LECTURE 5 INTEGUMENTARY SYSTEM Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. Learning Objectives Describe the layers of the epidermis and the cells that compose them. Compare the composition of the papillary and reticular regions of the dermis. Explain the basis for different skin colors. Contrast the structure, distribution, and functions of hair, skin glands, and nails. Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. The Integumentary System Skin Accessory structures of the skin Functions of the skin Aging and the integumentary system Diseases Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. SKIN Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. The Integumentary System The integumentary system is composed of the skin, hair, oil and sweat glands, nails, and sensory receptors. Structurally, the skin consists of 2 main parts: 1. The superficial, thinner portion, which is composed of epithelial tissue, is the epidermis. 2. The deeper, thicker portion is the dermis, made of dense irregular connective tissue. Deep to the dermis, but not part of the skin, is the subcutaneous (hypodermis). Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. The Integumentary System The epidermis is composed of keratinized stratified squamous epithelium. It contains four principal types of cells: Keratinocytes – 90% of the epidermal cells arranged in four or five layers and produce the protein keratin. Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. The Integumentary System Melanocytes – 8% of the cells and produce the pigment melanin. Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. The Integumentary System Intraepidermal macrophages (Langerhans cells) participate in immune responses. Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. The Integumentary System Tactile epithelial cells – detect touch sensations. Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. The Integumentary System Epidermis 4 Strata: Thin Skin Stratum basale Stratum spinosum Stratum granulosum (thin) Stratum corneum Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. The Integumentary System Epidermis 5 Strata: Thick Skin Stratum basale Stratum spinosum Stratum granulosum Stratum lucidum (thick) Stratum corneum Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. The Integumentary System Stratum basale Deepest layer Composed of a single row of cuboidal or columnar keratinocytes Some cells are stem cells Keratin protects the deeper layers from injury Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. The Integumentary System Stratum spinosum Consists of numerous 8-10 layers of keratinocytes some cells shrink and pull apart when prepared for microscopic exam. Thus, they appear thorn-like spines Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. The Integumentary System Stratum granulosum 3-5 layers of flattened keratinocytes that undergoing apoptosis Presence of darkly staining granules of a protein called keratohyalin Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. The Integumentary System Stratum granulosum With membraneenclosed lamellar granules – which fuse with the plasma membrane and release a lipid-rich secretions Water-repellent sealant Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. The Integumentary System Stratum lucidum Present only in the thick skin such as the fingertips, palms, and soles Consists of 4-6 layers of flattened clear, dead keratinocytes (contain large amount of keratin and thickened plasma membrane) Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. The Integumentary System Stratum corneum Consists of 25-30 layers of flattened, dead keratinocytes (thin) 50 or more layers (thick skin) Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. The Integumentary System Newly formed cells in the stratum basale are slowly pushed to the surface. As the cells move from one epidermal layer to the next, they accumulate more and more keratin, a process called keratinization. Eventually the keratinized cells slough off and are replaced by underlying cells. Dandruff – excessive amount of keratinized cells shed from the skin of the scalp Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. The Integumentary System The dermis, is the deeper part of the skin and is composed mainly of connective tissue containing collagen and elastic fibers. Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. The Integumentary System The superficial (papillary region) part of the dermis makes up about one-fifth of the thickness of the total layer and consists of areolar connective tissue containing fine elastic fibers. Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. The Integumentary System Its surface area is greatly increased by small, fingerlike projections called dermal papillae, touch receptors (Meissner corpuscles) and free nerve endings. Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. The Integumentary System The deeper part of the dermis (reticular region), which is attached to the subcutaneous layer, consists of dense irregular connective tissue containing bundles of collagen and some coarse elastic fibers. Adipose cells, hair follicles, nerves, oil glands, and sweat glands are found between the fibers. Melanin, hemoglobin, and carotene are three pigments that impart a wide variety of colors to skin. The amount of melanin causes the skin’s color to vary from pale yellow to reddish-brown to black. Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. Components of the Skin Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. ACCESSORY STRUCTURES OF THE SKIN Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. The Integumentary System Accessory structures of the skin that develop from the epidermis of an embryo— hair, glands, and nails. Hair and nails protect the body Sweat glands help regulate body temperature Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. The Integumentary System Hairs, or pili, are present on most skin surfaces except the palms, palmar surfaces of the fingers, soles, and plantar surfaces. is a thread of fused, dead, keratinized epidermal cells that consists of a shaft (most superficial), a root (into the dermis) and follicle. Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. Hair Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. Hair Associated with hairs are bundles of smooth muscle called arrector pili and sebaceous glands or oil glands. Sebaceous glands are usually connected to hair follicles; they are absent in the palms and soles. produce sebum, which moistens hairs and waterproofs the skin. Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. Hair Arrector pili extends from the superficial dermis of the skin to the dermal root sheath around the side of the hair follicle. Under physiological or emotional stress, such as cold or fright, autonomic nerve endings stimulate the muscles to contract, which pulls the hair shafts perpendicular to the skin surface. “goose bumps” or “gooseflesh” because the skin around the shaft forms slight elevations Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. Hair The color of hair is due to melanin. Gray hair occurs with a decline in melanin. White hair results from accumulation of air bubbles in the hair shaft. Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. Hair Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. Accessory Structures of the Skin Glands – are single or groups of epithelial cells that secrete a substance. Sebaceous Sudoriferous (sweat) Ceruminous Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. Accessory Structures of the Skin Sebaceous glands secrete an oily substance called sebum keeps hair from drying out prevents excessive evaporation of water keeps the skin soft, and inhibits certain bacteria Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. Accessory Structures of the Skin Ceruminous glands present in the outer ear canal is a yellowish secretion called cerumen or earwax. Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. Accessory Structures of the Skin Two types of sudoriferous glands: Apocrine sweat glands – found mainly in the skin of the axilla (armpit), groin, areolae (pigmented areas around the nipples) of the breasts, and bearded regions of the face in adult males. simple, coiled tubular glands but have larger ducts and lumens Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. Accessory Structures of the Skin Two types of sudoriferous glands: Eccrine sweat glands – most prevalent sweat glands distributed throughout most of the body, especially in the skin of the forehead, palms, and soles simple, coiled tubular gland Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. NAILS Nails are hard, dead, keratinized epidermal cells covering the terminal portions of the fingers and toes. The principal parts of a nail are the nail body, free edge, nail root, lunula, cuticle, and nail matrix. The proximal portion of the epithelium deep to the nail root is called the nail matrix. Cell division of the matrix cells produces new nails. Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. Nails Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. Copyright © 2015 John Wiley & Sons, Inc. All rights reserved. FUNCTIONS OF THE SKIN Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. The Integumentary System The 5 major functions of the skin: 1. Body temperature regulation. The skin contributes to the homeostatic regulation of body temperature by liberating sweat at its surface and by adjusting the flow of blood in the dermis. 2. Protection. Keratin in the skin protects underlying tissues from microbes, abrasion, heat, and chemicals. Lipids released by lamellar granules inhibit evaporation of water from the skin surface. Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. The Integumentary System 3. Cutaneous sensations. These include tactile sensations (touch, pressure, vibration, and tickling), thermal sensations (warmth and coolness) and pain. 4. Excretion and absorption. 5. Synthesis of vitamin D. Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. AGING AND THE INTEGUMENTARY SYSTEM Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. The Integumentary System Most of the age-related changes begin at about age 40 and occur in the proteins in the dermis. Collagen fibers in the dermis begin to decrease in number, stiffen, break apart, and disorganize into a shapeless, matted tangle. Elastic fibers lose some of their elasticity, thicken into clumps, and fray, an effect that is greatly accelerated in the skin of smokers. Fibroblasts, which produce both collagen and elastic fibers, decrease in number, the result, the skin forms crevices known as wrinkles. Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. Normal Mole and Malignant Melanoma Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. Burns Copyright © 2015 John Wiley & Sons, Inc. All rights reserved. Burns: The Rule-of-Nines Copyright © 2015 John Wiley & Sons, Inc. All rights reserved. Medical Terms Abrasion. An area where skin has been scraped away. Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. Medical Terms Blister. A collection of serous fluid within the epidermis or between the epidermis and dermis, due to short-term but severe friction. Bulla refers to a large blister. Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. Medical Terms Callus. An area of hardened and thickened skin that is usually seen in palms and soles and is due to persistent pressure and friction. Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. Medical Terms Cold sore. A lesion, usually in an oral mucous membrane, caused by type 1 herpes simplex virus (HSV) transmitted by oral or respiratory routes. Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. Medical Terms Comedo. A collection of sebaceous material and dead cells in the hair follicle and excretory duct of the sebaceous (oil) gland. Usually found over the face, chest, and back, and more commonly during adolescence. Also called a blackhead. Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. Medical Terms Contact dermatitis (der-ma-T-I -tis; dermat= skin; -itis = inflammation of) Inflammation of the skin characterized by redness, itching, and swelling and caused by exposure of the skin to chemicals that bring about an allergic reaction, such as poison ivy toxin. Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. Medical Terms Contusion (kon-TOO-shun; contundere = to bruise) Condition in which tissue deep to the skin is damaged, but the epidermis is not broken. Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. Medical Terms Corn. A painful conical thickening of the stratum corneum of the epidermis found principally over toe joints and between the toes, often caused by friction or pressure. Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. Medical Terms Cyst (SIST = sac containing fluid) A sac with a distinct connective tissue wall, containing a fluid or other material. Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. Medical Terms Eczema (EK-ze-ma; ekzeo- = to boil over) An inflammation of the skin characterized by patches of red, blistering, dry, extremely itchy skin Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. Medical Terms Frostbite. Local destruction of skin and subcutaneous tissue on exposed surfaces as a result of extreme cold. In mild cases, the skin is blue and swollen and there is slight pain. Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. Medical Terms Hemangioma (hē-man′-jē-O- -ma; hem- = blood; -angi- = blood vessel; -oma =tumor) Localized benign tumor of the skin and subcutaneous layer that results from an abnormal increase in the number of blood vessels. Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. Medical Terms Hives. Reddened elevated patches of skin that are often itchy. Most commonly caused by infections, physical trauma, medications, emotional stress, food additives, and certain food allergies. Also called urticaria (ūr-ti-KAR-ē-a) Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. Medical Terms Keloid (KE--loid; kelis = tumor) An elevated, irregular darkened area of excess scar tissue caused by collagen formation during healing. Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. Medical Terms Keratosis (ker′-a-TO- -sis; kera- = horn) Formation of a hardened growth of epidermal tissue, such as solar keratosis, a premalignant lesion of the sun-exposed skin of the face and hands. Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. Medical Terms Laceration (las-er-A- -shun; lacer- = torn) An irregular tear of the skin. Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. Medical Terms Lice Contagious arthropods that include two basic forms. Head lice are tiny, jumping arthropods that suck blood from the scalp. They lay eggs, called nits, and their saliva causes itching that may lead to complications. Pubic lice are tiny arthropods that do not jump; they look like miniature crabs. Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. Medical Terms Papule (PAP-ūl; papula = pimple) A small, round skin elevation less than 1 cm in diameter. One example is a pimple. Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. Medical Terms Pruritus (proo-RI -tus; pruri- = to itch) Itching, one of the most common dermatological disorders. Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. Medical Terms Ringworm Tinea corporis – body Tinea cruris – groin Tinea pedis – feet (athlete’s feet) Tine unguium – fingers Copyright © 2018 John Wiley & Sons, Inc. All rights reserved. Medical Terms Wart. Mass produced by uncontrolled growth of epithelial skin cells; caused by a papillomavirus. Copyright © 2018 John Wiley & Sons, Inc. All rights reserved.
