The Integumentary System Vocabulary Important Info Headings 1
General Anatomy A large organ composed of all 4 tissue types 22 square feet 1-2 mm thick Weight 10 lbs. 2 Major layers of skin Epidermis is epithelial tissue only Dermis is layer of connective tissue, nerve & muscle Subcutaneous Tissue (Hypodermis) (subq or hypodermis) is layer of adipose & areolar tissue 2 subq = subcutaneous injection intradermal = within the skin layer
General Functions of the Skin Regulation of body temperature Protection as physical barrier Sensory receptors Excretion and absorption Synthesis of vitamin 3
Thermoregulation Releasing of sweat onto the skin perspiration & its evaporation lowers body temperature Adjusting flow of blood to the body surface in moderate exercise, more blood brought to surface helps lower temperature with extreme exercise, blood is shunted to muscles and body temperature rises Shivering and constriction of surface vessels 4 raise internal body temperature as needed The above pictures are thermographs. They reveal the temperature variation around the body. The red and yellow areas are the hottest, while the green and blue areas are cold.
Protection Physical, chemical and biological barrier 5 tight cell junctions prevent bacterial invasion Lipids released hinder evaporation Melanin & other pigment protect somewhat against UV light Langerhans cells alert immune system
Cutaneous Sensations of Skin 6 Mechanoreceptor Thermoreceptor Pacinian Corpuscle Merkel Cells Nociceptor Nociceptor Touch Temperature Pressure Vibration Tickling Some Pain sensations
Absorption Excretion 7 Only a minor role is played by skin 400 ml evaporates daily Small amounts salt, CO2, ammonia and urea excreted Lipid soluble substances can be absorbed through the skin vitamins A, D, E and K, Oxygen and CO2 acetone and dry-cleaning fluid, lead, mercury, arsenic, poisons in poison ivy and oak
Transdermal Drug Administration Method by which drugs in a patch enter the body Drug absorption most rapid where skin is thin (scrotum, face and scalp) Examples 8 nitroglycerin (prevention of chest pain from coronary artery disease) scopolamine (motion sickness) estradiol (estrogen replacement therapy) nicotine (stop smoking alternative)
Synthesis of Vitamin D Not a vitamin at all = Prohormone 9 Sunlight activates a precursor to vitamin D Enzymes in the liver & kidneys transform that molecule into calcitriol (most active form of vitamin D) Necessary vitamin for absorption of calcium from food in the gastrointestinal tract
Synthesis of Vitamin D Not a vitamin at all = Pro-hormone Calcidiol Calcitriol About 80 % of vitamin D used in the body is produced when sunlight reacts with 7-dehydrocholesterol, a precursor sterol (cholesterol) in the skin, producing vitamin D3 or Cholecalciferol. The liver then metabolizes vitamin D3 into 25-hydroxycholecalciferol or Calcidiol, the main form of vitamin D circulating in the blood. The kidney, functioning as an endocrine gland, converts this precursor into two principal dihydroxylated metabolites or Calcitriol, the primary active form of vitamin D transported to various target organs: 10 bone, intestines, kidneys, where it binds to receptors and carries out further biochemical actions.
Epidermis 11 Stratified squamous epithelium Contains no blood vessels 4 types of cells 5 distinct strata (layers) of cells
Cell types of the Epidermis Keratinocytes--90% Melanocytes-----8 % produces melanin pigment melanin transferred to other cells with long cell processes Langerhan cells produce keratin from bone marrow provide immunity Merkel cells 12 in deepest layer form light touch receptor with sensory neuron
Layers (Strata) of the Epidermis 13 Stratum corneum Stratum lucidum Stratum granulosum Stratum spinosum Stratum basale
Stratum Basale 14 Deepest single layer of cells Called stratum germinativum Combo of merkel cells, melanocytes, keratinocytes & stem cells that divide repeatedly Cells attached to each other & to basement membrane by desmosomes & hemidesmosomes
Stratum Spinosum 15 8 to 10 cell layers held together by desmosomes During slide preparation, cells shrink and look spiny Melanin (pigment protein) taken in by phagocytosis from nearby melanocytes
Stratum Granulosum 16 3-5 layers of flat dying cells Show nuclear degeneration Contain dark-staining keratohyalin granules Contain lamellar granules that release lipid that repels water
Stratum Lucidum 17 Seen in thick skin on palms & soles of feet Three to five layers of clear, flat, dead cells Contains precursor of keratin
Stratum Corneum A SECTION OF THE STRATUM CORNEUM WITH AN INTACT BARRIER FUNCTION With the barrier 'intact' the opportunities for water loss is much less. 18 25 to 30 layers of flat dead cells filled with keratin and surrounded by lipids Continuously shed Barrier to light, heat, water, chemicals & bacteria Friction stimulates callus formation
Keratinization & Epidermal Growth Stem cells divide to produce keratinocytes As keratinocytes are pushed up towards the surface, they fill with keratin 4 week journey unless outer layers removed in abrasion Hormone EGF (epidermal growth factor) can speed up process Psoriasis = chronic skin disorder 19 cells shed in 7 to 10 days as flaky silvery scales abnormal keratin produced
Dermis Connective tissue layer composed of collagen & elastic fibers, fibroblasts, macrophages & fat cells Contains hair follicles, glands, nerves & blood vessels Major regions of dermis 20 papillary region reticular region
Papillary Region Top 20% of dermis Composed of loose CT & elastic fibers Finger like projections: Dermal Papillae Gives rise to Friction Ridges = Fingerprints Functions 21 anchors epidermis to dermis contains capillaries that feed epidermis contains Meissner s Corpuscles (touch) & free nerve endings (pain & temp)
Reticular Region Dense irregular connective tissue Contains interlacing collagen and elastic fibers Packed with oil glands, sweat gland ducts, fat & hair follicles Provides strength, extensibility & elasticity to skin stretch marks are dermal tears from extreme stretching Epidermal ridges form in fetus as epidermis conforms to dermal papillae 22 fingerprints are left by sweat glands open on ridges increase grip of hand
Hypodermis (Subcutaneous Region) Deepest layer Missing on eyelids, nipples, genitals, and shins. Insulator Shock absorber conserving body heat protecting internal organs from injury Stores fat as an energy reserve incase extra calories are needed to power the body The blood vessels, nerves, lymph vessels, and hair follicles 23 also cross through this layer.
Skin Color Pigments Melanin produced in epidermis by melanocytes same # of melanocytes in everyone, but differing amounts of pigment produced results vary from yellow to tan to black color melanocytes convert tyrosine to melanin Carotene in dermis UV in sunlight increases melanin production yellow-orange pigment (precursor of vitamin A) found in stratum corneum & dermis Hemoglobin 24 red, oxygen-carrying pigment in blood cells if other pigments are not present, epidermis is translucent so pinkness will be evident
Clinical observations 25 freckles or liver spots = melanocytes in a patch albinism = inherited lack of tyrosinase; no pigment vitiligo = autoimmune loss of melanocytes in areas of the skin produces white patches
Skin Color as Diagnostic Clue Jaundice Cyanotic yellowish color to skin and whites of eyes buildup of yellow bilirubin in blood from liver disease bluish color to nail beds and skin hemoglobin depleted of oxygen looks purple-blue Erythema redness of skin due to enlarged capillaries in dermis during inflammation, infection, allergy or burns 26 Stop
Accessory Structures of Skin Functions of Hair Prevents heat loss Decreases sunburn Eyelashes help protect eyes Touch receptors (hair root plexus) senses light touch 27 Epidermal derivatives Cells sink inward during development to form: hair oil glands sweat glands nails
Structure of Hair Shaft visible medulla, cortex & cuticle HS round in straight hair HS oval in wavy hair Root below the surface Follicle surrounds root external root sheath internal root sheath base of follicle is bulb 28 blood vessels germinal cell layer
Hair Related Structures Arrector pili smooth muscle in dermis contracts with cold or fear. forms goosebumps as hair is pulled vertically Hair root plexus 29 detect hair movement
Hair Growth Growth cycle growth stage & resting stage Growth stage lasts for 2 to 6 years matrix cells at base of hair root producing length Resting stage lasts for 3 months matrix cells inactive & follicle atrophies Old hair falls out as growth stage begins again 30 normal hair loss = 70-100 hairs per day
Hair Color Result of melanin produced in melanocytes in hair bulb Dark hair = true melanin Blond and Red = melanin with iron and sulfur added Graying = decline in melanin production White hair = air bubbles 31in medullary shaft
Sebaceous (oil) glands Secretory portion in the dermis Most open onto hair shafts Sebum combination of cholesterol, proteins, fats & salts keeps hair and skin soft & pliable inhibits growth of bacteria & fungi (ringworm) Acne 32 bacterial inflammation of glands secretions stimulated by hormones at puberty
Sudoriferous (Sweat) Glands Eccrine (sweat) glands most areas of skin secretory portion in dermis with duct to surface regulate body temperature with perspiration Apocrine (sweat) glands armpit and pubic region secretory portion in dermis with duct that opens onto hair follicle secretions more viscous 33 (milky)
Ceruminous glands Modified sweat glands produce waxy secretion in ear canal Cerumin contains secretions of oil and wax glands Helps form barrier for entrance of foreign bodies Impacted cerumen may 34reduce hearing
Structure of Nails Tightly packed, keratinized cells Nail body Nail root 35 stratum corneum layer Nail Matrix deep to the nail root where growth occurs Growth is 1mm per week--faster in summer & on most-used hand buried under skin layers Lunula is white due to thickened stratum basale Eponychium (cuticle) visible portion pink due to underlying capillaries free edge appears white
Types of Skin Thin skin covers most of body epidermis (.1 to.15 mm.) lacks stratum lucidum lacks epidermal ridges, has fewer sweat glands and sensory receptors Thick skin 36 only on palms and soles epidermis (.6 to 4.5 mm.) with distinct stratum lucidum & thick stratum corneum lacks hair follicles and sebaceous glands
Epidermal Wound Healing 37 Abrasion or minor burn Basal cells migrate across the wound Contact inhibition with other cells stops migration Epidermal growth factor stimulates cell division Full thickness of epidermis results from further cell division
Deep Wound Healing If an injury reaches dermis, healing occurs in 4 phases 1. Inflammatory Phase has clot unite wound edges and WBCs arrive from dilated and more permeable blood vessels 2. Migratory Phase begins the regrowth of epithelial cells and the formation of scar tissue by the fibroblasts 3. Proliferative Phase is a completion of tissue formation 4. Maturation Phase sees the scab fall off 38
Which phases have been left out of this illustration? (TRY NOT TO LOOK AT YOUR NOTES!) 39
Scar Formation Hypertrophic Scar remains w/in the boundaries of the original wound Keloid Scar extends into previously normal tissue collagen fibers are very dense and fewer blood vessels are present so the tissue is lighter in color 40 At the superior hole of this navel piercing there is a bead of hypertrophic scar tissue. This is a common complication of all piercings. It is usually a consequence of infection and/or trauma. Typical example of hypertrophic scarring. Often called polyps. This is not a keloid, which is more pale in colour and softer too touch
Pressure Sores 41 Decubitus ulcers Caused by constant deficiency of blood flow to tissue Areas affected is skin over bony prominence in bedridden patients Preventable with proper care
Development of the Skin Epidermis develops from ectodermal germ layer Dermis develops from mesodermal germ layer at 8 weeks, fetal skin is simple cuboidal epithelium nails begin to form at 10 weeks Nails do not reach the fingertip until the 9th month dermis forms from mesoderm by 11 weeks by 16 weeks, all layers of the epidermis are present oil and sweat glands form in 4th and 5th month by 6th months, delicate fetal hair (Lanugo) has formed Slippery coating of oil and sloughed off skin called vernix caseosa is present at birth 42 Large amounts of vernix on babies feet, baby not yet rubbed down, baby approximately 60 seconds out of womb.
Burns Destruction of proteins of the skin chemicals, electrical, heat Different types of burns 1 Epidermis skin layer 2 Dermis skin layer 3 Hypodermis skin layer 4 First degree burn 5 Second degree burn 6 Third degree burn 43
RULE OF 9 s Way to determine the extent of burns Body is divided into 11 areas for quick estimation Each area represents about 9% of total body surface area Problems that result 44 shock due to water, plasma and plasma protein loss circulatory & kidney problems from loss of plasma bacterial infection
Types of Burns First-degree Burn Second-degree Burn destroys entire epidermis & part of dermis fluid-filled blisters separate epidermis & dermis epidermal derivatives are not damaged heals without grafting in 3 to 4 weeks & may scar Third-degree or full-thickness 45 only epidermis (sunburn) destroy epidermis, dermis & epidermal derivatives damaged area is numb due to loss of sensory nerves 1ST 2ND 3RD
Skin Grafts New skin can not regenerate if stratum basale and its stem cells are destroyed Skin graft is covering of wound with piece of healthy skin autograft from self isograft from twin autologous skin 46 Continually evolving techniques for wound healing and tissue repair offer patients expanded opportunities for favorable outcomes. transplantation of patients skin grown in culture STOP
Age Related Structural Changes Collagen fibers decrease in number & stiffen Elastic fibers become less elastic Fibroblasts decrease in number Langerhans cells and macrophages decrease in number and become less-efficient phagocytes Oil glands shrink and the skin becomes dry Walls of blood vessels in dermis thicken so decreased nutrient availability leads to thinner skin 47as subcutaneous fat is lost
Photodamage Ultraviolet light (UVA and UVB) 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 & elastic fibers 48 lead to wrinkling of the skin
Skin Cancer 1 million cases diagnosed per year 3 common forms of skin cancer Basal Cell Carcinoma (rarely metastasize) Squamous Cell Carcinoma (may metastasize) Malignant Melanomas (metastasize rapidly) 49 most common cancer in young women arise from melanocytes ----life threatening!!! key to treatment is early detection watch for changes in Asymmetry, Border, Color and Diameter risks factors include-- skin color, sun exposure, family history, age and immunological status
http://www.skincancerguide.ca/early_detection_skin _cancer.html I had this mole removed due to which danger A,B,C, and/or D? 50