Plaques and Tangles
Amyloid Plaques (Click To Enlarge)
Amyloid Plaques Damage Brain Cells
Amyloid is a naturally occurring protein in the human body and brain. During Alzheimer's, normal Amyloid groups suffer from a structural change which disrupts normal functioning.
One abnormal amyloid group causes other healthy amyloid groups near it to also mutate, eventually they form large groups of amyloid deposits, called plaques or fibrils.
These plaques have a toxic affect on brain cells and cause the brain lesions characteristic of Alzheimer's. These plaques can be seen in the image above as the brown cloud-like substance damaging the neuron cells.
Tau Tangles (Click To Enlarge)
Tau Tangles Prevent Brain Cells From Communicating
Tau is another naturally occurring protein in the human body and brain. Its primary purpose in the brain is to stabilize the axons of brain cells. The axon is the part of the cell through which electrical signals travel.
In Alzheimer's disease, tau proteins suffer from a structural change which causes them to pair with other threads of tau. The tau, now tangled with other tau, is no longer able to stabilize the brain cell's axon; the axon subsequently unravels and ceases to exist.