Integumentary System Chapter 6 (BIOL 1110) Fall 2024 PDF

www.udst.edu.qa Chapter 06 The Integumentary System ANATOMY & PHYSIOLOGY The Unity of Form and Function TENTH EDITION KENNETH S. SALADIN © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC...

www.udst.edu.qa Chapter 06 The Integumentary System ANATOMY & PHYSIOLOGY The Unity of Form and Function TENTH EDITION KENNETH S. SALADIN © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. Skin & Membranes 1. Classify, compare the structure of, and give examples of each type of body membrane. 2. Describe the structure and function of the epidermis and dermis. 3. List and briefly describe each accessory organ of the skin. 4. List and discuss the five primary functions of the integumentary system. Skin & Membranes 5. List and briefly describe the three most common types of skin cancer. 6. Classify burns and describe how to estimate the extent of a burn injury. Body Membranes The term membrane refers to a thin, sheetlike structure that may have many important functions in the body. Classification of body membranes – Epithelial membranes Composed of epithelial tissue and an underlying layer of connective tissue – Connective tissue membranes Composed largely of various types of connective tissue  Epithelial Membranes 2- Serous membranes: Simple squamous epithelium on a connective tissue basement membrane – Types Parietal layer: Line walls of body cavities Visceral layer: Cover organs found in body cavities – Examples Pleura: Parietal and visceral layers line walls of thoracic cavity and cover the lungs Peritoneum: Parietal and visceral layers line walls Epithelial Membranes Serous membranes – Diseases Pleurisy: Inflammation of the serous membranes that line the chest cavity and cover the lungs Peritonitis: Inflammation of the serous membranes in the abdominal cavity that line the walls and cover the abdominal organs Epithelial Membranes 3- Mucous membranes  Line body surfaces that open directly to the exterior  Produce mucus, a thick secretion that keeps the membranes soft and moist  The areolar tissue (fibrous connective tissue) component of a mucous membrane is called the lamina propria.  The lamina propria forms a bridge that connects the epithelium to underlying structures.  The term mucocutaneous junction is used to describe the area where the skin and mucous membranes meet. Histology of Mucous Membrane Access the text alternative for slide images. Figure 5.33a 11  Epithelial Membranes Mucous membranes are wet membranes with a connection to the exterior. Serous membranes line the ventral body cavity. The cutaneous membrane is a thick, dry, water-resistant membrane. Figure 3.19 Membranes Connective Tissue Membranes Do not contain epithelial components Produce a lubricant called synovial fluid Examples are the synovial membranes in the spaces between joints and in the lining of bursal sacs The Skin Integumentary Structure and Function Figure 4.1 Functional Organization of the Integumentary System Structures of the Integumentary System Structures that are part of the integument. Skin. Hair. Nails. Glands.  Introduction Inspection of the skin, hair, and nails is significant part of a physical exam Skin is the most vulnerable organ – Exposed to radiation, trauma, infection, and chemicals – Receives more medical treatment than any other organ system Dermatology—scientific study and medical treatment of integumentary system 18 Integumentary Structure and Function The integument covers the entire body surface, including the anterior surfaces of the eyes and tympanic membranes (eardrums) at the ends of the external auditory canals. At the nostrils, lips, anus, urethral opening, and vaginal opening the integument turns inward, meeting the mucous membranes lining the respiratory, digestive, urinary, and reproductive tracts, respectively.  Skin Epidermis: Superficial layer of epithelial tissue. Dermis: Deep layer of connective tissue. Structural strength. Subcutaneous tissue. Integumentary Structure and Function Figure 4.2 Components of the Integumentary System Epidermis Outermost and thinnest primary layer of skin Composed of several layers of stratified squamous epithelium Avascular; nourished by diffusion from capillaries of the papillary layer of the dermis Stratum germinativum: Innermost layer of cells that continually reproduce; new cells move toward the surface As cells approach the surface, they are filled with a tough, waterproof protein called keratin; eventually cells flake off Stratum corneum: Outermost layer of keratin-filled cells Epidermis a) ©Victor Eroschenko; (b) ©McGraw-Hill Education Inc,/Al Telser,  Layers of the Epidermis Table 4.1 Epidermal Layers Figure 4.3 Structure of the Epidermis  Layers of The Epidermis Beginning at the basal lamina and traveling toward the outer epithelial surface ,we find : the stratum germinativum the stratum spinosum the stratum granulosum the stratum lucidum the stratum corneum. Epidermal Cells There are four cell types in the epidermis: Keratinocytes: most cells. Produce keratin for strength. Melanocytes: contribute to skin color. Melanin produced by these cells then transferred to keratinocytes. Same number of melanocytes in all people. Langerhans cells: are fixed macrophages ,part of the immune system. Merkel cells: detect light, touch, and superficial pressure.  Thick and thin skin Most of the body is covered by thin skin. Only four layers are present because the stratum lucidum is typically absent. Thick skin on the palms of the hands may be covered by 30 or more layers of keratinized cells. As a result, the epidermis in these locations exhibits all five layers and may be as much as six times as thick as the epidermis covering the general body surface. Thick and Thin Skin Figure 4.4 Thin and Thick Skin Dermal-epidermal Junction Specialized area between two skin layers Small bumps called dermal papillae help stabilize the junction Blisters are caused by breakdown of union between cells or primary layers of skin  Dermal-epidermal Junction Epidermal ridges: The stratum germinativum layer forms epidermal ridges that extend into the dermis, increasing the area of contact between the tow regions. Projections from the dermis toward the epidermis, called dermal papillae. Ridges on the palms and soles increase the surface area of the skin and increase friction. Ridge shape are genetically determined. Those of each person are unique and do not change in the course of a lifetime.  Skin Color The color of the epidermis is due to a combination of : 1- the dermal blood supply. 2- variable quantities of two pigments: carotene and melanin. Dermal blood supply: When the circulatory supply is temporarily reduced, the skin becomes pale. During a sustained reduction in circulatory supply, the blood in the superficial vessels loses oxygen and the hemoglobin changes color to a much darker red tone. seen from the surface, the skin takes a bluish color called cyanosis.  Skin Color 2 Cyanosis: blue color caused by decrease in blood oxygen content. Erythema: red color caused by increased blood flow.  Skin color Epidermal pigment content: Carotene is an orange- yellow pigment can be converted to vitamin A, which is required for epithelial maintenance and the synthesis of visual pigments by the photoreceptors of the eye. Carotene normally accumulates inside keratinocytes, and becomes especially evident in the dehydrated cells of the stratum corneum and in the subcutaneous fat. Melanin Transfer to Keratinocytes Dermis Deeper and thicker of the two primary skin layers and composed largely of connective tissue Upper papillary layer of dermis characterized by parallel rows of tiny bumps called dermal papillae Ridges and grooves in dermis form pattern unique to each individual – Basis of fingerprinting – Improves grip for tool use and walking Dermis Deeper reticular layer of dermis filled with network of tough, interlacing, collagenous, and stretchable elastic fibers – Number of elastic fibers decreases with age and contributes to wrinkle formation – Dermis also contains nerve endings, muscle fibers, hair follicles, sweat and sebaceous glands, and many blood vessels Cleavage Lines Cleavage (tension) lines: elastic and collagen fibers oriented in some directions more than in others. Important in surgery. If incision parallel to lines, there is less gapping, faster healing, less scar tissue. If skin is overstretched, stretch marks occur. The Dermis and Subcutaneous Layer Figure 4.2 Components of the Integumentary System  Dermal Organization and the Subcutaneous Layer Figure 4.7 The Structure of the Dermis and the Subcutaneous tissue Deep to skin. Also called hypodermis. Consists of loose connective tissue with collagen and elastic fibers. Types of cells. Fibroblasts. Adipose cells. Macrophages. Contains about one-half of body’s adipose tissue. Functions as. Energy source. Insulation. Padding. Accessory Organs of the Skin Hair Nails Skin receptors Hair  Hair is a nonliving keratinized structure that extends beyond the surface of the skin in most areas of the body.  98% of the 5 million hairs on the body are not on the head.  Arrector pili is specialized smooth muscle that produces “goose bumps” and causes hair to stand up straight  Accessory Structures Hair follicles and hair: Hair growth requires epidermal tube-like structure called hair follicle Hair growth begins from hair papilla Hair root lies hidden in follicle and visible part of hair called shaft Figure 4.9a Accessory Structures of the Structure of a Hair and Its Follicle b: Ed Reschke/Stone/Getty Images Access the text alternative for slide images. Figur e 6.8 48  Hair Texture and Color Color due to pigment granules in the cells of the cortex Brown and black hair is rich in eumelanin Red hair has high concentration of pheomelanin Blond hair has an intermediate amount of pheomelanin and very little eumelanin Gray and white hair have little or no melanin; air present in medulla Texture related to cross-sectional shape of hair Straight hair is round Wavy hair is oval Curly hair is relatively flat 51 The Basis of Hair Color and Texture (a-d): Joe DeGrandis/Ken Saladin Access the text alternative for slide images. Figur e 6.9 52 Structure of Nails Skin Receptors Specialized nerve endings: Make it possible for skin to act as a sense organ Lamellar corpuscle (Pacini corpuscle): Capable of detecting pressure Tactile corpuscle (Meissner corpuscle): Capable of detecting light touch Skin Receptors  Glands in the Skin Figure 4.12 A Classification of Exocrine Glands in the Skin  Skin Glands Sweat or sudoriferous glands – Types Eccrine (merocrine) sweat glands – Most numerous, important, and widespread of the sweat glands – Produce perspiration or sweat, which flows out through pores on skin surface – Numerous in palms and soles. – Function throughout life and assist in body heat regulation Apocrine sweat glands – Found primarily in the skin in the axilla (armpit) – Active at puberty. – Larger than eccrine glands – Thicker secretion: organic compounds that are odorless but, when acted upon by bacteria, may become odiferous. Skin Glands Sebaceous glands – Secrete oil for the hair and skin – Holocrine (death of secretory cells). – Grow where hairs grow – Tiny ducts open into hair follicles – Prevents drying and may inhibit bacteria. – Sebum secretion increases during adolescence Sebaceous Glands.  Other Glands Ceruminous glands: Earwax (cerumen). Composed of a combination of sebum and secretion from ceruminous. Function- In combination with hairs, prevent dirt and insects from entry. Mammary glands: modified apocrine sweat glands that produce milk. Functions of the Skin Protection; first line of defense against: – Infection by microbes – Ultraviolet rays from sun – Harmful chemicals – Cuts and tears Temperature regulation – Skin can release almost 3000 calories of body heat per day Mechanisms of temperature regulation – Regulation of sweat secretion – Regulation of flow of blood close to the body surface  Functions of the Skin Protection. Against abrasion Against microorganisms and other foreign substances. Glandular secretions skin contains cells of the immune system. Melanin against UV radiation. Hair on head is insulator and protection against light, and from abrasion. Eyebrows keep sweat out of the eyes; eyelashes protect eyes from foreign objects. Hair in nose and ear against dust, bugs, etc. Nails protect ends of digits, self defense. Acts as barrier to diffusion of water. Heat Exchange In the Skin Functions of the Skin Sense organ activity – Skin functions as an enormous sense organ – Receptors serve as receivers for the body, keeping it informed of changes in its environment Excretion – Body rids itself of wastes – Excess vitamins, drugs, and hormones can be excreted onto the skin by sweat Synthesis of vitamin D – Occurs when skin is exposed to ultraviolet light – Vitamin D is critically important to good health  Functions of the Skin Vitamin D Production. Begins in skin; aids in Ca2+ absorption. Vitamin D (calcitriol): hormone. Stimulates uptake of Ca2+ and PO42- from intestines. People in cold climates and those who cover the body can be deficient, but calcitriol can be absorbed through intestinal wall. Sources: dairy, liver, egg yolks, supplements.  Functions of the Skin Excretion. Removal of waste products from the body. Sweat: water, salt, urea, ammonia, uric acid. Insignificant when compared with kidneys. Aging and the Integumentary System Figure 4.16 The Skin during the Aging Process  Effects of Aging on the Integumentary System Skin more easily damaged because epidermis thins and amount of collagen decreases. Skin infections more likely. Wrinkling occurs due to decrease in elastic fibers. Skin becomes drier. Decrease in blood supply causes poor ability to regulate body temperature. Functioning melanocytes decrease or increase; age spots. Sunlight ages skin more rapidly.  Effects of Sunlight on Skin Ages skin more rapidly. Normal elastic fibers replaced by interwoven mat of elastic-like material. Number of collagen fibers decreases. Impaired ability for keratinocytes to divide. (a) Courtesy of A. M. Kligman, Professor of Dermatology, University of Pennsylvania School of Medicine, Philadelphia, PA; (b) ©Edward Curtis of Library of Congress Courtesy of A. M. Kligman, Professor of Dermatology, University of Pennsylvania School of Medicine, Philadelphia, PA. Skin Cancer Types – Kaposi sarcoma (KS) – Squamous cell carcinoma – Basal cell carcinoma – Malignant melanoma Causes – Genetic predisposition – Sun’s ultraviolet (UV) radiation damages skin cell deoxyribonucleic acid (DNA), causing mistakes during mitosis Skin Cancer Lesions Kaposi Sarcoma (KS) Caused by Kaposi sarcoma–associated herpes virus (KSHV) Purple papules on skin surface, which quickly metastasize internally Squamous cell carcinoma Common type of skin cancer Slow growing Lesions begin as painless, hard, raised nodules Will metastasize Basal cell carcinoma Most common type of skin cancer Originates in cells at base of epidermis, often on upper face Lesions begin as small raised areas that erode in center, bleed, and crust over Less likely to metastasize than other skin cancer types Malignant Melanoma Most serious form of skin cancer May develop from benign, pigmented moles or excess UV radiation Incidence in the United States is increasing ABCDE rule of self-examination (Table 6-1) Warning Signs of Malignant Melanoma Asymmetry Border Color Diameter Evolving 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 6-9) in adults – Body is divided into 11 areas of 9% each – Additional 1% located around genitals The “Rule of Nines” Courtesy Barbara Cousins. Classification of Burns First-degree (partial-thickness) burns – Only the surface layers of epidermis involved Second-degree (partial-thickness) burns – Involve the deep epidermal layers and always cause injury to the upper layers of the dermis Classification of Burns Third-degree (full-thickness) burns – Characterized by complete destruction of the epidermis and dermis – May involve underlying muscle and bone – Risk of infection is increased Fourth-degree (full-thickness) burns – Extends below subcutaneous tissue and reaches muscle or bone – May occur as result of high-voltage electrical burns  Classification of Burns (3 of 3) Copyright © 2020 by Elsevier Inc. 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