Presentation on theme: "The Integumentary System Day 1 (scroll down to day 2)"— Presentation transcript:
1The Integumentary System Day 1 (scroll down to day 2)
2The Integumentary System Integument is skinSkin and its appendages make up the integumentary systemA fatty layer (hypodermis) lies deep to itTwo distinct regionsEpidermisDermis
3Functions of skin Protection Regulates body heat Cushions and insulates and is waterproofProtects from chemicals, heat, cold, bacteriaScreens UVRegulates body heatSensory reception (nerve endings)Prevents unnecessary water loss and excretes small amounts of metabolic waste.Synthesizes vitamin D with UV
4Keratinized stratified squamous epithelium Four types of cells EpidermisKeratinized stratified squamous epitheliumFour types of cellsKeratinocytes – deepest, produce keratin (tough fibrous protein)Melanocytes - make dark skin pigment melaninMerkel cells – associated with sensory nerve endingsLangerhans cells – macrophage-like dendritic cells(see figure on next slide)
5Epithelium: layers (on left) and cell types (on right) Desmosomes are molecular complexes of cell adhesion proteins and linking proteins that attach the cell surface adhesion proteins to intracellular keratin cytoskeletal filaments.
6Epidermis Layers (from deep to superficial) Stratum basale (bas= latin for bottom/base) – single row of cells attached to dermis; youngest cellsStratum spinosum (spin =latin for spiny) –mulitlayered cuboidal cells. Molecular bridges are spiny.Dark nucleipynknosisindication of cell death(see figure on next slide)
7Epithelium: layers (on left) and cell types (on right)
8Epidermis Layers (from deep to superficial) continued Stratum granulosum (latin= small grains) – 3-5 layers of flattened keratinocytes producing keratin (hair and nails made of it also)Stratum lucidum (latin= clear/transparent) - only on palms and soles. 3-5 layers of flat dead cells.Stratum corneum – horny layer (cells dead, many layers thick, rows). Sloughed off by normal wear and tear.(see figure on next slide)
9Epithelium: layers (on left) and cell types (on right)
10Epidermis ContinuedFrom stratum basale to slough in approximately 3 weeks.Keratin prevents water lossHowever the barrier is NOT absoluteExample: hot tub internal H20surfacewrinkle
11Skin Color Primarily an inherited trait Secondarily regulated by the pituitary glandMelanocyte (greek=melano=dark) located in basal layer, produces melanin.Color of skin is determined by amount of melanin secreted NOT the number of melanocytes.
13Yesterday you should have been able to answer… What are the five major functions of the integumentary system?Why do cells die as they are pushed farther from the stratum basale?What factors determine the color of your skin?
14Today you will be able to answer… How is the dermis different from the epidermis?What role do blood vessels play in the dermis?How can you distinguish between the two areas of dermis?What product does a sebaceous gland secrete and what is its function?How may the two types of sweat glands be distinguished?What general function is performed by the skin receptors?
15Remember… Four basic types of tissue Epithelium – epidermis just discussedConnective tissue - dermisMuscle tissueNervous tissue
16Dermis Strong, flexible connective tissue: your “hide” Cells: fibroblasts, macrophages, mast cells, WBCsFiber types: collagen, elastic, reticularRich supply of nerves and vesselsCritical role in temperature regulation (the vessels)Two layers (see next slides)Papillary – areolar connective tissue; includes dermal papillaeReticular – “reticulum” (network) of collagen and reticular fibers
18Epidermis and dermis of (a) thick skin and (b) thin skin (which one makes the difference?)
19Fingerprints, palmprints, footprints Dermal papillae lie atop dermal ridgesElevate the overlying epidermis into epidermal ridgesAre “sweat films” because of sweat poresGenetically determinedFlexion creasesDeep dermis, from continual foldingFibersCollagen: strength and resilienceElastic fibers: stretch-recoilStriae: stretch marksTension lines (or lines of cleavage)The direction the bundlesof fibers are directedThe dermis is the receptive site for the pigment of tattoos
20Hypodermis “Hypodermis” (Gk) = below the skin “Subcutaneous” (Latin) = below the skinAlso called “superficial fascia”“fascia” (Latin) =band; in anatomy: sheet of connective tissueFatty tissue which stores fat and anchors skin (areolar tissue and adipose cells)Different patterns of accumulation(male/female)
21Skin appendages Derived from epidermis but extend into dermis Include Hair and hair folliclesSebaceous (oil) glandsSweat (sudoiferous) glandsNails
23Nails Of hard keratin Corresponds to hooves and claws Grows from nail matrix
24Hair and hair follicles: complex Derived from epidermis and dermis Everywhere but palms, soles, nipples, parts of genitalia*“arrector pili” is smooth muscle*Hair bulb: epithelial cells surrounding papillaHair papillais connective tissue________________
25Make up of hair – hard keratin Three concentric layers Functions of hairWarmth – less in man than other mammalsSense light touch of the skinProtection - scalpPartsRoot imbedded in skinShaft projecting above skin surfaceMake up of hair – hard keratinThree concentric layersMedulla (core)Cortex (surrounds medulla)Cuticle (single layers, overlapping)
26Hair growth: averages 2 mm/week Types of hairVellus: fine, short hairsIntermediate hairsTerminal: longer, courser hairHair growth: averages 2 mm/weekActive: growingResting phase then shedHair lossThinning – age relatedMale pattern baldnessHair colorAmount of melanin for black or brown; distinct form of melanin for redWhite: decreased melanin and air bubbles in the medullaGenetically determined though influenced by hormones and environment
27Sebaceous (oil) glands Entire body except palms and solesProduce sebum by holocrine secretionOils and lubricates
28Sweat glandsEntire skin surface except nipples and part of external genitaliaPrevent overheating500 cc to 12 l/day! (is mostly water)Humans most efficient (only mammals have)Produced in response to stress as well as heat
29Types of sweat glands Eccrine or merocrine Apocrine Most numerousTrue sweat: 99% water, some salts, traces of wasteOpen through poresApocrineAxillary, anal and genital areas onlyDucts open into hair follicesThe organic molecules in it decompose with time - odorModified apocrine glandsCeruminous – secrete earwaxMammary – secrete milk