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.
Compare with permanent hardness and water hardness . The component of total water hardness that can be removed by boiling the water. A substance that can cause deformities in embryos. Dioxin is a teratogen. Compare with water softener .