Free radicals have been implicated in a number of degenerative conditions, from natural aging to Alzheimer's disease. Glutamate receptors are protein molecules that helps gate the flow of ions across a nerve cell's membrane. The receptors are normally activated by aspartate and glutamate. In amnesic shellfish poisoning, domoic acid acts as an excitotoxin that very strongly activates some of these receptors, preventing their proper functioning. A material that contains many small cavities interconnected with pores of precisely uniform size.
Zeolites are an example.
Molecular sieves adsorb molecules that are small enough to pass through their pore systems- especially water. They are often used as drying agents, and to separate large molecules from smaller ones in preparatory work and in exclusion chromatography. Neurotransmitters are molecules that are used to carry signals from one neuron to another. One neuron releases the neurotransmitter near another neuron's receptors. The neurotransmitter diffuses across the gap between the neurons and locks into a receptor site on the surface of the downstream neuron.