Copyright © 2005, 2002, 1997, 1992 by Mosby, Inc. All rights reserved. Chapter 6 The Integumentary System and Body Membranes

Copyright © 2005, 2002, 1997, 1992 by Mosby, Inc. All rights reserved. Classification of Body Membranes 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

Copyright © 2005, 2002, 1997, 1992 by Mosby, Inc. All rights reserved. Classification of Body Membranes Epithelial membranes –Cutaneous membrane—the skin –Serous membranes—simple squamous epithelium on a connective tissue basement membrane Types –Parietal—line walls of body cavities –Visceral—cover organs found in body cavities

Copyright © 2005, 2002, 1997, 1992 by Mosby, Inc. All rights reserved. Classification of Body Membranes Examples –Pleura—parietal and visceral layers line walls of thoracic cavity and cover the lungs –Peritoneum—parietal and visceral layers line walls of abdominal cavity and cover the organs in that cavity

Copyright © 2005, 2002, 1997, 1992 by Mosby, Inc. All rights reserved. Classification of Body 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

Copyright © 2005, 2002, 1997, 1992 by Mosby, Inc. All rights reserved. Classification of Body Membranes Mucous membranes –Line body surfaces that open directly to the exterior –Produce mucus, a thick secretion that keeps the membranes soft and moist

Copyright © 2005, 2002, 1997, 1992 by Mosby, Inc. All rights reserved. Classification of Body 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 the bursal sacs

Copyright © 2005, 2002, 1997, 1992 by Mosby, Inc. All rights reserved. The Skin Structure—two primary layers called epidermis and dermis –Epidermis Outermost and thinnest primary layer of skin Composed of several layers of stratified squamous epithelium Stratum germinativum—innermost layer of cells that continually reproduce, and new cells move toward the surface

Copyright © 2005, 2002, 1997, 1992 by Mosby, Inc. All rights reserved. The Skin Structure—two primary layers called epidermis and dermis –Epidermis As cells approach surface, they are filled with a tough, waterproof protein called keratin and eventually flake off Stratum corneum—outermost layer of keratin-filled cells

Copyright © 2005, 2002, 1997, 1992 by Mosby, Inc. All rights reserved. The Skin Structure—two primary layers called epidermis and dermis –Epidermis Pigment-containing layer—epidermal layer that contains pigment cells called melanocytes, which produce the brown pigment melanin –Vitiligo-acquired loss of epidermal melanocytes Blisters—caused by breakdown of union between cells or primary layers of skin Dermal-epidermal junction—specialized area between two primary skin layers

Copyright © 2005, 2002, 1997, 1992 by Mosby, Inc. All rights reserved. The Skin Structure—two primary layers called epidermis and dermis –Dermis Deeper and thicker of the two primary skin layers and composed largely of connective tissue Upper area of dermis characterized by parallel rows of peg-like dermal papillae Ridges and grooves in dermis form pattern unique to each individual (basis of fingerprinting) Deeper areas of dermis filled with network of tough collagenous and stretchable elastic fibers

Copyright © 2005, 2002, 1997, 1992 by Mosby, Inc. All rights reserved. The Skin Structure—two primary layers called epidermis and dermis –Dermis Number of elastic fibers decreases with age and contributes to wrinkle formation –Striae—stretch marks »Stork bite

Copyright © 2005, 2002, 1997, 1992 by Mosby, Inc. All rights reserved. The Skin Structure—two primary layers called epidermis and dermis –Dermis Dermis also contains nerve endings, muscle fibers, hair follicles, sweat and sebaceous glands, and many blood vessels –Birthmarks—malformation of dermal blood vessels »Strawberry hemangioma »Port-wine stain

Copyright © 2005, 2002, 1997, 1992 by Mosby, Inc. All rights reserved. The Skin Appendages of the skin –Hair Soft hair of fetus and newborn called lanugo Hair growth requires epidermal tube-like structure called hair follicle Hair growth begins from hair papilla

Copyright © 2005, 2002, 1997, 1992 by Mosby, Inc. All rights reserved. The Skin Appendages of the skin –Hair Hair root lies hidden in follicle; visible part of hair called shaft Alopecia hair loss Arrector pili—specialized smooth muscle that produces “goose pimples” and causes hair to stand up straight

Copyright © 2005, 2002, 1997, 1992 by Mosby, Inc. All rights reserved. The Skin Appendages of the skin –Receptors Specialized nerve endings—make it possible for skin to act as a sense organ Meissner’s corpuscle—capable of detecting light touch Pacinian corpuscle—capable of detecting pressure

Copyright © 2005, 2002, 1997, 1992 by Mosby, Inc. All rights reserved. The Skin Nails –Produced by epidermal cells over terminal ends of fingers and toes –Visible part called nail body –Root lies in a groove and is hidden by cuticle –Crescent-shaped area nearest root called lunula –Nail bed may change color with change in blood flow

Copyright © 2005, 2002, 1997, 1992 by Mosby, Inc. All rights reserved. The Skin Nails –Onycholysis –Nail pitting –Normal variations in nail structure Longitudinal ridges Pitting

Copyright © 2005, 2002, 1997, 1992 by Mosby, Inc. All rights reserved. The Skin Skin glands –Types Sweat or sudoriferous Sebaceous

Copyright © 2005, 2002, 1997, 1992 by Mosby, Inc. All rights reserved. The Skin Skin glands –Sweat or sudoriferous glands Types –Eccrine sweat gland »Most numerous, important, and widespread of the sweat gland »Produce perspiration or sweat, which flows out through pores on skin surface »Function throughout life and assist in body heat regulation

Copyright © 2005, 2002, 1997, 1992 by Mosby, Inc. All rights reserved. The Skin Skin glands –Sweat or sudoriferous glands Types –Apocrine sweat gland »Found primarily in axilla and around genitalia »Secrete a thicker, milky secretion quite different from eccrine perspiration »Breakdown of secretion by skin bacteria produces odor

Copyright © 2005, 2002, 1997, 1992 by Mosby, Inc. All rights reserved. The Skin Skin glands –Sweat or sudoriferous glands Types –Sebaceous gland »Secrete oil or sebum for hair and skin »Level of secretion increases during adolescence »Amount of secretion regulated by sex hormones »Sebum in sebaceous gland ducts may darken to form a blackhead »Acne vulgaris inflammation of sebaceous gland ducts

Copyright © 2005, 2002, 1997, 1992 by Mosby, Inc. All rights reserved. Functions of the Skin Protection—first line of defense –Against infection by microbes –Against ultraviolet rays from sun –Against harmful chemicals –Against cuts and tears –Skin grafts

Copyright © 2005, 2002, 1997, 1992 by Mosby, Inc. All rights reserved. Functions of the Skin 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

Copyright © 2005, 2002, 1997, 1992 by Mosby, Inc. All rights reserved. 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—disorders of the skin (dermatoses)

Copyright © 2005, 2002, 1997, 1992 by Mosby, Inc. All rights reserved. Skin Lesions Elevated lesions—cast a shadow outside their edges –Papule—small, firm raised lesion –Plaque—large raised lesion –Vesicle—blister –Pustule—pus-filled lesion –Crust—scab –Wheal (hive)—raised, firm lesion with a light center

Copyright © 2005, 2002, 1997, 1992 by Mosby, Inc. All rights reserved. Skin Lesions Flat lesions—do not cast a shadow –Macule—flat, discolored region Depressed lesions cast a shadow within their edges –Excoriation—missing epidermis, as in a scratch wound –Ulcer—craterlike lesion –Fissure—deep crack or break

Copyright © 2005, 2002, 1997, 1992 by Mosby, Inc. All rights reserved. Burns First-degree (partial-thickness) burns— only 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

Copyright © 2005, 2002, 1997, 1992 by Mosby, Inc. All rights reserved. Burns Third-degree (full-thickness) burns (Figure 6-14) characterized by complete destruction of the epidermis and dermis –May involve underlying muscle and bone (fourth-degree) –Lesion is insensitive to pain because of destruction of nerve endings immediately after injury—intense pain is soon experienced

Copyright © 2005, 2002, 1997, 1992 by Mosby, Inc. All rights reserved. Burns Estimating body surface area using the “rule of nines” in adults –Body divided into 11 areas of 9% each –Additional 1% of body surface area around genitals

Copyright © 2005, 2002, 1997, 1992 by Mosby, Inc. All rights reserved. Skin Infections Impetigo—highly contagious staphylococcal infection –Tinea—fungal infection (mycosis) of the skin; several forms occur –Boils—furuncles; staphylococcal infection in hair follicles –Scabies—parasitic infection

Copyright © 2005, 2002, 1997, 1992 by Mosby, Inc. All rights reserved. Vascular and Inflammatory Skin Disorders Decubitus ulcers (bedsores) develop when pressure slows down blood flow to local areas of the skin Urticaria or hives—red lesions caused by fluid loss from blood vessels Scleroderma—disorder of vessels and connective tissue characterized by hardening of the skin; two types: localized and systemic

Copyright © 2005, 2002, 1997, 1992 by Mosby, Inc. All rights reserved. Vascular and Inflammatory Skin Disorders Psoriasis—chronic inflammatory condition accompanied by scaly plaques Eczema—common inflammatory condition characterized by papules, vesicles, and crusts; not a disease itself but a symptom of an underlying condition

Copyright © 2005, 2002, 1997, 1992 by Mosby, Inc. All rights reserved. Skin Cancer Three common types –Squamous cell carcinoma—the most common type, characterized by hard, raised tumors –Basal cell carcinoma—characterized by papules with a central crater; rarely spreads –Melanoma—malignancy in a nevus (mole); the most serious type

Copyright © 2005, 2002, 1997, 1992 by Mosby, Inc. All rights reserved. Skin Cancer The most important causative factor in common skin cancers is exposure to sunlight Kaposi sarcoma, characterized by purple lesions, is associated with AIDS and other immune deficiencies