Final answer:
Neurofibrillary tangles are aggregates of hyperphosphorylated tau proteins within neurons that contribute to neuronal degeneration in Alzheimer's disease. They lose their microtubule stabilizing function, resulting in disrupted neuronal function and cell death. These tangles, along with beta-amyloid plaques, are key pathological features of Alzheimer's.
Step-by-step explanation:
Neurofibrillary Tangles and Alzheimer's Disease
Neurofibrillary tangles are pathological features of Alzheimer's disease and are composed of abnormally phosphorylated tau proteins. Normally, tau helps stabilize microtubules in neurons. However, in Alzheimer's disease, tau becomes hyperphosphorylated, losing its ability to bind microtubules, leading to their disassembly. Subsequently, the malformed tau proteins aggregate into neurofibrillary tangles within the neuronal cell bodies. Immunostained micrographs, which highlight these tangles, show them stained deep purple due to the use of antibodies specific to tau protein. These tangled protein clumps are implicated in the disruption of neuronal function and contribute to the degeneration and death of brain cells in people with Alzheimer's.
In addition to neurofibrillary tangles, extracellular beta-amyloid (Aß) plaques are another hallmark of Alzheimer's disease, which may influence glutamate transmission, leading to excitotoxicity and neuronal damage. The accumulation of these plaques and tangles disrupt the normal function of brain cells, leading ultimately to the memory loss, cognitive decline, and dementia characteristic of Alzheimer's disease.