CHAPTER 4 Integumentary system.pdf

PowerPoint® Lecture Slides Prepared by Patty Bostwick-Taylor, Florence-Darlington Technical College C H A P T ER 4 Skin and...

PowerPoint® Lecture Slides Prepared by Patty Bostwick-Taylor, Florence-Darlington Technical College C H A P T ER 4 Skin and Body Membranes © 2012 Pearson Education, Inc.  Skin (cutaneous membrane) Skin derivatives Sweat glands Oil glands Integumentary Hair System Nails © 2012 Pearson Education, Inc.  Hair shaft Dermal papillae Epidermis Papillary Pore layer Appendages of skin Eccrine sweat gland Arrector pili muscle Dermis Sebaceous (oil) gland Reticular layer Hair follicle Hair root Hypodermis (superficial fascia) Cutaneous vascular plexus Nervous structures Sensory nerve fiber Lamellar corpuscle Adipose tissue Hair follicle receptor (root hair plexus) © 2012 Pearson Education, Inc. Figure 4.3  2 Regions of the Skin Epidermis outer layer Stratified squamous epithelium Cornified or keratinized (hardened by keratin) to prevent water loss Avascular Most cells are keratinocytes Dermis Dense connective tissue Vascular © 2012 Pearson Education, Inc.  Skin Structure Subcutaneous tissue (hypodermis) is deep to dermis Not technically part of the skin Anchors skin to underlying organs Composed mostly of adipose tissue © 2012 Pearson Education, Inc.  Layers of the Epidermis Stratum basale (stratum germinativum) Deepest layer of epidermis Lies next to dermis Wavy borderline with the dermis anchors the two together Cells undergoing mitosis Daughter cells are pushed upward to become the more superficial layers © 2012 Pearson Education, Inc.  Layers of the Epidermis Stratum spinosum (Pricky layer) Several cell layers thick Contain weblike system of intermediate filaments Stratum granulosum (Granular layer) Four to six layers thick Accumulates 2 types of granules: Keratohyaline granules – help to form keratin in the upper layer Lamellar granules – contain water resistant glycolipid for slowing water loss across the epidermis © 2012 Pearson Education, Inc.  Layers of the Epidermis Stratum lucidum (Clear layer) Formed from dead cells of the deeper strata Occurs only in thick, hairless skin of the palms of hands and soles of feet Stratum corneum (Horny layer) Outermos t layer of epidermis Shingle-like dead cells are filled with keratin (protective protein prevents water loss from skin) © 2012 Pearson Education, Inc.  Layers of the Epidermis Summary of layers from deepest to most superficial Stratum basale Stratum spinosum Stratum granulosum Stratum lucidum (thick, hairless skin only) Stratum corneum © 2012 Pearson Education, Inc.  Cells in the Epidermis Keratinocytes Produce keratin, fibrous protein that helps give the epidemis its protective properties Arise in the deepest part of the epidermis, stratum basale © 2012 Pearson Education, Inc.  Cells in the Epidermis Melanocytes Spider-shaped epithelial cells Synthesize melanin pigment Found in the deepest part of the epidermis © 2012 Pearson Education, Inc.  Cells in the Epidermis Dendritic (Langerhans) Cells Arise from bone marrow and migrate to the epidermis Ingest foreign substances Key activators of our immune system Tactile (Merkel) Cells Present at the epidermal- dermal junction Functions as sensory receptor for touch © 2012 Pearson Education, Inc.  Two layers Papillary layer (upper dermal region) Areolar connective tissue Collagen and elastic fibers form a loosely woven mat Projections called dermal papillae Some contain capillary loops Others house pain receptors and touch receptors called tactile or Meissner’s Dermis corpuscles © 2012 Pearson Education, Inc.  Dermis Two layers Reticular layer 80% of the thickness of the dermis Dense fibrous connective tissue Cleavage (tension lines) – important to surgeon Flexure lines – dermal folds that occur at or © 2012 Pearson Education, Inc.  Normal Skin Color Determinants Melanin Polymer made of tyrosine amino acids Yellow, brown, or black pigments Carotene Orange-yellow pigment from some vegetables Accumulates in the stratum corneum and in fatty tissue of the hypodermis Hemoglobin Red coloring from blood cells in dermal capillaries Oxygen content determines the extent of red coloring © 2012 Pearson Education, Inc.  Alterations in Skin Color Redness (erythema)—due to embarrassment, inflammation, hypertension, fever, or allergy Pallor (blanching)—due to emotional stress such as fear, anemia, low blood pressure, impaired blood flow to an area Jaundice (yellowing)—liver disorder Bronzing – Addison’s disease Bruises—hematomas © 2012 Pearson Education, Inc.  Skin Appendages Cutaneous glands are all exocrine glands Sebaceous glands Sweat glands Hair Hair follicles Nails © 2012 Pearson Education, Inc.  Appendages of the Skin Oil (sebaceous) glands Produce oil (sebum), accumulated lipids and cell fragments Lubricant for skin Prevents brittle hair Kills bacteria Most have ducts that empty into hair follicles; others open directly onto skin surface Glands are activated at puberty © 2012 Pearson Education, Inc.  Whitehead – accumulated sebum blocks a sebaceous gland duct Blackhead – material oxidizes and dries Acne – an active inflammation of sebaceous glands accompanied by ―pimples” – caused by bacterial infection (Staphylococcus) Seborrhea – overactive sebaceous gland, in infants it is known as ―cradle cap‖ © 2012 Pearson Education, Inc.  Sweat pore Sebaceous Eccrine gland gland Dermal connective tissue Sebaceous gland duct Hair in hair follicle Secretory cells (a) Photomicrograph of a sectioned sebaceous gland (14×) © 2012 Pearson Education, Inc. Figure 4.7a  Appendages of the Skin Sweat (sudoriferous) glands Produce sweat Widely distributed in skin except nipples and parts of external genitalia 2 Types: Eccrine Apocrine © 2012 Pearson Education, Inc.  Two types of sudoriferous glands Eccrine (Merocrine) sweat glands Numerous and abundant in the palms, soles of the feet and forehead Open via duct to pore on skin surface Produce sweat (clear) Apocrine sweat glands Aprox. 2,000 are largely confined to the axillary and anogenital areas Ducts empty into hair follicles Begin to function at puberty Release sweat that also contains fatty acids and proteins (milky/yellowish color) © 2012 Pearson Education, Inc.  Two types of sudoriferous glands Apocrine sweat glands Ceruminous glands Modified apocrine glands found in the lining of the external ear canal Secretion mixes with sebum to produce cerumen or ear wax. Mammary glands Secretes milk © 2012 Pearson Education, Inc.  Sweat pore Sebaceous Eccrine gland gland Dermal connective tissue Eccrine gland duct Secretory cells (b) Photomicrograph of a sectioned eccrine gland (180×) © 2012 Pearson Education, Inc. Figure 4.7b  Sweat and Its Function Composition Mostly water Salts and vitamin C Some metabolic waste Fatty acids and proteins (apocrine only) Function Helps dissipate excess heat Excretes waste products Acidic nature inhibits bacteria growth Odor is from associated bacteria © 2012 Pearson Education, Inc.  Appendages of the Skin Hair or pili Produced by hair follicle Consists of hard keratinized epithelial cells Melanocytes provide pigment for hair color Hair grows in the matrix of the hair bulb in stratum basale © 2012 Pearson Education, Inc. © 2012 Pearson Education, Inc. Figure 4.8c Appendages of the Skin Hair anatomy Central medulla Consist of large cell and air spaces Only part of the hair that contains soft keratin, absent in fine hairs Cortex surrounds medulla Cuticle on outside of cortex Most heavily keratinized Provides strength and helps keep the inner layers tightly compacted  Appendages of the Skin Associated hair structures Hair follicle Dermal and epidermal sheath surround hair root Hair papilla Nipple-like bit of derma tissue, protrudes into the hair bulb Contains knot of capilla that supplies nutrients the growing hair and signals to grow. © 2012 Pearson Education, Inc.  Appendages of the Skin Associated hair structures Hair follicle Dermal and epidermal sheath surround hair root Arrector pili muscle Smooth muscle cells Pulls hairs upright when cold or frightened Important role: contractions force sebum out of hair follicles to the skin surface where it acts as skin lubricant. © 2012 Pearson Education, Inc.  Types of Hair Growth Vellus hair Terminal hair Hirsutism – excessive hairiness – may result from an adrenal gland or ovarian tumor Alopecia – hair thinning and some degree of baldness True or frank baldness Most common, male pattern baldness © 2012 Pearson Education, Inc. Appendages of the Skin Nails Scale-like modifications of the epidermis Heavily keratinized Stratum basale extends beneath the nail bed Responsible for growth Lack of pigment makes them colorless © 2012 Pearson Education, Inc.  Appendages of the Skin Nail structures Free edge Body is the visible attached portion Root of nail embedded in skin Cuticle is the proximal nail fold that projects onto the nail body © 2012 Pearson Education, Inc.  Skin Functions Protection Chemical barriers - include skin secretions and melanin - dermcidin in sweat and bactericidal in sebum kills bacteria outright - secrete natural antibiotics, defensins - wounded skin releases cathelicidins, protective peptides Physical barriers - stratum corneum which is compared to bricks and mortar © 2012 Pearson Education, Inc.  Skin Functions Protection Biological barriers - include dendritic cells of the epidermis, macrophages in the dermis and DNA Body temperature regulation - body works best when temperature remains within homeostatic limits insensible respiration sensible respiration - external environment is cold, dermal blood vessels constrict © 2012 Pearson Education, Inc.  Skin Functions Cutaneous sensation - richly supplied with cutaneous sensory receptors, classified as exteroceptors Ex: tactile (Meissner’s) corpuscles lamellar (Pacinian) corpuscles Metabolic functions - skin is a chemical factory fueled in part by the sun’s rays © 2012 Pearson Education, Inc.  Skin Functions Blood reservoir - dermal vascular supply is extensive and can hold about 5% of body’s entire blood volume. Excretion - eliminates limited amounts of nitrogen- containing waste (ammonia, urea and uric acid) in sweat © 2012 Pearson Education, Inc.  Skin Homeostatic Imbalances Burns Tissue damage and cell death caused by heat, electricity, UV radiation, or chemicals Associated dangers Dehydration Electrolyte imbalance Circulatory shock © 2012 Pearson Education, Inc.  Rule of Nines Way to determine the extent of burns Body is divided into 11 areas for quick estimation Each area represents about 9 percent of total body surface area © 2012 Pearson Education, Inc.  Totals 41/2% Anterior and posterior head and neck, 9% Anterior and posterior upper limbs, 18% Anterior and posterior 41/2% 41/2% trunk, 36% Anterior trunk, 18% Perineum, 1% 9% 9% Anterior and posterior lower limbs, 36% 100% (a) © 2012 Pearson Education, Inc. Figure 4.11a  Severity of Burns First-degree burns Only epidermis is damaged Skin is red and swollen Second-degree burns Epidermis and upper dermis are damaged Skin is red with blisters Third-degree burns Destroys entire skin layer; burned area is painless Burn is gray-white, cherry red or blackened Little or no edema © 2012 Pearson Education, Inc.  Critical Burns Burns are considered critical if Over 25 percent of body has second-degree burns Over 10 percent of the body has third- degree burns There are third- degree burns of the face, hands, or feet © 2012 Pearson Education, Inc.  Skin Cancer Cancer—abnormal cell mass Classified two ways Benign Does not spread (encapsulated) Malignant Metastasized (moves) to other parts of the body Skin cancer is the most common type of cancer © 2012 Pearson Education, Inc.  Skin Cancer Types Basal cell carcinoma Least malignant Most common type Arises from stratum basale © 2012 Pearson Education, Inc.  Skin Cancer Types Squamous cell carcinoma Metastasizes to lymph nodes if not removed Early removal allows a good chance of cure Believed to be sun- induced Arises from stratum spinosum © 2012 Pearson Education, Inc.  Skin Cancer Types Malignant melanoma Cancer of melanocytes Most deadly of skin cancers Metastasizes rapidly to lymph and blood vessels Detection uses ABCD rule © 2012 Pearson Education, Inc.  ABCD Rule A =Asymmetry Two sides of pigmented mole do not match B = Border irregularity Borders of mole are not smooth C = Color Different colors in pigmented area D = Diameter Spot is larger then 6 mm in diameter © 2012 Pearson Education, Inc.