The Human Body in Health and Illness 4
The Human Body in Health and Illness, 4 th edition Barbara Herlihy Chapter 7: Integumentary System and Body Temperature
Lesson 7 -1 Objectives • List six functions of the skin. • Define stratum germinativum and stratum corneum. • Describe the two layers of the skin epidermis and dermis. • List the two major functions of the subcutaneous layer. 2
Functions of the Skin • Serves as mechanical barrier – Harmful out, water and electrolytes in • Protects internal structures • Participates in the immune response – When skin broken dendritic cells alert immune system so it can fight infection. • Acts as a gland for vitamin D synthesis – With exposure to sunlight Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 3
Functions of skin continued • Performs sensory role – Detects information about the environment. • Helps regulate body temperature • Performs excretory function – Excretes water, salt, and small amounts of wastes, such as urea. Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 4
Structure of the Skin • Layers – Epidermis – Dermis – Subcutaneous – Accessory structures • Hair, nails, glands Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 5
Epidermis: Outer Layer • Layers of the epidermis – Stratum germinativum (deeper); cells continuously dividing and moving toward surface – Stratum corneum (surface layer); composed of dead, flattened cells that slough off • Keratinization: The protein keratin makes skin cells hard, flat, and water resistant. • Insensible perspiration: perspiration that evaporates before it is perceived as moisture. Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 6
Dermis • Lies under and supports the epidermis • Sits on the subcutaneous layer or hypodermis • Embedded with accessory structures – Includes blood vessels that nourish epidermis Striae (stretch marks) – small tears in the skin due to excessive stretching. Read “The Skin Tells a Story” pp. 96 -97 http: //www. dermtv. com/difference-betweencalluses-and-corns Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 7
Subcutaneous Layer: Hypodermis • Tissue that lies beneath skin • Highly vascularized • Two main roles: – Its fat insulates body from extreme temperature changes. – Its connective tissue anchors the skin to underlying structures. Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 8
Skin, Drugs, and Chemicals • Skin can absorb many chemicals. • Drug delivery systems: • Hypodermic injections • Transdermal(across the skin) patches • Intradermal injections (allergy testing) • Topical applications • Danger of absorption of toxins Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 9
Skin Color • Determined by genes, physiology, and sometimes pathology • Dark pigment: Melanin – Secreted by melanocytes in the epidermis – Melanocyte malfunctions: Albinism(lack of pigment), vitiligo(loss of pigment in certain areas), moles(concentrated melanin) – Malignant melanoma – skin cancer • Yellow pigment: Carotene – Presence of melanin overshadows carotene’s tint in most people. Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 10
Skin Color (cont’d. ) • Physiological changes: – Blushing: Blood vessel dilation – Pallor: Blood vessel constriction • Pathological changes: – Cyanosis or bluish tint: Poor oxygenation – Jaundice or yellowing: Bilirubin deposition – Bronzing: Melanin overproduction – Ecchymosis: Black and blue bruising Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 11
Accessory Structures: Hair • Functions: Detect insects, protect eyes, keep dust out of lungs • Hormones affect growth. • Melanin influences color. • Hair arises in epidermis. • Cosmetic role – Alopecia – hair loss – Hirsutism – excessive hair growth Arrector pili: muscle cells attached to hair follicle Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 12
Accessory Structures: Nails • Protect tips of fingers and toes from injury • Condition affected by oxygenation of blood supply, trauma, and nutritional deficiencies • Read bullets in nails section p. 100 Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 13
Accessory Structures: Glands • Sebaceous glands: – Oil glands – Secrete sebum and in fetus vernix caseosa – Blackhead, pimple, cradle cap • Sudoriferous – Sweat glands Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 14
Sudoriferous Glands • Apocrine glands: Usually associated with hair follicles; more active at puberty – Respond to emotional stress – pheromones • Eccrine glands: Critical for temperature regulation, not associated with hair follicles – Sensible prespiration • Types of modified sweat glands: – Mammary glands: Secrete milk – Ceruminous glands: Secrete ear wax (cerumen) Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 15
Lesson 7 -2 Objectives • Explain four processes by which the body loses heat. • Describe how the skin helps regulate temperature. Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 16
Body Temperature: Key Terms • Core temperature: The inner parts of the body • Shell temperature: The surface areas of the body • Thermoregulation: Balance of heat production and heat loss • Normal temp. ranges from 97 -100 degrees F • Hypothermia: excessive decrease in body temp • Hyperthermia: excessive increase in body temp Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 17
Heat Production • Metabolism: basis of body temperature • Blood disperses heat throughout the body. • Most heat is produced by muscles, the liver, and endocrine glands. • Affected by food consumption, hormones, disease, and physical activity Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 18
Heat Loss • Sites: Skin (80%), lungs, and excretory products (20%) • Types: – Radiation: heat leaves object to the surrounding air through electromagnetic waves – Conduction: heat transfer through contact – Convection: heat loss due to warm fluid currents – Evaporation: water absorbing heat to change to a gas Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 19
Temperature Regulation • Hypothalamus – Heat lost by: • Dilation of blood vessels • Sweating – Heat conserved by • Shivering • Blood vessel constriction • Less sweat Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 20
Temperature Regulation: Neonates -Newborns • Lose more heat than they produce – Large surface area – Large bald head – Less insulation – Must rely on nonshivering thermogenesis: metabolism of brown adipose tissue (BAT) • Have limited capacity to dissipate heat Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 21
Issues in Temperature Regulation • Hyperthermia: Syncope(loss of consciousness), cramps, heat exhaustion, heat stroke • Hypothermia: Slowed metabolism, fibrillation(rapid, irrigular, and unsychronized contractions of muscle fibers) Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 22
Burns: Classified by Depth • Partial thickness burns – First-degree: red, painful and slightly swollen – Second-degree: includes blisters • Full-thickness burn – Third-degree: painless Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 23
Burns: Classified by Extent • “Rule of nines” • Eschar: dead piece of skin produceded by a thermal burn – Acts like a tourniquet – Breeds bacteria – Secretes toxins Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 24
Skin Care • All ages: – Reduce exposure to UV radiation. • Especially in older adults: – Skin dries out more easily; retain moisture by limiting excessive bathing and use of soap. – Thinner skin bruises more easily and does not insulate as well. – Read pp. 105 -107 Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 25
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