Chapter 007
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Transcript of Chapter 007
The Human Body in Health and Illness, 4th 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 skinepidermis
and dermis.• List the two major functions of the
subcutaneous layer.
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Functions of the Skin
• Serves as mechanical barrier• Protects internal structures • Participates in the immune response• Acts as a gland for vitamin D synthesis• Performs excretory function• Performs sensory role• Helps regulate body temperature
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Inc. All rights reserved. 3
Structure of the Skin
• Layers– Epidermis– Dermis– Subcutaneous – Accessory
structures
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Inc. All rights reserved.4
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.
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Inc. All rights reserved.5
Dermis
• Lies under and supports the epidermis• Sits on the subcutaneous layer or hypodermis• Embedded with accessory structures– Includes blood vessels that nourish epidermis
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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.
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Inc. All rights reserved.7
Skin, Drugs, and Chemicals
• Skin can absorb many chemicals.• Drug delivery systems:
• Hypodermic injections• Transdermal patches• Intradermal injections (allergy testing)• Topical applications
• Danger of absorption of toxins
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Inc. All rights reserved.8
Skin Color
• Determined by genes, physiology, and sometimes pathology
• Dark pigment: Melanin– Secreted by melanocytes in the epidermis– Melanocyte malfunctions: Albinism, vitiligo, moles
• Yellow pigment: Carotene– Presence of melanin overshadows carotene’s tint
in most people
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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
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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
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Accessory Structures: Nails
• Protect tips of fingers and toes from injury• Condition affected by oxygenation of blood
supply, trauma, and nutritional deficiencies
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Accessory Structures: Glands
• Sebaceous glands:– Oil glands– Secrete sebum and in
fetus vernix caseosa
• Sudoriferous– Sweat glands
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Sudoriferous Glands
• Apocrine glands: Usually associated with hair follicles; more active at puberty
• Eccrine glands: Critical for temperature regulation
• Types of modified sweat glands:– Mammary glands: Secrete milk– Ceruminous glands: Secrete ear wax (cerumen)
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Inc. All rights reserved.14
Lesson 7-2 Objectives
• Explain four processes by which thebody loses heat.
• Describe how the skin helps regulate temperature.
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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
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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
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Heat Loss
• Sites: Skin (80%), lungs, and excretory products (20%)
• Types:– Radiation– Conduction– Convection– Evaporation
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Temperature Regulation
• Hypothalamus– Heat lost by: • Dilation of blood
vessels• Sweating
– Heat conserved by• Shivering• Blood vessel
constriction• Less sweat
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Temperature Regulation: Neonates
• 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
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Issues in Temperature Regulation
• Hyperthermia: Syncope, cramps, heat exhaustion, heat stroke• Hypothermia: Slowed metabolism, fibrillation
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Burns: Classified by Depth
• Partial thickness burns– First-degree– Second-degree
• Full-thickness burn– Third-degree
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Burns: Classified by Extent
• “Rule of nines”
• Eschar– Acts like a
tourniquet– Breeds
bacteria– Secretes
toxins
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Inc. All rights reserved.23
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.
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Inc. All rights reserved.24