Burns Classification and Treatment

Study Notes

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

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 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

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

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 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

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 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