Depolarizationof the axon hillock to threshold results in the generationand propagation of an action potential. The action poten-tial is a transient change in the membrane potential charac-terized by a gradual depolarization to threshold, a rapid ris-ing phase, an overshoot, and a repolarization phase.
Ecology. Staphylococcus aureus is a normal inhabitant of the skin and mucous membranes in the nose of a healthy human, while S. epidermidis inhabits only the skin of healthy humans. S. aureus is infectious to both animals and humans.he Staphylococcus aureus genome, which is the most common species amoung the genome projects, is about 2.8 Mega-base pairs long with approximately 2,600 open reading frames, comprising 84.5% of the genome.
Streptococcus mutans (Fig 1.) is a spherical shaped, gram positive bacteria belonging to the Streptcoccaceae family.All bacteria from this family are gram positive, facultatively anaerobic and have complex nutritional requirements.. mutans is well suited to living in the human oral cavity. It tolerates temperatures ranging from 18-40 degrees celcius and will readily metabolize carbohydrates. The high carbohydrate diet of humans and many animals makes this area a suitable habitat.