1. The Human Body in Health and Illness, 4th edition
Barbara Herlihy
Chapter 7:
Integumentary System
and Body Temperature

2. 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.
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3. 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
The skin, the accessory structures, and the subcutaneous tissue form the integumentary system .
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4. Structure of the Skin Layers Epidermis Dermis Subcutaneous
Accessory structures
Oxygen and nutrients diffuse into the lower epidermis from the richly nourished dermis.
In which layers are the blood vessels found?
The blood vessels are found in the dermis and subcutaneous.
Where are the statum germinativum and stratum corneum found?
Both are layers of epidermis; the statrum germinativum is the deeper of the two.
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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.
As the cells of the stratum germinativum divide, they push the older cells toward the surface of the epithelium.
To what do the terms exfoliation and desquamation refer?
These terms describe the sloughing off of the stratum corneum.
What are dander and dandruff?
Individual dead cells are called dander; when clumped together by oil, they are dandruff.
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
What role do the collagen and elastin fibers of the dermis play?
These fibers make the dermis stretchable and strong.
What accessory structures are embedded in the dermis?
The hair, nails, and certain glands are embedded in the dermis.
The sensory receptors that detect pain, temperature, pressure, and touch are also located in the dermis.
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.
Is the subcutaneous layer considered to be part of the skin?
No, it is not.
Why are many drugs injected subcutaneously (SC)?
The hypodermis has a rich supply of blood vessels. The blood vessels absorb the drug and distribute it throughout the body.
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8. 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
What are some drugs that can be given transdermally?
Examples are nitroglycerin and contraceptive patches.
What are some toxins that can be absorbed through the skin?
Examples are pesticides, dry cleaning fluid, acetone, and mercury.
Distinguish between transdermal and topical applications of drugs.
Transdermal applications enter the bloodstream; topical applications remain on the skin’s surface.
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, vitiligo, moles
Yellow pigment: Carotene
Presence of melanin overshadows carotene’s tint in most people
What is the physiological basis of the summer tan?
UV radiation boosts melanin production, beginning with a tan, and potentially leading to permanent damage.
Moles are abnormal but harmless concentrations of melanin.
What are signs that a mole may be becoming a melanoma?
Signs of possible melanoma are asymmetrical shape, irregular borders, change in color, and diameter larger than a pencil eraser.
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10. Skin Color (cont’d.) Physiological changes: Pathological 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
Jaundice can be a sign of liver disease; the liver is unable to excrete bilirubin, so it is deposited in the skin. In light-skinned people, bronze skin can signal poor adrenal function. A bruise, or ecchymosis, is clotted blood under the skin.
Fear can make a person look white as a sheet. Physiologically, what is going on?
Vasoconstriction is part of the fear response.
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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
What role do the arrector pili muscles play?
When the arrector pili muscles contract, they cause the hair to stand up on end.
The hair follicle is surrounded by epidermal tissue.
Distinguish between hirsuitism and alopecia.
The former can be caused by steroid therapy and the latter can be caused by cancer or chemotherapy.
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
Nails are thin plates of stratified squamous epithelial cells. They contain a very hard form of keratin and slide over a layer called the nail bed, which is part of the epidermis.
Clubbing is an indication chronic lung or heart disease; it results from chronically poor oxygenation of the nail and fingertip.
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
Sudoriferous
Sweat glands
What is the role of the vernix caseosa?
This cream cheese–like covering found on the fetus protects it from maceration.
What happens when the sebaceous glands become blocked?
When accumulated sebum blocks a sebaceous gland and is exposed to air and dries out, it turns black and forms a blackhead. If it becomes infected with staphylococci, it becomes a pustule, or pimple.
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
Eccrine glands: Critical for temperature regulation
Types of modified sweat glands:
Mammary glands: Secrete milk
Ceruminous glands: Secrete ear wax (cerumen)
There are two types of sweat glands, apocrine and eccrine.
Apocrine sweat glands are found in the axillary and genital areas.
These glands develop during puberty. When broken down by bacteria on the skin surface, sweat from these glands cause body odor.
The eccrine glands are active at birth and located throughout the body. Crucial for temperature regulation, eccrine gland sweat cools the body as it evaporates from the skin surface.
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.
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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
What is the “normal” body temperature?
Normal body temperature can range from 97 to 100 F.
What are excessive decrease and increase in body temperature?
Excessive decrease is hypothermia; excessive increase is hyperthermia.
How can core and shell temperature be measured?
Core temperature is measured rectally and shell temperature is measured at the axillary site.
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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
Heat is produced by metabolizing cells.
The amount of heat is affected by food consumption, physical activity, and hormonal secretion (as in thyroid gland disorders).
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18. Heat Loss Sites: Skin (80%), lungs, and excretory products (20%)
Types:
Radiation
Conduction
Convection
Evaporation
Why do most people feel so uncomfortable on a hot and humid day?
Humidity prevents evaporation, so less heat is carried away from the skin.
A cooling blanket to treat hyperthermia is an example of conduction.
An example of convection is the use of a fan to cool the body.
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19. Temperature Regulation
Hypothalamus
Heat lost by:
Dilation of blood vessels
Sweating
Heat conserved by
Shivering
Blood vessel constriction
Less sweat
Pyrogens reset the hypothalamus at a higher temperature. Intense heat can cause heat syncope, heat cramps, heat exhaustion, or heat stroke.
In heat stroke, thermoregulatory mechanisms fail. Core temperature exceeds 104° F, and hallucinations or altered mentation may occur.
With slower metabolisms and thinner skin, older adults are more prone to hypothermia.
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20. 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
Neonates wear hats in the nursery because so much heat loss happens through their large, bald skulls.
Preterm infants have less capacity to thermoregulate, so they are often in incubators.
Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved.

21. Issues in Temperature Regulation
Hyperthermia: Syncope, cramps, heat exhaustion, heat stroke
Hypothermia: Slowed metabolism, fibrillation
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22. Burns: Classified by Depth
Partial thickness burns
First-degree
Second-degree
Full-thickness burn
Third-degree
What type of burn is sunburn?
It is a first-degree burn.
Third-degree burns are pain-free, but the areas of first- and second-degree burns that often surround the more severe burn will still hurt.
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23. Burns: Classified by Extent
“Rule of nines”
Eschar
Acts like a tourniquet
Breeds bacteria
Secretes toxins
What is the extent of a burn on the front and back of an adult’s limbs?
According to the rule of nines, 36% of the body is burned.
Why is eschar removed as part of postburn therapy?
Eschar can act like a tourniquet, cutting off blood supply or preventing chest expansion. It becomes a breeding ground for bacteria and secretes toxins into the blood.
Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved.

24. Skin Care All ages: Especially in older adults:
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.
Both the sun and tanning beds expose people to UV radiation.
In older adults, frequent bathing with soap dries the skin.
Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved.