Definition. The normal concentration of sodium in the blood plasma is 136-145 mM. Hyponatremia occurs when sodium falls below 130 mM. Plasma sodium levels of 125 mM or less are dangerous and can result in seizures and coma. Description. Sodium is an atom, or ion, that carries a single positive charge.
reef1. 1  a ridge of rocks or sand, often of coral debris, at or near the surface of the water. 2  Mining. a lode or vein.
Coral is a colony of tiny animals that have porous limestone skeletons which can be used for bone repair in humans. Coral reefs are home to about 10% of all the fish that people eat. Coral reefs cover about one-fiftieth of the ocean floor, but about one-quarter of all marine species make reefs their home.