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PowerPoint® Lecture Slides prepared by Vince Austin, Bluegrass Technical and Community College CHAPTER Elaine N. Marieb Katja Hoehn Human Anatomy & Physiology SEVENTH EDITION Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings 5 The Integumentary System Components of the Integumentary System Skin Hair Nails Glands Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Skin (Integument) A large organ composed of all 4 tissue types 22 square feet 1-2mm thick ~10lbs. Consists of three major regions Epidermis – outermost superficial region – only epithelial tissue Dermis – middle region – has connective, nervous and muscular tissue Hypodermis (superficial fascia or Subcutaneous Layer) – deepest region – Adipose and Areolar Tissue Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Hair shaft Pore Dermal papillae (papillary layer of dermis) Epidermis Meissner's corpuscle Free nerve ending Reticular layer of dermis Sebaceous (oil) gland Arrector pili muscle Dermis Sensory nerve fiber Eccrine sweat gland Pacinian corpuscle Artery Hypodermis (superficial fascia) Hair root Hair follicle Eccrine sweat Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings gland Vein Adipose tissue Hair follicle receptor (root hair plexus) Figure 5.1 Epidermis Composed of keratinized stratified squamous epithelium, consisting of four distinct cell types and four or five layers Cell types include keratinocytes, melanocytes, Merkel cells, and Langerhans’ cells Outer portion of the skin is exposed to the external environment and functions in protection Stratified Squamous Epithelium Avascular 5 Distinct Layers Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Cells of the Epidermis Keratinocytes – 90%, Make keratin Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Melanocytes – 8% -produce the brown pigment melanin Langerhans’ cells – epidermal macrophages that help activate the immune system Merkel cells – function as touch receptors in association with sensory nerve endings Layers of the Epidermis Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 5.2b Layers of the Epidermis: Stratum Basale (Basal Layer) Deepest epidermal layer firmly attached to the dermis Consists of a single row of the youngest keratinocytes – Stratum Germinativum Contains Keratinocytes, Merkel Cells, Melanocytes and Stem Cells Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Layers of the Epidermis: Stratum Spinosum (Prickly Layer) 8-10 Layers of cells Cells contain a weblike system of intermediate filaments attached to desmosomes Melanin granules and Langerhans’ cells are abundant in this layer Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Layers of the Epidermis: Stratum Granulosum (Granular Layer) Thin; three to five cell layers of flat dying cells Show nuclear degeneration Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Layers of the Epidermis: Stratum Lucidum (Clear Layer) Thin, transparent band superficial to the stratum granulosum Consists of a 3-5 rows of flat, dead keratinocytes Present only in thick skin Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Layers of the Epidermis: Stratum Corneum (Horny Layer) Outermost layer of keratinized cells (25-30 layers) – surrounded by lipids Continuously shed Accounts for three quarters of the epidermal thickness Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Keratinization and Epidermal Growth ~4 week journey for keratinocytes from the bottom to the top of the skin Psoriasis – chronic skin disorder Cells shed in 7-10 days as flaky silvery scales Abnormal keratin produced Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Skin Grafts If stratum basale layer and its stem cells are destroyed, new skin CANNOT regenerate Skin Graft – covering of a wound with a piece of healthy skin Autograft – from self Isograft – from twin Autologous Skin – transplant of a patient’s skin that was grown in a culture Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Layers of the Epidermis Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 5.2b Dermis Second major skin region containing strong, flexible connective tissue Collagen and elastic fibers, fibroblasts, macrophages and adipocytes Composed of two layers – papillary and reticular Contains hair follicles, glands, nerves and blood vessels Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Layers of the Dermis: Papillary Layer Papillary layer Areolar connective tissue with collagen and elastic fibers Its superior surface contains peglike projections called dermal papillae Dermal papillae contain capillary loops, Meissner’s corpuscles, and free nerve endings Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Layers of the Dermis: Reticular Layer Reticular layer Accounts for approximately 80% of the thickness of the skin Collagen fibers in this layer add strength and resiliency to the skin Elastin fibers provide stretch-recoil properties Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Hypodermis Subcutaneous layer deep to the skin Composed of adipose and areolar connective tissue Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Skin Color Three pigments contribute to skin color Melanin – yellow to reddish-brown to black pigment, responsible for dark skin colors Freckles and pigmented moles – result from local accumulations of melanin Made by melanocytes Same number of melanocytes in everyone UV rays in sunlight increase melanin Albinism – in alack of tyrosinase, so the body can’t covert tyrosine into melanin = no pigment Vitiligo – autoimmune loss of melanocytes in areas of the skin which produces white patches Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Skin Color Carotene – yellow to orange pigment, most obvious in the palms and soles of the feet Found in Stratum Corneum and Dermis Hemoglobin – reddish pigment responsible for the pinkish hue of the skin Carries oxygen in the blood If other pigments are not present, the epidermis is translucent so pinkness will be evident Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Skin Color as a Diagnostic Clue Jaundice Yellowish color to skin and whites of eyes Build-up of yellow bilirubin in the blood from the liver not breaking it down properly Cyanotic Bluish color to nail beds and skin Hemoglobin is depleted of oxygen – looks purple/blue Erythema Redness of skin due to the enlargement of capillaries in the dermis Present during inflammation, infection, allergy or burns Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Glands of the Skin Specialized Exocrine Glands found in the Dermis Sebaceous (Oil) Glands Sudiferous or Sudoriferous (Sweat) Glands Mammary Glands (Milk) Ceruminous (Wax) Glands Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Sebaceous Glands Simple alveolar glands found all over the body Soften skin when stimulated by hormones Secrete an oily secretion called sebum Most open into hair shafts Sebum… Keeps hair and skin soft and pliable Inhibits growth of bacteria and fungi Acne Bacterial inflammation of glands Secretions stimulated by hormones at puberty Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Sweat Glands Secrete products through ducts Regulate body temperature through perspiration Eccrine sweat glands – found in palms, soles of the feet, and forehead Apocrine sweat glands – found in axillary and pubic areas – secretory portion in dermis with duct that opens onto hair follicle Mammary glands – specialized sweat glands that secrete milk Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Ceruminous Glands Modified sweat glands that produce a waxy secretion in the ear canal Cerumen contains secretions of oil and wax glands Helps form a barrier to the inner ear – prevents foreign bodies from getting in Impacted cerumen may impact hearing Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Hair Strands of dead keratinized cells produced by hair follicles Contains hard keratin which is tougher and more durable than soft keratin of the skin Made up of the shaft projecting from the skin, and the root embedded in the skin Consists of a core called the medulla, a cortex, and an outermost cuticle Pigmented by melanocytes at the base of the hair Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Hair Function and Distribution Functions of hair include: Helping to maintain warmth Alerting the body to presence of insects on skin Guarding the scalp against physical trauma, heat loss, and sunlight Eyelashes protect eyes Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Hair Function and Distribution Hair is distributed over the entire skin surface except: Palms, soles, and lips Nipples and portions of the external genitalia Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Hair Structures Arrector Pili Hair Root Plexus Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Smooth muscle in dermis that contracts with cold or fear Detects hair movement Types of Hair Vellus – pale, fine body hair found in children and the adult female Terminal – coarse, long hair of eyebrows, scalp, axillary, and pubic regions Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Hair Thinning and Baldness Alopecia – hair thinning in both sexes True, or frank, baldness Genetically determined and sex-influenced condition Male pattern baldness – caused by follicular response to DHT Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Hair Color Result of melanin in the hair bulb – made by melanocytes Dark hair contains true melanin Blond hair contains melanin and sulfur Red hair contains melanin and iron Gray hair is a result of a decline in melanin production White hair is a result of air bubbles in the hair shaft Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Structure of a Nail Scalelike modification of the epidermis on the distal, dorsal surface of fingers and toes Tightly packet keratinized cells. 3 parts Nail Body (visible portion, pink b/c of capillaries, free edge is white) Nail Root (buried under skin layers, lanula is white due to a thick Stratum Basale Eponychium (cuticle) – stratum corneum layer Nails grow about 1mm per week Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 5.6 Nail Picture Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Functions of the Integumentary System Protection – chemical, physical, and mechanical barrier Body temperature regulation is accomplished by: Dilation (cooling) and constriction (warming) of dermal vessels Increasing sweat gland secretions to cool the body Cutaneous sensation – exoreceptors sense touch and pain Excretion and Absorption Synthesis of Vitamin D Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Synthesis of Vitamin D Sunlight activates a precursor to Vitamin D Enzymes in the liver and kidneys transform that molecule into Calcitrol – most active form of Vitamin D Calcitrol is necessary in the absorption of Ca from food in the gastrointestinal tract. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Types of Skin Thin Skin Covers most of the body Thin epidermis – no Stratum Lucidum No epidermal ridges, less sweat glands and sensory receptors Thick Skin Only on palms and soles Thick epidermis – distinct Stratum Lucidum and thick Stratum Corneum Lacks hair follicles and sebaceous glands Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Photodamage UVA and UVB rays both damage the skin Acute overexposure causes sunburn DNA damage in epidermal cells can lead to skin cancer UVA produces oxygen free radicals that damage collagen and elastic fibers and lead to wrinkling of the skin Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Skin Cancer Most skin tumors are benign and do not metastasize A crucial risk factor for nonmelanoma skin cancers is the disabling of the p53 gene Newly developed skin lotions can fix damaged DNA ~1 million cases diagnosed per year Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Skin Cancer The three major types of skin cancer are: Basal cell carcinoma – rarely metastisize Squamous cell carcinoma – may metastisize Malignant melanomas – metastisize quickly Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Basal Cell Carcinoma Least malignant and most common skin cancer Stratum basale cells proliferate and invade the dermis and hypodermis Slow growing and do not often metastasize Can be cured by surgical excision in 99% of the cases Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Squamous Cell Carcinoma Arises from keratinocytes of stratum spinosum Arise most often on scalp, ears, and lower lip Grows rapidly and metastasizes if not removed Prognosis is good if treated by radiation therapy or removed surgically Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Melanoma Cancer of melanocytes is the most dangerous type of skin cancer because it is: Highly metastatic Resistant to chemotherapy Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Skin Cancers Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 5.7a–c Melanoma Melanomas have the following characteristics (ABCD rule) A: Asymmetry; the two sides of the pigmented area do not match B: Border is irregular and exhibits indentations C: Color (pigmented area) is black, brown, tan, and sometimes red or blue D: Diameter is larger than 6 mm (size of a pencil eraser) Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Melanoma Treated by wide surgical excision accompanied by immunotherapy Chance of survival is poor if the lesion is over 4 mm thick Resistant to Chemotherapy Risk factors – skin color, sun exposure, family history, age and immunological status Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Burns Destruction of proteins of the skin Chemicals, electricity, heat Problems Shock due to water, plasma and plasma protein loss Circulatory and kidney problems from loss of plasma Bacterial Infection Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Types of Burns - 3 First-degree Second Degree Third Degree Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings 1st Degree Burns Only effect the epidermis Simple sunburn Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Burns Second-degree – destroys the entire epidermis and part of the dermis Fluid-filled blisters separate the epidermis and dermis Epidermal derivatives are not damaged Heals without grafting in 3-4 weeks, may cause scarring Symptoms mimic first degree burns, but blisters also appear Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Burns Third-degree – entire thickness of the skin is damaged Epidermis, Dermis and Epidermal Derivatives are damaged Burned area appears gray-white, cherry red, or black; there is no initial edema or pain (since nerve endings are destroyed) Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Rule of Nines Estimates the severity of burns Burns considered critical if: Over 25% of the body has second-degree burns Over 10% of the body has third-degree burns There are third-degree burns on face, hands, or feet Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Rule of Nines Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 5.8a Developmental Aspects of the Integument: Fetal Epidermis develops from ectoderm Dermis and hypodermis develop from mesoderm Lanugo – downy coat of delicate hairs covering the fetus Vernix caseosa – substance produced by sebaceous glands that protects the skin of the fetus in the amnion Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Developmental Aspects of the Integument: Adolescent to Adult Skin and hair become oilier and acne may appear Skin shows the effects of cumulative environmental assaults around age 30 Scaling and dermatitis become more common Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Developmental Aspects of the Integument: Old Age Epidermal replacement of cells slows and skin becomes thinner Skin becomes dry and itchy Subcutaneous fat layer diminishes, leading to intolerance of cold Decreased elasticity and loss of subcutaneous tissue leads to wrinkles Decreased numbers of melanocytes and Langerhans’ cells increase the risk of skin cancer Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings