The depth of a burn determines its severity. First degree burns damage the outer layer of skin (epidermis) and cause pain, redness and swelling (erythema). Second degree burns damage the epidermis and the inner layer, the dermis, causing erythema and blistering. Damage from third degree burns extend into the hypodermis, causing destruction of the full thickness of skin with its nerve supply (numbness). Third degree burns leave scars and may cause loss of function and/or sensation.

First degree burns produce only reddening of the skin. Second degree burns produce blistering, as seen here.

Mild, or first degree burns cause only reddening of the epidermis (outer layer of the skin), as seen in this photograph. Second degree burns cause blistering and extend into the dermis (lower layer of skin). Third degree burns cause tissue death through the dermis and affect underlying tissues.

Burns to the airway can be caused by inhaling smoke, steam, superheated air, or toxic fumes, often in a poorly ventilated space. Airway burns can be very serious since the rapid swelling of burned tissue in the airway can quickly block the flow of air to the lungs.

The skin is the largest organ of the body. The skin and its derivatives (hair, nails, sweat and oil glands) make up the integumentary system. One of the main functions of the skin is protection. It protects the body from external factors such as bacteria, chemicals, and temperature.

First degree burns affect the outer layer of the skin, causing pain, redness, and swelling.

Second-degree burns affect both the outer and underlying layer of the skin, causing pain, redness, swelling, and blistering.

Third-degree burns extend into deeper tissues, causing brown or blackened skin that may be numb.

Browse through illustrations for Minor burn - first aid - series