when the entire heart, both of the atria and ventricles, is relaxed.
epithelium with numerous layers of cells.
emitting (or giving off) radiation energy, which is harmful to living organisms.
deep, narrow holes drilled into the earth to reach the ground water in aquifers.
a tough substance made from a modified polysaccharide that contains nitrogen. It is the main...
the process in which micro-organisms, such as yeast, convert sugars into alcohol under anaerobic...