auras cues that can provide useful info can take many forms such as hallucination very helpful because they can signal where the seizure is starting in addition to giving warning Kindling model of epilepsy series of periodic brain stimulations eventually elicit convulsions will not generate spontaneous seizures unless kindles hundreds of times 6 Parkinson s What are its symptoms what seems to be the cause Movement disorder of middle and old age affects about 0 5 of population Tremor at rest is the most common symptom dementia is not generally seen Associated with the degeneration of the substantia nigra these neurons release dopamine to the striatum of the basal ganglia no single cause some genetic factors neurotoxin exposure Deep brain stimulation of subthalamic nucleus reduces symptoms but its effectiveness slowly declines over months or years MPTP model of PD designer drug produced the symptoms of parkinson s contained MPTP which causes cell loss in the substantia nigra like that seen in PD animal studies provide the means to identify potentially useful treatments for PD 7 Huntington s What are its symptoms what seems to be the cause Rare progressive motor disorder of middle and old age with a strong genetic base Huntingin gene cell death in striatum of basal ganglia Begins with fidgetiness and progresses to jerky movements of entire limbs and severe dementia death usually occurs within 15 years first symptoms not usually seen until age 40 8 Multiple Sclerosis What are its symptoms what seems to be the cause A progressive disease that attacks CNS myelin leaving areas of hard scar tissue sclerosis an autoimmune disease Periods of remission are common Symptoms include visual disturbances muscle weakness numbness tremor and loss of motor coordination ataxia 9 Alzheimer s What are its symptoms what 3 characteristics define it and which is thought to be the cause what animal model mimics this disorder Most common cause of dementia one s likelihood of developing it increases with age early stages are characterized by confusion and a selective decline in memory definitive diagnosis is only possible at autopsy Three defining characteristics neuron loss neurofibrillary tangles threadlike tangles of protein in the neural cytoplasm and amyloid plaques clumps of scar tissue composed of degenerating neurons and the protein amyloid Genetic research on early onset AD supports the amyloid first hypothesis Transgenic mouse models of AD only humans and a few related primates develop amyloid plaques transgenic genes of another species have been introduced genes accelerating human amyloid synthesis are introduced into mice plaque distribution comparable to that in AD unlike humans no neurofibrillary tangles Exam 3 Chapter 10 4 10 5 Brain Repair 1 Following axotomy what types of degeneration can occur Axotomy axon is cut in central nervous system likely to lead to death of neuron and even spread to other neurons Anterograde degeneration distal portion of axon away from soma dies Retrograde degeneration proximal portion of axon near soma dies proximal axon may regenerate if it can make a new synapse before death Transneuronal degeneration neuron that lost axon may die neuron that lost input may die neurons that synapsed with dead neurons may die 2 What are the differences between apoptosis and necrosis Necrosis quick passive cell death in response to injury leads to inflammation Apoptosis slow programmed cell death prevents damage to surrounding cells 3 What factors promote regeneration in the peripheral nervous system Neural regeneration generally does not occur in the CNS of adult mammals but more probable in PNS Doesn t seem to be inherent to neurons Schwann cells generally promote axon regrowth Oligodendrocytes
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