Integumentary System PDF

Chapter 6 Integumentary System  Integumentary System The integument is the skin covering Hair shaft the body. – Aka cutaneous membrane – Dermatology...

Chapter 6 Integumentary System  Integumentary System The integument is the skin covering Hair shaft the body. – Aka cutaneous membrane – Dermatology Sweat pore – Visual indicator of our physiology and health Epidermis Epidermal ridge The integumentary system consists Dermal papilla Papillary of the skin and its derivatives. Integument layer Arrector pili muscle – Nails, hair, sweat glands, sebaceous Sebaceous (oil) gland glands Dermis Reticular Sweat gland duct The integument layer Merocrine sweat gland – Accounts for 8-15% of body weight – Thickness ranges between 1.5 mm and Vein 4.0 mm Artery Subcutaneous layer Adipose connective tissue Hair follicle Tactile Areolar Sensory (sensory) Connective nerve fiber receptors tissue  1. Protection: Acts as a physical barrier from physical injury and trauma 2. Immunity: Initiate immune response against pathogens and cancer cells 3. Skin color 4. Metabolic regulation: Vitamin D synthesis Functions 5. Blood reserve: highly vascular 6. Thermoregulation: sensible perspiration 7. Excretion: water, salt, organic waste, sebum etc. 8. Absorption: selectively permeable. 9. Prevention of water loss: Not absolute – Transpiration – Insensible perspiration 10. General Sensory reception: nerve endings collect various environment stimuli  Epidermal Layers and Cells Variation in thin vs. thick skin – Thick 0.4 to 0.6 mm Dead keratinocytes – Thin - 0.075 to 0.150 mm – Based on layers Stratum corneum Sweat gland duct Cell types Stratum lucidum – Keratinocytes – Melanocytes Stratum granulosum – Tactile cells (Merkel cells) Living keratinocyte – Stratum spinosum Dendritic cells (Langerhans' cells) Melanocyte Keratinization Stratum basale Dendritic cell – resists abrasion and permeability barrier Basement membrane Dermis Tactile cell Desquamation Sensory nerve ending – commonly called skin peeling, is the shedding of the outermost membrane or layer of a tissue (b) 5-4 Stem Cells  Membrane Junctions: Attach Cells Togehter All form from glycoproteins: and anchor with cytoskeleton proteins intracellularly Seal and prevent movement of molecules between cells by forming a barrier. Anchor neighboring cells so they remain attached The channel proteins allow cells to communicate with one another.  Cell division requires abundant nutrients Process of keratinization visible in the strata Keratinization and Desquamation Keratin, keratohyalin, eleidin Keratin is fibrous and as it accumulates, the cells become flatter and their membranes become thickened and less permeable. Keratohyalin dehydrates the cells and precipitates the keratin Tight junctions are strong and remain intact 15-30 days Why do the cells of superficial strata die? Water barrier is created by Keratin; intermediate filament Insoluble protein layer on the inner surface of the keratinocyte PM Lipids secreted by lamellar bodies Tight junctions between keratinocytes Not absolute: Insensible perspiration The barrier is dry and brittle Uninhabitable by most microbes Must be moistened by secretions from glands  Clinical View Psoriasis – Chronic autoimmune disease – Keratinocytes attacked by T-lymphocytes – Causes rapid overgrowth of new skin cells – Cracked, scaly, raw skin – Treatments include corticosteroids, UV light therapy, medications that interfere with skin cell production Increased keratinization due to repeated pressure or friction  Skin Color Determined by pigments and hemoglobin 1. Carotene Yellow-orange pigment Accumulates inside subcutaneous fat and keratinocytes of stratum corneum Plays important roles: – in vision, in reducing free radicals, in epithelial maintenance 2. Hemoglobin: More visible if blood vessels dilate Erythema – abnormal redness Contusion – bruise Cyanosis – blueness: cardiovascular or respiratory disorders Jaundice – yellowness due to bile  Skin Color 3. Melanin – Occurs in black, brown, tan, yellow-brown shades – Melanin in skin varies according to heredity and sun exposure – Everyone has the same number of melanocytes: 1:4 -1:20 ratio of melanocytes in the stratum basale depending on the region of the body Most areas 1000 melanocytes/mm2 but darker areas like nipples, cheeks, forehead, genitalia, etc. have 2000/mm 2 – Pituitary gland releases Melanocyte stimulating hormone (MSH) Melanosomes transferred to keratinocytes in stratum basale Vesicle filled and spinosum with melanin Melanin absorbs UV light Melanin pigment The melanosomes give keratinocytes color until they are in keratinocyte destroyed by fusion with lysosomes. By the time cells slough off, they don’t appear colored. Melanin pigment – Slow increase in response upon greater UV exposure Melanocyte Sunburn results Stratum basale Darker individuals have a better protection against UV Radiation (a) 3. Melanin Nevus Freckles Vitiligo Albinism Tyrosine Melanin Tyrosinase  Skin Cancer Ultraviolet radiation from both the sun and tanning beds can cause. – Sun burn and cancer – Accelerate aging, wrinkles, etc. by preventing the turnover and affecting fibroblasts Sunscreens block UVA and UVB rays. Skin cancer – Most common type of cancer – Mostly occurs on the head and neck – Fair skinned individuals at highest risk – Periodic skin exams recommended – Basal cell carcinoma – Squamous cell carcinoma – stratum spinosum Asymmetric Stage 1 – in the epidermis – Melanoma Bulging border Stage 2 – in the dermis below – Malignant Color Stage 3 – reached the lymph node – Early detection is key to surviving melanoma Diameter Stage 4 – evidence of it’s presence in distant organs – 5 year survival rate may go from 99% to 14% if Evolution metastasis has occurred Actual and Projected Cancer Incidence Rates, United States, 1975 to 2020 Malignant melanomas are a consequence of ozone layer depletion. Increased incident in Australia, US, Europe and Canada. Limit UV exposure – Protective clothing – Sunscreen  Integument: Metabolic Regulation Limited exposure to sunlight is beneficial Vitamin D – Considered a hormone – Important in regulating blood levels of calcium and phosphate – Deficiency leads to impaired bone maintenance and growth and depression – Addition to milk?? – Dressing & Overcast skies??? – Dark skinned vs. light skinned individuals????  Composition of the Integument: Dermis The dermis – Deep to the epidermis Increased contact area – Ranges in thickness from 0.5 mm to 3.0 mm – Composed of connective tissue Epidermal ridges Components of the dermis Dermal – Primarily collagen with elastic and reticular fibers Epidermis papillae – Collagen fibers impart tensile strength Papillary – Elastic fibers allow stretch and recoil layer – Skin Turgor can be a sign of hydrated skin – pinch Dermis test Reticular – Blood vessels, sweat glands, sebaceous glands layer Tactile – Hair follicles, nail roots, sensory nerve endings, receptor arrector pili Artery Vein Subcutaneous layer Areolar CT Adipose CT  Skin Markings Wrinkles Arch Whorl Striae Loop Combination Friction Ridges Tension Lines  Glands Individual cells or multicellular organs Predominantly of epithelial tissue Secrete substances for use elsewhere or for elimination Serous, mucous, or mixed glands – Mucin, electrolytes, hormones, enzymes, and urea Endocrine glands – Lack ducts – Secrete hormone products into interstitial fluid and blood Exocrine glands – Formed from invaginated epithelium in connective tissue – Connected with epithelial surface by duct – Includes sweat glands, mammary glands, salivary glands Unicellular exocrine glands Some organs have both endocrine and exocrine function Shape or branching pattern – Pancreas, liver, gonads, etc.  Classification by Method of Secretion Some sweat glands Mammary glands Sebaceous glands Lacrimal glands Ceruminous glands Salivary glands Some sweat glands in Exocrine glands of the pancreas axillary & pubic Gastric glands of the stomach regions  Glands of the Skin 1.Merocrine sweat glands – Thermoregulation – Provide a means for loss of water and electrolytes - composed of 99% water Sweat – Antibacterial activity pore Sweat gland duct Both of the following glands become active during puberty: 2.Apocrine glands Hair follicle – In axillae, nipples, pubic, and anal region – Produce viscous cloudy secretions Sebaceous gland – contain proteins and lipids Merocrine – produce odor when acted on by bacteria – Pheromones sweat gland 3-methyl-2 hexanoic acid Arrector pili muscle Apocrine 3.Sebaceous glands sweat gland – Secretion stimulated by hormones, especially androgens – Produce oily secretion called sebum – Acts as a lubricant for skin and hair – Has bactericidal properties – Secretions may clog ducts to give rise to acne. (a)  Exocrine Glands of the Skin Sweating is controlled by nervous system – Sensory nerves stimulated myoepithelial cells Sweat glands – Two groups: merocrine and apocrine – General structure Myoepithelial cells Coiled, tubular secretory portion in reticular dermis Sweat gland duct carry secretions Opening of the gland duct on epidermal surface termed sweat pore Contain myoepithelial cells  Dermis Circulation Dermal blood vessels Vasodilation – Supply nutrients to epidermis Hyperthermia and dermis – Large vessels along dermis and hypodermis border – Smaller vessels branch into dermis and dermal papillae – Play an important role in temperature and blood pressure regulation – Skin considered blood reserve – Decubitus ulcer – bed sores form Vasoconstriction by constriction of blood vessels Hypothermia due to pressure Necrotic tissue  Subcutaneous Layer Consists of – Firbroblasts – Adipocytes – Macrophages CT fibers interwoven with those of reticular dermis – Acts as energy reservoir – Pads and protects the body – Provides thermal insulation Drugs often injected here Sexes with different layer thickness and distribution – women, generally thicker primarily in breasts, buttocks, hips, and thighs – men, generally thinner primarily in neck, upper arms, abdomen, lower back, buttocks Hair Follicle  Hair Color and Texture Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Eumelanin Pheomelanin Cuticle Cortex (c) Red, wavy Air Eumelanin space Pheomelanin Medulla (b) Black, straight (a) Blond, straight (d) Gray, wavy  Hair Growth Cycle Growth rate – 1/3 mm per day in the scalp for 2 to 5 years – Enters dormant phase – Eventually pushed out and replaced by new hair 2-6 yrs Hair loss – Normal scalp loss of upto 100 hairs per day – Thinning of hair termed alopecia - diffuse hair loss – Male pattern baldness loss of hair from only some regions of scalp combination of genetic and hormonal factors baldness allele dominant in males and recessive in females expressed only in the presence of high testosterone Hair bulb and papilla Diagnosing disorders like metal poisoning and lead levels (5-6Wks) (1-2 Wks) Eye brows are not a foot long because they have a 30 day growth phase and a 105 days resting period. Anagen : Telogen 80:20 Acne Increased androgen production during puberty Propionibacterium acnes  Sensory Reception Texture Stroking, two point discrimination Pain, itch, tickle, Light pressure and low Temperature frequency vibration Continuous pressure & Light touch stretch of the skin Deep continuous pressure and vibration Fig. 16.2  Repair and Regeneration of the Integumentary System Response to damaged tissues – Regeneration replacement of damaged cells with same cell type Partial thickness burns only Hair follicle can contribute various layers restores organ function – Fibrosis if organ too damaged or cells lack ability to divide gap filled with scar tissue composed primarily of collagen produced by fibroblasts functional activities not restored Joint mobility maybe lowered as well  Stages in Wound Healing Wound Blood clot Epidermis Wound healing Slow Dermis Macrophages Fibroblast Longer for wider and deeper Neutrophils surfaces With severe damage Leukocyte less likely to return to 1 Cut blood vessels bleed into the wound. 2 Blood clot forms, and leukocytes clean wound. original condition Scab Blood clot hair follicles, exocrine glands, nerves, and arrector pili muscle cells not repaired Granulation tissue Regenerated epidermis Macrophages Scar tissue Regrowth of blood vessel (fibrosis) Fibroblast Fibroblast 3 Blood vessels regrow, and granulation tissue forms. 4 Epithelium regenerates, and connective tissue fibrosis occurs.  Burns Caused by heat, radiation, chemical, sunlight, etc. Threat to life from fluid loss, infection, effects of burned tissue First-degree Slight redness, pain, and edema Immerse burned area in cool water Second-degree Skin blistered and painful Slight scarring Growth of epidermis from edges of the wound as well as the accessory organs Third-degree Severe scarring No pain Loss of protection, selective permeability, dehydration, etc. Epidermal growth factor (EGF can be used to grow skin) 5-30  Burns results in Increased capillary Necrosis Heightened permeability Metabolic state Infection Release of hormones E/NE Increased fluid and Resetting of body’s electrolyte loss thermostat Lower blood volume – 101.3 oF Decreased blood Debridement – Loss of 30-40% of delivery to tissue Antibiotics preburn body weight Tissue damage, shock, Tissue grafts death Autografts, isografts, Double or triple the caloric needs and Increased protein to aid in repair allografts Intravenous fluids Necrosis: the death of most or all of the cells in an organ or tissue due to disease, injury, or failure of the blood supply Debridement: the removal of damaged tissue or foreign objects from a wound.  The Rule of Nines Used to estimate – Amount of body surface area that is burned. – Severity of the burn – Severe burns >10% 3rd degree burns >25% 2nd degree burns Damaged hands, face, genitalia Note differing proportions in adult and child. 5-32  Aging Reduced melanocyte activity Local increased melanin production – age spots Reduction in number of layers in epidermal strata Reduced elasticity Increased wrinkling and sagging Decreased production of sweat – heat exhaustion Decreased vitamin D production Skin repair takes longer Senile lentigo – Liver spots