RALEIGH — It doesn't take single-digit temperatures for the human body to be susceptible to hypothermia.

"Obviously our extremities get cold when we go outside, but the internal parts of the body maintain constant temperature," said Dr. Tony Morris, a UNC emergency physician. "With hypothermia, that core body temperature goes down."

Our normal body temperature is fixed at 98.6 degrees. When it drops to 95 degrees or lower, it is a medical emergency. The body responds by trying to raise the core temperature, causing shivering.

This shifts blood flow, raising the body's core temperature. This, of course, puts you at risk for frostbite in the fingers and toes. A person suffering from these symptoms can then go unconscious.

When that happens, warming the body as quickly and safely as possible is the top priority.

"If they're not very cold, we do simple things like warm blankets and that sort of thing," Morris said. "If they're extremely cold, you can do a number of things to warm the internal fluids -- even cardiopulmonary bypass."

The best line of defense: stay indoors. If you must go outside, do take measures to protect yourself by wearing: