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. This induces a change in the downstream neuron. Compare with temporary hardness and water hardness . Chlorides also contribute to permanent hardness.