Chapter 5 The Integumentary System ST 110 Mosby items and derived items 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 2 Objectives Describe the importance of skin lines in surgery Name the layers of the skin Describe the function of the skin Describe the growth process of skin Describe the blood, lymph, and nerve supply of skin Describe functions of the subcutaneous layer Mosby items and derived items 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Objectives Continued Describe the anatomy of hair and nails Describe the function of melanocytes Describe the two types of of glands located in the skin and their function Explain the difference between eccrine and apocrine sweat glands Describe how sweat aids in regulating body temperature Mosby items and derived items 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Objectives Continued Describe the ceruminous glands Name and describe the three types of burns Explain the difference between autograft, allograft, and xenograft Describe the Rule of Nines Explain the various effects of aging on the skin Describe the three types of wound healing Mosby items and derived items 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Objectives Continued Describe the stages of primary wound healing Describe the suture that is best used on the skin and subcutaneous layers Mosby items and derived items 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 6 Functions of the skin Protectionfirst line of defense against: Infection by microbes Infection by microbes Ultraviolet rays from sun Ultraviolet rays from sun Harmful chemicals Harmful chemicals Cuts and tears Cuts and tears Mosby items and derived items 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 7 THE SKIN Functions of the skin (cont.) Temperature regulation Skin can release almost 3000 calories of body heat per day Skin can release almost 3000 calories of body heat per day Mechanisms of temperature regulation Regulation of sweat secretion Regulation of blood flow close to the body surface Sense organ activity Skin functions as an enormous sense organ Skin functions as an enormous sense organ Receptors serve as receivers for the body, keeping it informed of changes in its environment Receptors serve as receivers for the body, keeping it informed of changes in its environment Mosby items and derived items 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Structure of Skin and Subcutaneous Layer Epidermis- ectoderm (outer layer) composed of stratified squamous keratinizing epithelium Dermis- mesoderm (middle layer) composed of connective tissue Subcutaneous (hypodermis)- layer beneath the dermis Mosby items and derived items 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Epidermis Keratinocytes- stratified squamous cells keratinized epithelial cells. Skin lines in surgery are traced during incisions: promote healing prevent contracture preserve function hide the scar Mosby items and derived items 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Epidermis Continued Stratum germinativum- deepest layer of epidermis Stratum basale- connects epidermis to the basement layer Stratum spinosum- several layers thick and appear to be connected by spinelike processes Stratum granulosum- a few cells thick and consists of two/three layers of flattened cells Mosby items and derived items 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Epidermis Continued Stratum lucidium- thin and transparent one cell thick flat cells Stratum corneum- outermost layer epidermis Mosby items and derived items 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Thick and Thin Skin Layers Thick- found on palms of hands and soles of feet (areas exposed to friction and weight bearing). Friction ridges are easily visible and thick tissue is easier to suture. Thin- decreased layer of epidermis and thin layer of keratin. No friction ridges visible. Mosby items and derived items 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Subcutaneous Tissue Subcutaneous (Subq) Layer- connects the dermis to the underlying structures, provides insulation from the cold, protects/cushions internal organs and bony prominences. Mosby items and derived items 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Blood and Lymph Vessels and Nerve Suppply Blood vessels- Contain arteries that supply blood to the skin divide, branch, and then subdivide reaching the subcutaneous tissue and dermis areas. Vasodilation of blood vessels occurs to cool the body. Lymph vessels- network of small branches in the superior layer of the dermis Mosby items and derived items 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Blood, Lymph, and Nerve Supply Nerves- innervate skin and travel upward through the deep layer of the dermis superiorly forming mesh networks. Reactive hyperemia- increase in the amount of blood in an area of the body in which the circulation has been reestablished after a short period of occlusion. Ex tourniquet use Mosby items and derived items 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Skin Pigmentation The distribution and concentration of melanin in the epidermis effect the variations of skin color of individuals and races. All individuals have relatively the same amount of melanocytes in their skin. The more melanin produced, the darker the skin Albinism- condition resulting from the absence of skin pigmentation. Mosby items and derived items 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Immune Response to the Skin Langerhans cells- They are formed in the bone marrow and found throughout the epidermis and they attack cancer cells. Mosby items and derived items 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Appendages Hair- functions to prevent debris and perspiration from harming body and somewhat prevents heat escape. Hair follicles- invaginations of the epidermis found in the subcutaneous layer. Hair bulb- area at the base of the hair follicle where hair growth begins. Hair color- dictated by the type of melanin present. Meibomian glands- largest sebaceous glands found in the eyelids. Blackheads-excess sebum production which clogs and gets trapped in a gland opening and oxidizes. Arrector pili muscles- muscle contraction causes hair to stand on end. Mosby items and derived items 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 19 Ceruminous Glands Ceruminous Glands- modified type of sebaceous gland located in the dermis in the auditory canal of the ear. Cerumen- A yellowish secretion AKA ear wax. Mosby items and derived items 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 20 Mosby items and derived items 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 21 Mosby items and derived items 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 22 Nails Accessory structures of the skin (cont.) Nails Produced by epidermal cells over terminal ends of fingers and toes Produced by epidermal cells over terminal ends of fingers and toes Nail Body- visible part of nail Nail Body- visible part of nail Nail Matrix- portion of cutis beneath the body Nail Matrix- portion of cutis beneath the body Nail Groove- area from which the nail grows outward from a transverse curved area. Nail Groove- area from which the nail grows outward from a transverse curved area. Nail bed-thin layer of epidermis attached to the undersurface of the nail plate, may change color with change in blood flow. Nail bed-thin layer of epidermis attached to the undersurface of the nail plate, may change color with change in blood flow. Lunula- white crescent at the proximal end of the nail Lunula- white crescent at the proximal end of the nail Mosby items and derived items 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 23 Mosby items and derived items 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 24 Mosby items and derived items 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 25 Burns Classification of burns, indicating depth of burn First-degree (partial-thickness) burnsonly the surface layers of epidermis involved First-degree (partial-thickness) burnsonly the surface layers of epidermis involved Second-degree (partial-thickness) burns- varying degrees of the dermis Second-degree (partial-thickness) burns- varying degrees of the dermis Third-degree (full-thickness) burnscharacterized by complete destruction of the epidermis and dermis, and the upper portion of the subcutaneous layer Third-degree (full-thickness) burnscharacterized by complete destruction of the epidermis and dermis, and the upper portion of the subcutaneous layer Eschar- destruction of all layers of skin leave tissue black in color and composed primarily of collagen. Fourth-degree- char burns Fourth-degree- char burns Mosby items and derived items 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 26 Burns Burns Treatment and recovery or survival depend on total area involved and severity or depth of the burn Body surface area is estimated using the rule of nines (Figure 5-8) in adults Body is divided into 11 areas of 9% each Body is divided into 11 areas of 9% each Additional 1% located around genitals Additional 1% located around genitals Mosby items and derived items 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 27 Mosby items and derived items 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 28 BURN SYMPTOMS First Degree Redness and pain. No blisters, no scarring (sunburn) Second Degree Extreme pain, blisters, swelling, redness. Usually no scar Third Degree Shock, possibly pain nerves destroyed, dehydration, eschar Mosby items and derived items 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 29 WOUND HEALING There are three types of wound healing: first intention, second intention, third intention FIRST INTENTION - Three (3) Phases Phase 1 Lag or inflammatory phase. Begins immediately after injury, lasts 3 to 5 days. There is swelling, pain, redness, heat, loss of function. Scab forms on surface of skin. Neutrophils and macrophages migrate to the area. Fibroblasts begin reforming nonepithelial tissue. Mosby items and derived items 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 30 Phase 2 Proliferation phase. Begins on 3 rd or 4 th day and continues for about 20 days. Fibroblasts close the wound edges and secrete collagen which forms into fibers to provide the wound about 30% of its original tensile strength. A new capillary network is established. Mosby items and derived items 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 31 First Intention Phase 3 Phase 3 Maturation or Differentiation Phase Begins on the 14 th day post-op and ends when wound is healed. Wound contraction is completed around 21 days post-op. The collagen reaches maximum density. Leaves a mature scar called a cicatrix. Mosby items and derived items 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 32 Wound Healing Second Intention Occurs when a wound fails to heal by first intention. Appropriate for large wounds when edges cannot be approximated by suture, large wounds on which undue tension will placed, and infected wounds. Wound is left open to heal from the bottom. As the wound heals, the space is filled with granulation tissue. Wound closure occurs by contraction. These wound closures tend to be weak and form a wide, irregular-shaped scar. Herniation is common. Mosby items and derived items 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 33 Wound Healing Third Intention Used for the management of contaminated wounds including traumatic wounds Healing occurs when the edges of the granulated surface are approximated Surgeon leaves the wound open to heal by second intention for four to six days. When the wound is infection free, it is closed with suture or staples to finish healing by first intention. Mosby items and derived items 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 34 SUTURING SKIN AND SUB-Q LAYERS Skin wounds heal slowly and are slow to regain their tensile strength. Nonabsorbable suture is preferred to provide a longer period of support to the wound Monofilament suture usually causes less tissue reaction. Skin suture is removed between 3 and 10 days post-op Mosby items and derived items 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 35 Subcutaneous Layers Contd Sub-q is primarily fat and water and has little tensile strength and does not tolerate suturing well Many surgeons do suture this layer to prevent dead space, accumulation of fluid and/or air which delay wound healing. Absorbable suture is preferred. Closure of sub-q tissue minimizes the skin scar. Mosby items and derived items 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Functions of the Skin Thermoreceptors- respond to temperature Nociceptors- respond to painful irritants Mechanoreceptors- respond to pressure or stretching Mosby items and derived items 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Afferent Nerves Free nerve endings- no Schwann cells, found in the deep layers of the epidermis and the dermal papillary layer. Encapsulated nerve endings- have Schwann cells, inclusive of pacinian corpuscles which have a role in deep pressure sensation. Mosby items and derived items 2008 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 38 Functions of the Skin As skin ages, it changes in both appearance and physiology. Age spots result of oxidation Thickness of dermis decreases less elastic Loss of sub-q fat leads to sagging, wrinkling Elderly are more sensitive to the cold Lymphocytes decrease wounds heal slower Oil secretion decreases skin becomes dry and brittle