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.
The Great Barrier Reef contains, like many other reefs, its own Eco-cycle per se. The reason that it's so fragile is because the slightest rise in temperatures can make the reef uninhabitable for may of the aquatic creatures there.   When people say reef, they imply coral reef.. Corals, and other things like coralline algae, are what form reefs.     Corals are Cnidarians, the same ph â¦ ylum as anemones and jellyfish. Being a Cnidarian, a coral contains nematocysts to sting and capture prey in their tentacles.