section epub:type=”chapter” id=”c0085″ role=”doc-chapter”> The integumentary system consists of the hair, nails, and skin and performs many functions that influence the perianesthesia nursing interventions in the postanesthesia care unit (PACU). Although the skin has many functions, the most important is to act as a barrier between the internal and external environments. The integumentary system is the body’s largest organ and first line of defense against many mechanisms of injury that could cause permanent harm. anatomy; aseptic technique; assessment; burn injuries; epidermis; integumentary; thermoregulation The integumentary system consists of the hair, nails, and skin and performs many functions that influence the perianesthesia nursing interventions in the postanesthesia care unit (PACU). Although the skin has many functions, the most important is to act as a barrier between the internal and external environments. In addition, skin plays an important role in body temperature and fluid regulation, excretion, secretion, vitamin D production, sensation, appearance, and many other functions. The integumentary system is the body’s largest organ and first line of defense against many communicable diseases and mechanisms of injury that could cause permanent harm. In the hospital setting, patients are at risk for many unwanted infections caused by the pathogens and normal flora present in the environment. The objective of this chapter is to provide the reader with the anatomy and physiology of the integumentary system. It will provide background information to assist the perianesthesia nurse in understanding infection control and aseptic technique. There will be an overview of the patient with acquired thermal injury. Greater understanding of the integumentary system will assist the perianesthesia nurse in providing vitally needed care to the patient with a compromised first line of defense. Definitions Desquamation The process by which dead cells are shed at a fairly constant rate. Dermis Corium, or the second layer of the skin. Epidermis Multilayered outer covering of the skin. Frostbite Trauma caused by injury to any body tissue caused by exposure to extreme cold temperatures; usually affects fingers, toes, and the nose. Can result in gangrene. Keratinocytes Generate a barricade against heat, water loss, ultraviolet (UV) radiation, heat, and pathogens. Langerhans cells Also prevent pathogens from getting into your skin and are responsible for topical allergic reactions. Melanocytes Produce skin pigment and may assist in protection from the processes responsible for the development of skin cancer. Integumentary System Skin and cutaneous tissue. The skin, or integument, provides a boundary between the internal and external environments of the body. It is the largest organ of the human body. With aging, the skin becomes thinner with less elasticity and diminished collagen, which, at 75% to 80%, is the largest component of the skin. There is less inflammatory response and integumentary immunity protection with aging. Skin generally accounts for about 15% of the total body weight, or about 6 pounds. The skin is divided into two major layers: the epidermis and the dermis, which includes the hypodermis (Fig. 17.1). Depending on location, skin varies in number of layers and thickness. The soles of the feet and palms of the hands have the thickest skin (approximately 1.5 mm) and have five layers. Eyelids have the thinnest skin (approximately 0.10 mm) and have four layers.1,2 Longitudinal section of skin shows labels (clockwise) as follows: Epidermis, dermis, subcutaneous tissue, connective tissue, arrector pili muscle, hair follicle, nerves, adipose tissue, blood vessels, apocrine sweat gland, eccrine sweat gland, sebaceous gland, melanocyte, stratum germinativum (basal cell layer), stratum corneum (horny cell layer), and hair shaft. The outermost layer of the skin is called the stratum corneum. It is composed of surface lipids, dirt, melanocytes, Langerhans cells, and keratinocytes that are continually sloughing as new ones replace them. The skin completely sheds itself about once every 28 days. The epidermis does not have any blood vessels. Dead cells are shed at a fairly constant rate with a process called desquamation. The epidermis also has keratinizing and glandular appendages. Keratinizing appendages develop into hair and nails; glandular appendages include the sweat, scent, and sebaceous glands. The pigment that determines skin color (e.g., melanin) is also found in the epidermis in organelle structures called melanosomes. Melanosomes are transported to the keratinocytes and surround them. When skin is exposed to the sun or ultraviolet radiation, the quantity of melanosomes increases, providing photoprotection and causing a change in skin color. The innermost layer of epidermis is the stratum basale/germinativum, which contains thin, flat squamous cells, and is the site of origin for squamous cell carcinoma. Squamous cell cancer is more aggressive than basal cell carcinoma and often invades surrounding tissues and lymph glands. It is often found on surfaces of the skin that have the most exposure to the sun. The cells of the lowest, or basal, layer of the epidermis are constantly dividing and producing new epidermal cells. Basal cell cancer develops from this layer. It tends to be slow growing and is the most common skin cancer with a high rate of recurrence. It is usually found in areas of the body with the most sun exposure. The granular layer, or stratum granulosum, contains three or four layers of cells. It is composed of cells called keratinocytes, which undergo a maturation process called keratinization. This process produces lipid granules that form waterproof structures and helps prevent fluid loss and evaporation through the skin into the environment.3 The dermis, or corium, is a layer of connective tissue that lies under the epidermis and above the subcutaneous tissue. It consists of collagen, elastic, and reticular fibers. The dermis also contains blood vessels, nerves, the lymphatics, and smooth muscle. It is responsible for the stretching of skin during movement, sensation, thermoregulation, and protection of underlying tissues as well as being the location that the structures for hair growth are located. Nerve fiber endings are found in both the epidermis and the dermis, sensing touch, temperature, pressure, vibration, and pain.4 The hypodermis, also called the subcutaneous layer or superficial fascia, functions as a shock absorber and heat insulator. Located under the dermis, it comprises fat or adipose tissue, smooth muscle, and adipocytes. These cells store and accumulate necessary fats. The hypodermis is very vascular. The hypodermis acts as a site of energy production and insulation. This area of the body stores fat in characteristic locations: the hips on women and the abdomen in men.1,2 This layer acts as a connector between the skin and the tissues of the bones and muscles. The skin has many functions, the most important of which is to act as a barrier between the internal and external environments. In addition, the skin has an essential role in body temperature and fluid regulation, excretion, secretion, vitamin D production, appearance, biochemical reactions, and immunology. Skin, subcutaneous tissue, and fat in the subcutaneous tissue provide heat insulation for the body. Heat is lost from the body to the surroundings through radiation, conduction, convection, and evaporation (Fig. 17.2).5 Radiation of heat from the body accounts for approximately 60% of total heat loss. In this method, heat is lost in the form of infrared heat waves. Conduction of heat to objects represents approximately 3% of the total heat loss, whereas conduction of heat to the air represents approximately 15% of the total heat loss. When water is carried away from the skin by air currents, convection of heat occurs. Evaporation constitutes approximately 22% of the heat loss. Even without sweating, water still evaporates from the skin and the lungs; this is called insensible loss and totals approximately 600 mL/day.5 A person sits at a table. Heat loses from the person’s body through evaporation (22 percent), conduction to objects (3 percent), conduction to air (15 percent), and radiation (60 percent). Three arrows labeled air currents (convection) point toward arrows indicating heat lost in the form of conduction to air. Heat waves from the body hit the walls and then return to the body. The skin regulates body temperature by conserving heat in a cold environment and lowering the temperature in hot environments through sweating. The physiological functions of sweat glands are thermoregulation, release of waste products, and response to emotional stress.6 The sweat glands are innervated by the sympathetic and parasympathetic nervous systems. When the anterior hypothalamus, in the preoptic area of the brain, is stimulated by excess heat, impulses are sent from this area by way of the autonomic pathways to the spinal cord. From the spinal cord through the sympathetic outflow tracts, the impulses go to the skin all over the body. Sweat secretion is regulated by both the central nervous system and the autonomic nervous system, through neurotransmitters such as acetylcholine (ACh) and norepinephrine (NE). Sweat glands are innervated by cholinergic nerve fibers that secrete ACh, but run in the sympathetic nerves with the adrenergic fibers.5,6 They can be somewhat stimulated by NE and epinephrine, catecholamines functioning as hormones and neurotransmitters that assist with the fight-or-flight response. The sweat gland consists of two portions: a deep subdermal coiled portion that secretes sweat and a duct portion that conducts sweat to the skin. Sweat has a pH of 3.8 to 6.5 and contains sodium, chloride, potassium, calcium, lactic acid, and urea; therefore, sweating is an act of excretion and secretion. There are two types of sweat glands, eccrine and apocrine. Eccrine sweat glands are found over the entire skin surface and produce odorless, colorless secretions which are important in body temperature regulation. Apocrine sweat glands are in direct contact with the hair follicle and found in specific areas of the body, for example, axillae, nipple, and perineal body area. The secretions of these glands interact with skin bacteria which causes body odor.5,6 As noted, the skin protects the body from injurious physical, chemical, electric, thermal, or biological stimuli. Of particular importance to the perianesthesia nurse is the presence of bacteria and viruses on the skin that can cause infection when a patient’s skin barrier is broken. Normal florae of the skin include Staphylococcus, Streptococcus, and Corynebacterium organisms. Diphtheroids are also widely distributed on the skin, especially in moist areas. The normal pH of the skin is an acidic 4 to 6.5 resulting from production of lactic acid and residues of amino acids. This slightly acidic environment serves as a protective mechanism by inhibiting bacterial growth. Diabetic, cardiac, and renal patients tend to have more alkaline skin surfaces, thus they are at higher risk for skin infections.7 When intact, the skin stops unwanted organisms from entering the body and, at the same time, prevents the loss of water, electrolytes, and proteins to the external environment. When the skin is broken (e.g., surgical incision, ulceration, abrasion, rash, venipuncture), the barrier between the internal and external environments is broken, which is why aseptic technique is important whenever a break of the skin is anticipated or has occurred. Because all skin has disease-causing organisms on its surface, skin can never be sterile. Precautions should be taken to reduce the number of pathogenic organisms that may be introduced into a wound. Good hand washing remains the most important activity in the prevention of disease transmission. The development and use of alcohol-based gel hand washing solutions has led to improved rates of hand washing compliance by health care providers. Nonetheless, establishment and availability of these products alone—without associated behavioral modification programs—have proven unsuccessful. Hands should be washed at the very least according to the World Health Organization’s Guidelines (“Five Moments for Hand Hygiene”) using either traditional hand washing techniques or using a sanitizing gel before caring for any patient.8 When hands are visibly soiled, traditional washing should occur (Box 17.1).9 (See Chapter 5 for more information on hand washing and prevention of infection.)
17: The Integumentary System
Abstract
Keywords
Integumentary system anatomy
Epidermis
Dermis
Hypodermis
Integumentary functions
Thermoregulation
Protection
Importance of aseptic technique
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