Integumentary System PDF

Chapter 5 The Integumentary System Figure 5.1 Skin structure.  Skin (Integument)  Consists of two distinct regions 1. Epidermis—superficial region  Epithelial tissue 2. Dermis—underlies epidermis  Thin layer of Areolar connective tissue  Thick layer of Dense ir...

Chapter 5 The Integumentary System Figure 5.1 Skin structure.  Skin (Integument)  Consists of two distinct regions 1. Epidermis—superficial region  Epithelial tissue 2. Dermis—underlies epidermis  Thin layer of Areolar connective tissue  Thick layer of Dense irregular connective tissue  Hypodermis (superficial fascia) Subcutaneous layer deep to skin Mostly adipose tissue that absorbs shock & insulates Anchors skin to underlying structures – mostly muscles  Figure 5.1 Skin structure. Hair shaft Dermal papillae Epidermis Subpapillary Papillary plexus layer Sweat pore Appendages of skin Dermis Reticular Eccrine sweat gland layer Arrector pili muscle Sebaceous (oil) gland Hair follicle Hair root Hypodermis (subcutaneous tissue; not part of skin) Cutaneous plexus Nervous structures Sensory nerve fiber with free nerve endings Adipose tissue Lamellar corpuscle Hair follicle receptor (root hair plexus) © 2019 Pearson Education, Inc.  Figure 5.2b The main structural features of the skin epidermis. Keratinocytes Stratum corneum Most superficial layer; 20–30 layers of dead cells, essentially flat membranous sacs filled with keratin. Glycolipids in extracellular space. Stratum granulosum Typically five layers of flattened cells, organelles deteriorating; cytoplasm full of lamellar granules (release lipids) and keratohyaline granules. Stratum spinosum Dendritic Several layers of keratinocytes unified by desmosomes. cell Cells contain thick bundles of intermediate filaments made of pre-keratin. Sensory Stratum basale Dermis nerve Deepest epidermal layer; one row of actively ending mitotic stem cells; some newly formed cells Melanin Tactile become part of the more superficial layers. granule (Merkel) cell See occasional melanocytes and dendritic Desmosomes Melanocyte cells. © 2019 Pearson Education, Inc.  Layers of the Dermis  #1 Papillary Layer:  Composed of Areolar connective tissue  Dermal papillae Some contain Meissner's corpuscles, or free nerve endings In thick skin lie on dermal ridges causing epidermal ridges “friction ridges” Figure 5.4 Dermal modifications result in characteristic skin markings. Figure 5.5 Stretch marks (striae).  Skin Color  Three pigments contribute to skin color  1. Melanin  2. Carotene  3. Hemoglobin  Skin Color in Diagnosis  Cyanosis Blue skin color - low oxygenation of hemoglobin  Erythema (redness) Fever, hypertension, inflammation, allergy  Pallor (blanching) Anemia, low blood pressure, fear, anger  Jaundice (yellow cast) Liver disorder  Bronzing Inadequate steroid hormones in addison's disease (adrenal disorder)  Bruises Clotted blood beneath skin  Jaundice  Three main forms 1. Pre-hepatic-genetic 2. Hepatocellular- in infants, hepatitis, cirrohis 3. Post-hepatic- cancer, gallstones.  Liver/Pancreas © 2019 Pearson Education, Inc.  Hair  Dead keratinized cells of hard keratin  More durable than soft keratin of skin  Not in palms, soles, lips, nipples, portions of external genitalia  Functions include  1.Warn off insects on skin  2. Physical trauma  3. Heat loss  4. Sunlight Figure 5.6 Structure of a hair and hair follicle.  Types and Growth of Hair  Vellus hair Pale, fine body hair of children and adult females  Terminal hair Coarse, long hair of eyebrows, scalp At puberty  Appear in axillary and pubic regions of both sexes  Face and neck of males  Nails Guinness World Records Scalelike modifications of epidermis containing hard keratin that provide a protective cover for distal, dorsal surface of fingers and toes. Figure 5.6 Skin appendages: Structure of a nail. Lunule Lateral nail fold Free edge Body Eponychium Root of nail of nail of nail (cuticle) Proximal Nail nail fold matrix Hyponychium Nail bed Phalanx (bone of fingertip) © 2019 Pearson Education, Inc. Figure 5.8 Koilonychia.  Sweat Glands  Also called sudoriferous glands  All skin surfaces except nipples and parts of external genitalia  ~3 million per person  Two main types  Eccrine (merocrine) sweat glands  2. Apocrine sweat glands  Eccrine Sweat Glands Heat Induced sweating vs. Cold sweat.  Apocrine Sweat Glands  Modified apocrine glands Ceruminous glands- Mammary glands –  Functions of the Integumentary System  1. Protection  2. Body temperature regulation  3. Cutaneous sensation  4. Metabolic functions  5. Blood reservoir  6. Excretion  Protection  Three types of barriers  1. Chemical Barrier  2. Physical Barrier  3. Biological Barrier  Protection: Chemical Barriers  Skin secretions Low pH retards bacterial multiplication Sebum and defensins kill bacteria  Melanin Defense against UV radiation damage  Protection: Physical Barriers  What gives us the physical Barrier?  Limited penetration of skin Lipid-soluble substances(steroids, O2, CO2, Vitamins A,D,E,K) Plant oleoresins (e.g., Poison ivy) Organic solvents(paint thinner, acetone) Salts of heavy metals(Lead and mercury) Some drugs(nitroglycerine, nicotine).  Protection: Biological Barriers  Biological barriers Dendritic cells of epidermis- Macrophages of dermis- DNA-  Functions of the Integumentary System  Body temperature regulation If body temperature normal ~500 ml/day of routine insensible perspiration If body temperature rises, dilation of dermal vessels and increased sweat gland activity causes sensible perspiration Cold external environment  Dermal blood vessels constrict  Skin temperature drops to slow passive heat loss  Functions of the Integumentary System  Cutaneous sensations- exteroreceptors Cutaneous sensory receptors – part of nervous system – detect temperature, touch, and pain  Metabolic functions Synthesis of vitamin D precursor and collagenase Chemical conversion of carcinogens and activate some hormones  Blood reservoir—up to 5% of body's blood volume  Excretion—urea and salt in sweat  Skin Cancer  Most skin tumors are benign and do not metastasize  Risk factors Overexposure to UV radiation Frequent irritation of skin  Three major types of skin cancer  1.  2.  3. Figure 5.8 Photographs of skin cancers. Basal cell carcinoma Squamous cell carcinoma Melanoma ABCD Rule:  Burns  Tissue damage caused by heat, electricity, radiation, certain chemicals  Immediate threat: ?  To evaluate burns Rule of nines Used to estimate volume of fluid loss Figure 5.9 Estimating the extent and severity of burns using the rule of nines.  Burns Classified by Severity  Partial-thickness burns First degree Second degree  Full-thickness burns Third degree Figure 5.10 Partial thickness and full thickness burns.  Severity and Treatment of Burns  Critical if >25% of body has second- degree burns >10% of body has third- degree burns Face, hands, or feet bear third-degree burns  Treatment includes Debridement (removal) of burned skin Antibiotics Temporary covering Skin grafts Figure 5.9 Estimating the extent and severity of burns using the rule of nines.  Development of Tissue Types Embryonic germ layers and the primary tissue types they produce.  Fetal  Ectoderm  epidermis;  Mesoderm  dermis and hypodermis  Lanugo coat: delicate hairs in 5th and 6th month  Vernix caseosa: sebaceous 16-day-old embryo gland secretion; protects skin of (dorsal surface view) fetus  Infancy to adulthood Muscle and connec- tive tissue (mostly  Skin thickens; accumulates from mesoderm) more subcutaneous fat  Sweat and sebaceous gland Epithelium activity increases (from all three  Effects of cumulative germ layers) Nervous tissue Ectoderm environmental assaults show (from ectoderm) Mesoderm after age 30 Inner lining of digestive system  Scaling and dermatitis become Endoderm (from endoderm) more common  Vernix Caseosa Lanugo Hair https://upload.wikimedia.org/wikipedia/commons/d/d6/V%C3%A8rnix.jpg Photo: Lynne Uhring, MD, BabyFaq Lanugo: Causes and Treatment (healthline.com)  Cradle Cap (Seborrhea) in a Newborn Figure 5.10 Cradle cap (seborrhea) in a newborn.  Developmental Aspects  Aging skin Epidermal replacement slows, skin becomes thin, dry and itchy (decreased sebaceous gland activity) Subcutaneous fat and elasticity decrease, leading to cold intolerance and wrinkles Increased risk of cancer due to decreased numbers of melanocytes and dendritic cells Hair thinning