20 The Integumentary System
Learning Outcomes 20.1 List the functions of skin. 20.2 Explain the role of skin in regulating body temperature. 20.3 Describe the layers of skin and the characteristics of each layer. 20.4 Explain the factors that affect skin color. 20.5 Identify and describe common skin lesions.
Learning Outcomes(cont.) 20.6 List the accessory organs of skin and describe their structures and functions. 20.7 Explain the process of skin healing, including scar production. 20.8 Describe the effects of aging on skin. 20.9 List the different types of burns and describe their appearances and treatments.
Learning Outcomes(cont.) 20.10 Describe the causes, signs and symptoms, and treatments of various types of skin cancer. 20.11 Describe the causes, signs and symptoms, and treatments of common skin disorders. 20.12 Explain the ABCDE rule and its use in evaluating melanoma. 20.13 Using the acronym CAUTION, list the seven warning signs of cancer.
Integumentary system consists of skin and its accessory organs Accessory organs: Hair follicles Nails Skin glands Introduction Skin is the body’s outer covering and its largest organ.
Functions of the Integumentary System • Protection • First line of defense against • Bacteria • Viruses • Protects underlying structures from • Ultraviolet (UV) radiation • Dehydration
Functions of the Integumentary System(cont.) • Body temperature regulation • If too hot • Dermal blood vessels dilate • Vessels carry more blood to surface so heat can escape • If too cold • Dermal blood vessels constrict • Prevents heat from escaping
Functions of the Integumentary System(cont.) • Vitamin D production • Needed for calcium absorption • Sensation • Sensory receptors • Excretion • Small amounts of waste products are lost through perspiration
Super! Apply Your Knowledge What are the functions of the integumentary system? ANSWER: The functions of the integumentary system are protection, regulation of body temperature, vitamin D production, sensation, and excretion.
Epidermis • Most superficial layer • Two parts • Stratum corneum • Outermost layer • Mostly dead cells form an impermeable layer • Stratum basale(stratum germinativum) • Deepest layer • Cells constantly dividing and pushing older cells outward To Figure of Skin
Epidermis (cont.) • Keratinocyte– most common • Makes and accumulates keratin • Durable protein that makes the epidermis waterproof and resistant to pathogens • Melanocyte • Makes the pigment melanin • Traps UV radiation and prevents damage to underlying layers of the skin
Dermis • Deeper of the two skin layers • Contains all major tissue types, plus • Sudoriferous (sweat) glands • Sebaceous (oil) glands • Hair follicles and arrector pili muscles • Collagen, elastin, and nerve fibers • Blood vessels • Binds the epidermis to the subcutaneous tissue To Figure of Skin
Subcutaneous Layer • Hypodermis • Composed of • Adipose (fat) and loose connective tissue • Blood vessels and nerves • Functions • Storage in adipose tissue • Cushions and insulates underlying structures To Figure of Skin
Apply Your Knowledge Where are melanocytes and keratinocytes, and what is their function? ANSWER: Both are located in the epidermis of the skin. Keratinocytes make and accumulate keratin, which is a durable protein that makes the epidermis waterproof and resistant to pathogens. Melanocytes make the pigment melanin, which traps UV radiation and prevents damage to underlying layers of the skin. Excellent!
Skin Color • Determined by amount of melanin in the epidermis of skin • The more melanin, the darker the skin color • Range is from yellowish to brownish
Skin Color (cont.) • Oxygenated blood • Amount of oxygen dissolved in the hemoglobinof the red blood cells • Hemoglobin – a pigment in the RBCs • If blood is well-oxygenated, skin will be pink • If oxygen level in blood is low, skin will be pale or have a bluish color (cyanosis)
Nice Job! Apply Your Knowledge What affects skin color? ANSWER: The amount of melanin produced by the melanocytes and the oxygenation of the blood.
Skin Lesions • Any variation in the skin • As simple as a freckle • As serious as a tumor
Apply Your Knowledge Match the following: ___ Keloid A. A blister ___ Vesicle B. A crack in the skin’s surface ___ Crust C. An overgrowth of scar tissue ___ Fissure D. A small, flat scaly area of skin ___ Ulcer E. Dried blood or pus on the skin ___ Plaque F. A wound that results from tissue loss ANSWER: C BRAVO! A E B F D
Hair follicles Tube-like depressions in the dermis of skin Generate hairs Alopecia (baldness) occurs when follicles die Arrector pili muscles attached to follicles cause goose bumps Sebaceous glands Produce sebumto keep hair soft Prevent bacteria from growing on skin Nails Protect the ends of fingers and toes Hard keratin Accessory Organs Diagram
Sudoriferous (sweat) glands Located in the dermis of skin Types Eccrine gland Produce watery type of sweat Activated by heat Apocrine gland Produce thicker type of sweat with more proteins Concentrated in armpit and groin areas Activated by nervousness or stress Accessory Organs (cont.) Diagram
Skin Healing • Injury inflammation • Redness due to dilation of nearby blood vessels • Swelling because vessels leak fluid into spaces between cells • Pain because excess fluid activates pain receptors
Scab replaces blood clot Clotted blood and other dried tissue Collagen fibers replace scab Bind the edges of wound; major component of scars Skin Healing (cont.) • Inflammation promotes healing • Extra blood to area • Extra nutrients for skin repair • Defensive cells Injury occurs Blood clot forms
Apply Your Knowledge How does inflammation promote healing of the skin? ANSWER: Inflammation promotes healing by bringing extra blood, nutrients for skin repair, and defensive cells to the area of injury. Correct
Skin and Aging • Skin loses firmness due to • Loss of elastin and collagen fibers in dermis • Loss and shifting of underlying adipose tissues • Skin color changes • Dermis becomes thinner and more transparent • Paler due to decrease in circulation
Skin and Aging (cont.) • Melanocytes decrease • Those remaining gather “age” spots • Hair grays and becomes thinner • Decreased tolerance to temperature changes • Sudoriferous glands decrease in number • Decreased perspiration, hard to adjust to high temperatures • Loss in adipose tissue and decreased circulation • Increased sensitivity to cold
Apply Your Knowledge What happens to the skin in the elderly? ANSWER: As a person ages, the skin loses firmness, skin color changes, melanocytes decrease, and tolerance to temperature changes decreases due to a loss of adipose tissue and sweat glands. Very Good!
Burns • Second leading cause of accidental death in the U.S. • Rule of nines is used to determine extent (coverage) of burn • Extent of body surface area • 11 body areas Rule of Nines
Superficial – first-degree • Epidermis only • Pain, redness, swelling • Partial-thickness – second-degree • Epidermis and dermis • Pain, redness, swelling, blisters • Full-thickness – third-degree • All layers of skin and often underlying structures • Skin appears charred • Always requires medical attention Burn Severity Burns
Burns: Treatment • Do not remove anything sticking to the burn • Do not apply butter, lotions, or ointments • Cool with large amounts of water • Cover with sterile sheet or plastic bag
Using Figure 24-5, determine burn extent for a patient who has burnt his anterior face and both arms. Apply Your Knowledge Click for Figure 24-5 Rule of Nines ANSWER: Head = 9% Both arms, hands, and shoulders = 18% + 18% 9% + 18% + 18% = 45% It all adds up to a right answer!
Skin Cancer • Basal cell carcinoma – progresses slowly and rarely spreads to other body parts • Squamous cell carcinoma – more likely to spread to surrounding tissues • Malignant melanoma – more aggressive and occurs anywhere • Most arise from melanocytes
Signs and symptoms New growth or sore that will not heal Waxy, smooth, red, pale, flat, or lumpy May or may not bleed Treatment: Curettage and electrodessication Cryosurgery Mohs’ surgery Laser therapy Basal Cell Carcinoma
20-42 Squamous Cell Carcinoma • Less common than basal cell carcinoma • Found on face, lips, ears, and backs of hands • Signs and symptoms and treatments are the same as for basal cell carcinoma
Signs and Symptoms From melanocytes Appear on trunk, head, neck of men Appear on arms and legs of women Itches or bleeds Treatment Surgery and biopsy Removal of lymph nodes Chemotherapy and radiation therapy Immunotherapy Malignant Melanoma
24-46 Cancer Warning Signs C – Change in bowel or bladder habits A – A sore that will not heal U – Unusual bleeding or discharge T – Thickening or lump I– Indigestion or difficulty swallowing O – Obvious change in wart or mole N – Nagging cough or hoarseness
Apply Your Knowledge True or False: ___ Basal cell carcinoma is the most aggressive form of skin cancer and can form anywhere. ___ Squamous cell carcinoma is more likely to spread to surrounding tissues. ___ Lesions of melanoma appear on trunk, head, neck of men and on arms and legs of women. ___ The borders of skin cancers are usually regular. ___ Basal cell carcinoma progresses slowly and rarely spreads to other body parts. ANSWER: F Melanomas are more aggressive. T T F Borders are irregular. T Good Job!
Alopecia Results in hair loss Cellulitis Inflammation of connective tissue in skin Common Skin Disorders • Dermatitis • Inflammation of skin or a rash • Eczema • Chronic dermatitis • Folliculitis • Inflammation of hair follicles
Herpes simplex Type 1 – cold sores Type 2 – genital Herpes zoster Shingles Impetigo Oozing skin lesions that eventually crust over Pediculosis Head lice Body lice Pubic lice Psoriasis Inherited autoimmune disorder Common Skin Disorders(cont.)
Ringworm Tinea corporis Tinea capitis Tinea pedis Rosacea Dilation of small facial blood vessels Scabies Contagious skin condition caused by mites Warts Harmless growths caused by a virus Common Skin Disorders(cont.)
Apply Your Knowledge ANSWER: C Match the following: ___ Alopecia A. Dilation of small facial blood vessels ___ Folliculitis B. Inherited autoimmune disorder ___ Impetigo C. Hair loss ___ Psoriasis D. Growths caused by a virus ___ Rosacea E. Inflammation of hair follicles ___ Warts F. Oozing skin lesions E F B A D Right!
In Summary 20.1 The functions of skin include protection, body temperature regulation, vitamin D production, sensation, and excretion. 20.2 When the body is warm, the dermal blood vessels dilate, allowing heat to escape and cool the body. When the body is cool, the same vessels constrict, preventing the heat carried by blood from escaping, keeping the body warmer. 20.3 The topmost layer of the skin is the epidermis. The dermis is the complex middle layer. The innermost layer, attaching the skin to muscle, is the subcutaneous layer.