Emergency Medical Services are provided in Ann Arbor as out-of-hospital cute care, transport to a place where more specialized care is available, and other medical transport to patients with illnesses and injuries which prevent the patient from transporting themselves. This is given with the aim of providing urgent medical care to a satisfactory level. If it is a publicly owned EMS, it is operated by the Ann Arbor municipality, which may be the responsibility of the local or the state government. For small communities, they are staffed by volunteers. Private EMS organizations also exists in some parts of the country. Usually, the physicians or the surgeon does not respond directly to the emergency, unless the patient is a low-weight infant, or there is necessity of an emergency cardiac bypass surgery, or a mass casualty situation. There is, however, medical control by indirect supervision of a medical director, or board-certified physician who oversees the policies and protocols of a particular EMS system. In America, the model is to bring the patient to the hospital rather than the other way around. While there is no federal or state stanard for response time, they do sometimes exist in the form of contractual obligations between communities and EMS provider organizations. Ideal response time is less than ten minutes, however, this is rarely achieved. The ambulances used for EMS can be of varying types depending on the specific needs.