Healing of Wounds and Burns & the Aging of Skin Chapter 6 Sections 5 & 6Chapter 6 Sections 5 & 6

Objectives Describe wound healing Distinguish among the types of burns, including a description of healing with each type Summarize life-span changes in the integumentary system

The Healing Process Inflammation is a normal response to injury or stress Blood vessels in affected tissues dilate and become more permeable, allowing fluids to leak into damaged tissues Inflamed skin may become reddened, swollen, warm and painful to touch However, the dilate vessels provide more nutrients and oxygen to the injured site, which aids in healing The specific events of the healing process depend on the nature and extent of the injury

Shallow Cuts If a cut in the skin is shallow, epithelial cells along its margin are stimulated to divide more rapidly than usual The newly formed cells fill the gap

4 Stages of Healing for Deep Wounds Hemostasis Inflammation Proliferation Remodeling

Deeper Cuts If the cut extends into the dermis or subcutaneous fat layer, blood vessels break and the released blood forms a clot in the wound (hemostasis) A clot consists of mainly the fibrous protein fibrin, blood cells and platelets trapped in the protein fibers Tissue fluids seep into the area and dry The blood clot and the dried tissue fluids form a scab that covers and protects the underlying tissues Epithelial cells proliferate beneath the scab, bridging the wound Fibroblasts migrate into the injured area and secrete collagenous fibers to the bind the edges of the wound (proliferation) Cells are stimulated to divide and regenerate the damaged tissue (remodeling)

Healing Continued Blood vessels extend beneath the scab Macrophages remove dead cells and other debris Eventually all the damaged tissue is replaced and the scab falls off If the wound is deep, extensive production of collagenous fibers may form an elevation above the normal epidermal surface, called a scar

Burns Three types of burns: 1 st degree 2 nd degree 3 rd degree

1 st Degree Burns Also known as superficial partial-thickness burns Occur when the epidermis only is injured Skin becomes dry, warm and reddened (erythema) Mild edema may occur Surface layer of the skin may peel off a few days later Healing takes a few days to weeks but no scaring occurs Examples: minor sunburn

2 nd Degree Burns Also known as deep partial-thickness burns Occur when some of the epidermis and some of the underlying dermis is destroyed Fluid escapes from the damaged dermal capillaries, forming blisters The injured area becomes moist and firm It can vary in color from dark red to waxy white Examples: exposure to hot objects, hot liquids, flames or burning clothing

2 nd Degree Burn Healing Healing depends on the stem cells that are associated with accessory structures of the skin Hair follicles, sweat glands and sebaceous glands survive this injury because they extend into the dermis During healing, the stem cells divide and their daughter cells grow out onto the surface of the dermis, spread over it, and differentiate as new epidermis Scar tissue doesn’t develop unless infection occurs

3 rd Degree Burns Also known as full-thickness burns Occur when epidermis, dermis and the accessory structures of the skin are destroyed The injured skin becomes dry and leathery It can vary in color from red to black to white Examples: immersion in hot liquids or prolonged exposure to hot objects, flames, or corrosive chemicals

Burn Treatments 1 st degree Soak in cool water for a few minutes Apply antibiotic cream Take ibuprofen or acetaminophen 2 nd degree Soak in cool water for several minutes Apply antibiotic cream Cover with non-stick bandage and change daily Take ibuprofen or acetaminophen

Burn Treatments 3 rd degree Seek medical attention in an emergency room Try to elevate burn above the heart Once in the ER the following steps may be taken: Securing your airway Sedation Removing necrotic skin Blood transfusions IV fluids IV antibiotics Surgery Skin grafts

How Skin Ages Aging skin affects appearance, temperature regulation, and vitamin D formation Aging effects to the skin: Epidermis thins and appears scaly Age spots or liver spots appear, which are patches of pigment formed from the oxidation of fats and the production of oxygen free radicals Dermis is reduced as creation of collagen and elastin slows The combination of a shrinking dermis and the loss of fat in the subcutaneous layer results in wrinkling and sagging of the skin Reduction of fibroblasts delay wound healing Decrease in oil from sebaceous glands dries the skin Slowed melanin production whitens hair Hair growth slow, hairs thin and the number of follicles decreases