1. Chapter 06 *Lecture Outline
*See separate Image PowerPoint slides for all figures and tables pre-inserted into PowerPoint without notes.
PowerPoints prepared by Melanie Waite-Altringer
Biology Faculty Member of
Anoka-Ramsey Community College
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2. Chapter 6
Integumentary System

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Introduction
A. Organs are body structures composed of two or more different tissues.
B. The skin and its accessory organs make up the integumentary system.

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Skin and Its Tissues
A. The skin is a large organ responsible for maintaining homeostasis through temperature regulation, protection of underlying tissues, retardation of water loss, housing sensory receptors, synthesizing certain chemicals, and excreting wastes.

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B. The skin consists of an outer epidermis and a dermis, connected to underlying tissue by the subcutaneous layer (hypodermis).

6. Fig06.01a Hair shaft Sweat Sweat gland pore Stratum corneum Epidermis
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Hair shaft
Sweat
Sweat gland pore
Stratum corneum
Epidermis
Stratum basale
Capillary
Dermal papilla
Basement membrane
Dermis
Sebaceous gland
Arrector pili muscle
Sweat gland duct
Hair follicle
Sweat gland
Subcutaneous
layer
Nerve cell process
Adipose tissue
Blood vessels
Muscle
(a)

7. Fig06.01b (b) Epidermis Dermis Hair follicle Arrector pili muscle
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Epidermis
Dermis
Hair follicle
Arrector pili
muscle
Sebaceous
gland
©Image Source/Getty Images
(b)

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C. Epidermis
1. The epidermis is made up of stratified squamous epithelium and lacks blood vessels.
2. The layer of reproducing cells (the stratum basale), which lies at the base of the epidermis, is well- nourished by dermal blood vessels.

9. Fig06.02 Stratum corneum Stratum lucidum Stratum granulosum
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Stratum corneum
Stratum lucidum
Stratum granulosum
Stratum spinosum
Stratum basale
Basement
membrane
Dermal papilla
Dermis
(a)
(b)
©The McGraw-Hill Companies, Inc./Al Telser, photographer

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3. Cells are pushed outward as new cells are formed, and become keratinized as they die. Four or five layers may be seen: stratum basale, stratum spinosum, stratum granulosum, and stratum corneum are always present and the stratum lucidum is found in the thicker palms and soles.

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The epidermis is important because it protects against water loss, mechanical injury, chemicals, and microorganisms.
Melanocytes, which lie deep in the epidermis and underlying dermis, produce a pigment called melanin that protects deeper cells from the sun's ultraviolet rays.
6. Melanocytes pass melanin to nearby cells through cytocrine secretion.

12. Fig06.03b Cellular extension of melanocyte Epidermis Pigment granules
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Cellular
extension
of melanocyte
Epidermis
Pigment
granules
Golgi
apparatus
Melanocyte
nucleus
Basement
membrane
Dermis
(b)

13. 4. Circulation within dermal blood vessels affects skin color.
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D. Skin Color
1. Skin color results from a combination of genetic, environmental, and physiological factors.
2. Genetic differences in skin color result from differing amounts of melanin and in the size of melanin granules.
3. Exposure to sunlight causes darkening of skin as melanin production increases.
4. Circulation within dermal blood vessels affects skin color.

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E. Dermis
1. The dermis binds the epidermis to underlying tissues. Epidermal ridges and dermal papillae cause the border to be uneven.
2. The dermis consists of connective tissue with collagen and elastic fibers within a gel-like ground substance.

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3. Dermal blood vessels carry nutrients to upper layers of skin and help to regulate temperature.
4. The dermis also contains nerve fibers, sensory fibers, hair follicles, sebaceous glands, and sweat glands.

16. Accessory Structures of the Skin
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Accessory Structures of the Skin
A. Nails
1. Nails are protective coverings over the ends of fingers and toes.
2. Nails consist of a nail plate and stratified squamous epithelial cells overlying the nail bed, with the lunula as the most actively growing region of the nail root.
3. As new cells are produced, older ones are pushed outward and become keratinized.

17. Lunula Nail bed Nail plate Fig06.04
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Lunula
Nail bed
Nail plate

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B. Hair Follicles
1. Hair can be found in nearly all regions of the skin except palms, soles, lips, nipples, and portions of external genitalia.
2. Each hair develops from cells at the base of a tubelike depression called the hair follicle. The dermis
contain the hair root.
3. As new cells are formed, old cells are pushed outward and become keratinized, and die forming the hair shaft.

19. Fig06.05a Hair shaft Pore Basement membrane Sebaceous gland
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Hair shaft
Pore
Basement
membrane
Sebaceous
gland
Arrector pili
muscle
Hair root
(keratinized
cells)
Hair follicle
Eccrine
sweat gland
Region of
cell division
Dermal
blood
vessels
(a)

20. Fig06.05b Hair follicle Hair root Adipose tissue Region of cell
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Hair
follicle
Hair root
Adipose
tissue
Region of cell
division
©The McGraw-Hill Companies, Inc./Al Telser, photographer
(b)

21. 6. The arrector pili muscle attaches to each hair follicle.
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4. A bundle of smooth muscle cells, called the arrector pili muscle, attaches to each hair follicle. These muscles cause goose bumps when cold or frightened.
5. Hair color is determined by genetics; melanin from melanocytes is responsible for most hair colors. Dark hair has eumelanin while blonde and red hair have pheomelanin.
6. The arrector pili muscle attaches to each hair follicle.

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C. Sebaceous glands
1. Sebaceous glands (holocrine glands) are associated with hair follicles and secrete sebum that waterproofs and moisturizes the hair shafts.

23. Fig06.07 Hair follicle Sebaceous gland
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Hair follicle
Sebaceous gland
©The McGraw-Hill Companies, Inc./Al Telser, photographer

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D. Sweat Glands
1. Sweat glands (sudoriferous glands) are either eccrine, which respond to body temperature, or apocrine, which respond to body temperature, stress, and sexual arousal. The secretions exit via a surface pore.
2. Modified sweat glands, called ceruminous glands, secrete wax in the ear canal.
3. Mammary glands, another modified type of sweat glands, secrete milk.

25. Regulation of Body Temperature
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Regulation of Body Temperature
A. Proper temperature regulation is vital to maintaining metabolic reactions.
B. The skin plays a major role in temperature regulation with the hypothalamus controlling it.
C. Active cells, such as those of the heart and skeletal muscle, produce heat.

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D. Heat may be lost to the surroundings from the skin through radiation.
E. The body responds to excessive heat by dilation of dermal blood vessels and sweating.
F. The body responds to excessive cooling by constricting dermal blood vessels, inactivating sweat glands, and shivering.

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Healing of Wounds
A. Inflammation, in which blood vessels dilate and become more permeable, causing tissues to become red and swollen, is the body's normal response to injury.
B. Superficial cuts are filled in by reproducing epithelial cells.

28. C. The blood clot and dried tissue fluids form a scab.
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C. The blood clot and dried tissue fluids form a scab.
D. If the wound is deep, extensive production of collagenous fibers may form an elevation above the normal epidermal surface forming a scar.
E. Large wounds leave scars and healing may be accompanied by the formation of granulations.