The brain of an alzheimer's victim displays plaques, which are and tangles, which are

Scientists can also glimpse the awful effects of Alzheimer's disease when they look at brain tissue beneath the microscope:

Alzheimer's tissue has numerous fewer nerve cells and synapses than a well brain.

Scientists are not absolutely sure what causes cell death and tissue deficiency in the Alzheimer's brain, but plaques and tangles are key suspects.

the answer that best describes the relative refractory period in the neuron is the resting membrane potential is restored, but concentrations of sodium and potassium are not restored to their original state.

the refractory period is the time during which another stimulus given to the neuron will not lead to a second potential. thus, because na+ channels are inactivated during this time, additional depolarizing stimuli do not lead to new action potentials.  

read more on -