Burns Classification and Treatment

Layers of the Skin

• The skin and its accessory structures make up the integumentary system
• The skin is the largest organ by weight, composed of several tissue types, and is also called the cutaneous membrane
• The skin has two main layers: epithelial tissue overlying connective tissue
• The epidermis is the outer layer, composed of stratified squamous epithelium
• The dermis is the inner layer, thicker than the epidermis, and is composed of connective tissue with collagenous and elastic fibers, muscle, blood, and nervous tissue
• The subcutaneous layer (hypodermis) is beneath the dermis, an insulating layer of areolar and adipose connective tissue that is not considered part of the skin

Special Cells of the Epidermis

• Dendritic (Langerhans) cells are found in the stratum spinosum, act as phagocytes, and protect skin and underlying tissues from infection
• Tactile (Merkel) cells are found in the stratum basale, act as sensory receptors for light touch, and are associated with sensory nerve endings in the dermis
• Melanocytes are found in the stratum basale, produce the pigment melanin, and absorb UV light from sunlight to provide skin color

Skin Color

• Skin color results mainly from the melanin pigment
• Hereditary factors influence skin color, including the amount of melanin produced and its distribution
• Environmental factors, such as sunlight and UV light, affect skin color
• Physiological factors, such as oxygenation and blood vessel dilatation, also influence skin color

Skin Glands

• Sebaceous glands are holocrine glands associated with hair follicles, produce sebum, and keep hair and skin soft and waterproof
• Sweat glands are widespread in the skin, originate in the deeper dermis or hypodermis, and have different types, including eccrine, apocrine, and specialized sweat glands
• Eccrine sweat glands respond to elevated body temperature and are most numerous
• Apocrine sweat glands respond to emotions and pain and are found in the axillary and groin areas

Skin Functions

• The skin is a protective barrier against harmful substances, UV radiation, microorganisms, and water loss
• The skin contains sensory receptors for touch, pressure, temperature changes, and pain
• The skin excretes some wastes and produces Vitamin D
• The skin regulates body temperature through sweating, blood flow changes, and heat loss mechanisms

Heat Loss Through the Skin

• Heat loss through the skin occurs through radiation, conduction, convection, and evaporation
• Radiation is the primary method of heat loss, where infrared heat rays travel from the warmer skin to the cooler environment

Body Temperature Regulation Mechanisms

• When body temperature rises, thermoreceptors signal the hypothalamus, causing vasodilation of dermal blood vessels, sweat gland activation, and vasoconstriction of deep blood vessels
• When body temperature falls, thermoreceptors signal the hypothalamus, causing vasoconstriction of dermal blood vessels, vasodilation of deep blood vessels, and sweat gland inactivation

Burns

• Burns are classified by extent of tissue damage, including superficial, partial-thickness, and full-thickness burns
• Superficial burns injure only the epidermis, heal in days to weeks, and do not scar
• Deep, partial-thickness burns destroy the epidermis and some dermis, may blister, and heal varies with severity of burn and stem cell survival
• Full-thickness burns destroy the epidermis, dermis, and accessory structures, require skin grafts or substitutes, and often require extensive treatment