Integumentary System .

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Integumentary System. Cutaneous membrane (skin) – our largest organ Accounts for 7% of body weight Divided into two distinct layers Epidermis Dermis Accessory structures Subcutaneous layer ( hypodermis ). Functions Of The Integument. Cushions and insulates deeper organs
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Integumentary System Cutaneous film (skin) – our biggest organ Accounts for 7% of body weight Divided into two particular layers Epidermis Dermis Accessory structures Subcutaneous layer ( hypodermis )

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Functions Of The Integument Cushions and protects further organs Protects body from scraped area, injury, chemicals, pathogens, temperature extremes and UV beams Excretion and emission Contains tangible receptors connected with nerve endings Synthesis and capacity of supplements (vitamin D3)

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Integumentary Structures Components of the Integumentary System Figure 5-1

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Skin Structures

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The Epidermis-Four Main Cell Types Melanocytes - found in basal layer, fabricate and discharge shade Merkel cells - basal layer, appended to tactile nerve endings Keratinocytes – Arise from most profound layer of epidermis to stratum spinosum Produce keratin – an intense stringy protein Produce antibodies and catalysts Keratinocytes are dead at skin\'s surface Langerhans cells - stratum spinosum, some portion of invulnerable framework macrophage-like

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The Epidermis Stratified squamous epithelium Several unmistakable cell layers Thick skin—five layers on palms and soles Thin skin—four layers on rest of body

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Layers of The Epidermis Stratum corneum Most shallow layer Dead, leveled (squamous) cells Abundant keratin - Keratinized ( cornified) t ough, water-safe protein Protects skin against scraped spot and entrance Stratum lucidum (clear layer) Occurs just in tough skin – palms and soles Composed of a couple columns of level, dead keratinocytes

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Layers of The Epidermis Stratum granulosum (grainy layer) Consists of keratinocytes Tonofilaments Keratohyaline granules – shape keratin Lamellated granules – contain a waterproofing glycolipid Stratum spinosum (sharp layer) "Spiked" appearance brought on by ancient rarities of histological readiness Contains thick packages of halfway fibers (tonofilaments) Resist strain Contain protein prekeratin Contains star-molded Langerhans cells

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Layers of the Epidermis Stratum basale Deepest layer of epidermis Attached to fundamental dermis Stem cells effectively partition Merkel cells – connected with tactile nerve finishing Melanocytes – emit the shade melanin

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Epidermal Cells and Layers of the Epidermis Figure 5.3

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Sources of Skin Color Melanocytes Make melanin from tyrosine Melanin gives UV insurance Gives rosy cocoa to chestnut dark shading Carotene Contributes orange-yellow shading Provided from eating regimen (carrots and tomatoes) Hemoglobin - blood color Caucasian skin contains little melanin Allows red shade of blood to appear on the other side

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Dermis Second real layer of the skin Provides mechanical quality, adaptability, and assurance for hidden tissues Highly vascular and contains an assortment of tactile receptors that give data about the outside environment Two layers Papillary layer – incorporates dermal papillae Reticular layer - d eeper layer – 80% of thickness of dermis Flexure lines - wrinkles on palms

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Layers of the Dermis Papillary layer Underlies epidermis Named for dermal papillae Aerolar connective tissue Supports, feeds epidermis Provides tangible nerves, lymphatics, and vessels Reticular layer Tough, thick, sinewy layer Dense unpredictable connective tissue Collagen filaments - restrict extend Elastic filaments - give adaptability Blends into papillary layer (above) Blends into subcutaneous layer (beneath)

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Dermal Components Epidermal embellishment organs Cells of connective tissues legitimate Communication with other organ frameworks Cardiovascular Lymphatic Nervous Sensation Control of blood stream and discharge

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Subcutaneous Layer - Hypodermis Composed of free connective tissue - areolar and fat Stabilizes skin position Loosely joined to dermis Loosely appended to muscle Contains numerous fat cells Provides warm protection Cushions basic organs Safely gets hypodermic needles

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Hair Filamentous strands of dead keratinized cells created by hair follicles Contains hard keratin which is harder and more strong than delicate keratin of the skin Chief parts of a hair Root – imbedded in the skin Shaft – extends over skin\'s surface

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Hair Shaft sorted out into three concentric layers Medulla – focal center Cortex – encompasses medulla Cuticle – peripheral layer Pigmented by melanocytes at the base of the hair

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Cross Section of a Hair Figure 5.7a, b

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Hair Follicle Root sheath reaching out from the epidermal surface into the dermis Deep end is extended framing a hair globule Papilla - areola formed space with veins and nerves    Matrix - germinal layer of cells (effectively separating cells) right over the papilla A bunch of tangible nerve endings (a root hair plexus) wraps around every hair knob Bending a hair invigorates these endings, subsequently our hairs go about as touchy touch receptors Arrector pili muscle - b undle of smooth muscle contracts to make hair stand erect

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Longitudinal Section of Follicle Figure 5.7c, d

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Hair Follicles

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Hair Function and Distribution Functions of hair include: Helping to keep up warmth Alerting the body to nearness of bugs on the skin Guarding the scalp against physical injury, warm misfortune, and daylight Hair is disseminated over the whole skin surface aside from Palms, soles, and lips Nipples and segments of the outer genitalia

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Sebaceous Glands (oil organs) Occur over whole body - Except palms and soles Simple alveolar organs Holocrine discharge – whole cell separates to shape discharge Secretes a sleek substance called sebum Most are connected with a hair follicle Functions of sebum Softens and greases up hair and Skin waterproofing Collects soil

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Sweat (Sudoriferous) Glands Two sorts: Eccrine (Merocrine) Most plentiful sweat organ "Genuine sweat" 99% water with a few salts Contains hints of metabolic squanders ~ 2% urea Role in thermoregulation Widely show in skin (up to 500/cm 2 ) Apocrine Odorous emission Absent before pubescence Present in axillary, areolar, butt-centric and genital ranges

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Eccrine (Merocrine) Gland Figure 5.10b

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Nails Scalelike change of epidermis made of hard keratin Parts of the nail Free edge Body - d ense mass of k eratinized cells Root Nail folds Eponychium – fingernail skin

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Skin Injury and Repair Four Stages in Skin Healing Inflammation Blood stream expands Phagocytes pulled in Scab arrangement Cell division and relocation Scar development

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Bleeding happens at the site of harm instantly after the damage, and pole cells in the locale trigger a fiery reaction. Following a few hours, a scab has framed and cells of the stratum germinativum are relocating along the edges of the injury. Phagocytic cells are expelling flotsam and jetsam, and a greater amount of these cells are touching base with the upgraded course in the territory. Coagulating around the edges of the influenced territory mostly disengages the locale. Epidermis Scab Migratory epithelial cells Macrophages and fibroblasts Dermis Sweat organ Granulation tissue Skin Injury and Repair

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After a few weeks, the scab has been shed, and the epidermis is finished. A shallow sadness denote the damage site, however fibroblasts in the dermis keep on creating scar tissue that will slowly hoist the overlying epidermis. One week after the damage, the scab has been undermined by epidermal cells relocating over the meshwork delivered by fibroblast movement. Phagocytic action around the site has practically finished, and the fibrin coagulation is deteriorating. Scar tissue Fibroblasts Skin Injury and Repair

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Skin Injury and Repair Table 5-1

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Aging of the Skin Major Age-Related Changes Injury and contamination increment Immune cells diminish Sun security reduces Skin gets to be dry, textured Hair diminishes, grays Sagging, wrinkles happen Heat misfortune diminishes Repair moderates

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Effects of UV Radiation Beneficial impact - actuates union of vitamin D 3 Harmful impacts Sun copy Wrinkles, untimely maturing Malignant melanoma Basal cell carcinoma

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Types and Growth of Hair Vellus hairs Body hairs of ladies and kids Terminal hairs Hair of scalp Axillary and pubic zone (at adolescence) Hair diminishing and sparseness Due to maturing Male example hairlessness

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Burns Classified by seriousness severe singeing – just upper epidermis is harmed severely charred area – upper piece of dermis is additionally harmed Blisters show up Skin mends with small scarring severe singeing Consume thickness of skin Burned zone seems white, red, or darkened

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Estimating Burns Using the Rule of Nines Figure 5.11a

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Skin Cancer Basal cell carcinoma Least threatening and most regular Squamous cell carcinoma Arises from keratinocytes of stratum spinosum Melanoma A disease of melanocytes The most unsafe kind of skin tumor

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Skin Cancer Squamous cell carcinoma Squamous cell carcinoma Basal cell carcinoma Melanoma Figure 5.12

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The Skin Throughout Life Epidermis Develops from embryonic ectoderm Dermis and hypodermis Develop from mesoderm Melanocytes Develop from neural peak cells

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The Skin Throughout Life Fetal skin Well framed after the fourth month At 5-6 months The baby is secured with lanugo (fleece hairs) Fetal sebaceous organs create vernix caseosa

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The Skin Throughout Life Middle to seniority Skin diminishes and turns out to be less versatile Shows hurtful impacts of natural harm Skin irritations turn out to be more normal

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