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Integumentary System

Integumentary System. The Skin. Facts about the skin. Skin is the largest external organ 1mm thick when you’re born Thickens to 2mm as you age Thins as you reach old age Weighs on average between 6-10 lbs Soles of your feet and palms have no hair follicles

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Integumentary System

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  1. Integumentary System The Skin

  2. Facts about the skin • Skin is the largest external organ • 1mm thick when you’re born • Thickens to 2mm as you age • Thins as you reach old age • Weighs on average between 6-10 lbs • Soles of your feet and palms have no hair follicles • Majority of dust in your house is made of skin flakes

  3. Integumentary System Tissues that make up skin • Epithelium of epidermis • Connective tissue of dermis(Dense Irregular CT) • Subcutaneous layer (AKA superficial fascia or hypodermis) Skin is the main organ of integumentary system but also consists of its derivatives • Hair • Nails • Glands • Nerve endings

  4. Layers of the skin

  5. Functions of the Skin • Regulation of body temperature • Protection • Sensation • Excretion • Immunity • Blood reservoir • Vitamin Synthesis

  6. Synthesis of Vitamin D • An hour of sunlight per week is sufficient to activate the body's own vitamin D precursor • The sun triggers cholesterol found in epidermal cells to convert into Vitamin D • Vitamin D can also be consumed in fortified milk. • Vitamin D is essential because it regulates Ca and Phosphorus and keeps skeleton strong • Deficiencies can cause rickets, osteoporosis, osteomalacia

  7. Components of the skin

  8. Surface Film • Protective barrier of skin is formed by a thin film of emulsified material spread on its surface • Made out of sweat, sebum and shed epithelial cells • Functions • Protect against irritants • Antimicrobial • Lubricate, hydrate

  9. Cell of the Epidermis Epidermis is avascular and made up of keratinized stratisfied squamous cells. Keratinocytes • make up 90% of epidermal cells • Principal outer element of the skin • Become filled with tough fibrous keratin Melanocytes • Contribute to color of skin • Keep UV light from penetrating deep Langerhans cells • Play a role in immune defense • Function with white blood cells

  10. Epidermis The epidermis is made up of five sub-layers: • Basal layer (stratum basale) The basal layer is the inner layer of the epidermis, containing basal cells. Basal cells continually divide, forming new keratinocytes and replacing the old ones that are shed from the skin's surface. • Spinous layer (stratum spinosum) So named because after preservation, tissue looks to have “spines.” These are desmosomes being formed to connect the epithelial cells. • Granular layer (stratum granulosum) So named because they appear as grains under magnifications. Here the cells are beginning to deteriorate as keratin is forming inside of them. Granules are called keratohyalin. • Clear Layer (stratum lucidum) So named because it is a clear layer of cells as they loose their cytoplasmic contents and become fully keratinized. Thicker skin has more of these cells, absent in thin skin. • Horny layer (stratum corneum)This layer contains continually shedding, dead keratinocytes (the primary cell type of the epidermis). This is the dead skin that you shed. It makes up 70 -80% of the dust in your house.

  11. Layers of Epidermis Stratum Germinativum (growth layer)

  12. Dermal-Epidermal Junction • Cements epidermis to dermis • Polysaccharide gel holds layers together • Any large detachment can result in severe infection and death

  13. DermisThe dermis is the middle layer of the skin. The dermis is made up two layers • The papillary layer is areolar connective tissue containing fine elasticfibers, dermal papillae and corpuscles of light touch (Meissner'scorpuscles). 2. The reticular layer is irregular connective tissue containing collagenand elastic fibers. • blood vessels (body temp) • lymph vessels • hair follicles • sebaceous (oil) glands • sweat glands(ducts of sudoriferous) • Adipose tissue

  14. Papillary Layer • Dermal papillae- bumps which form on superficial layer of the dermis • In thick skin papillae line up in parallel lines which epidermis binds to, forming finger and toe prints • In thin skin papillae are randomly placed so no ridges form.

  15. Reticular Layer • Tough layer of thick white collagenous fibers • Few elastic fibers • Attachment point of skeletal and smooth muscles • Arrector pili muscles attach to each hair follicle, give you goose bumps • Sensory receptors are located in this layer

  16. Growth and Repair of Dermis • Strength, extensibility, and elasticity are provided to the skin by collagen and elastin. • Lines of cleavage (tension lines) indicate the direction of collagen fiber bundles in the dermis and are considered in making surgical incisions. • Flexure lines- deep attachment of skin to muscles. Causes deep wrinkles. Langer's cleavage lines

  17. Growth and Repair of Dermis Scars • Fibroblasts reproduce to heal a wound resulting in a mass of connective tissue Stretch Marks • If elastic fiber are stretched too much or too quickly they tear

  18. Subcutaneous-superficial fascia-hypodermis • The subcutis is the deepest layer and is also known as the subcutaneous layer. • The subcutis, consisting of a network of collagen and fat cells, helps conserve the body's heat while protecting other organs from injury by acting as a "shock absorber."

  19. Appendages of the Skin Hair • Follicles develop before birth • Lanugo is hair that forms before birth • Vellus hair-strong fine hair that covers the body(peach fuzz) • Terminal Hair- forms pubic, under arm hair • In males terminal hair replaces vellus hair on extremities, chest and beard

  20. Germinal matrix is highly mitotic and pushes cells up to form hair • Melanocytes are deposited into hair to give it color Germinal Matrix

  21. Male Pattern Baldness Alopecia • Two conditions need to me met • Genes for baldness, polygenic • Sex influenced • Male Hormone testosterone

  22. Appendages of the Skin GLANDS • Sebaceous (oil) glands are usually connected to hair follicles, they areabsent in the palms and soles. • produce sebum, which moistens hair, waterproofsand softens skin, and inhibits bacterial growth. • Enlarged sebaceous glands may produce blackheads, pimples, andboils. • Ceruminous glands • modified sebaceous glands that produce awaxy substance called cerumen. They are found in the externalauditory meatus.

  23. Appendages of the Skin GLANDS • Sudoriferous (sweat) glands-produce perspiration, maintains temperature, eliminates small amounts of wastes. • Eccrine(merocrine)- small sweat glandsfound all over, most abundant, not associated with hair. • Apocrine(stinky) limited in distribution to the skin of theaxilla, pubis, anal, and areola; ducts open into hair follicles.

  24. Appendages of the Skin Nails • Nails are hard, keratinized epidermal cells over the dorsal surfaces ofthe terminal portions of the fingers and toes. • The principal parts of the nail are the body, free edge, root, lunula,eponychium, and matrix • Lunula is latin for “little moon”

  25. The Nail Eponychium(cuticle) Nail plate(body)

  26. Thermoregulation • Body temperature fluctuates very throughout the day. • You’re at the highest at days end and lowest in the morning • Biochemical reactions and enzymes function within a narrow range • Hypothalamus is the body’s thermostat

  27. Abnormal Body Temperature Heat Exhaustion • Body temperature remains normal • Loss of large amount of fluids and electrolytes • Vertigo, nausea and loss of consciousness Heat Stroke • Body temp rises above 105 F • Tacycardia(rapid heart rate) • Hot dry skin • Confusion, convulsions • Body must be cooled immediately or death can result Hypothermia • Body temp below 95 F • Slowed heart rate • Treated by slowly warming persons body Frosbite • Damage results from ice crystals forming in skin • Necrosis results and if left gangrene can set in

  28. Disorders of the Skin Albinism • Every race has about the same number of melanocytes • Skin color is determined by the amount of melanin produced(genetic) • Carotene, yellow pigment that also contributes to skin color(fat cells) • The enzyme tyrosinase is needed to create melanin • Sun exposure cause melanocyte to produce more melanin • In albinism tyrosinase is absent thus they lack pigment in hair, skin and eyes

  29. Disorders of the Skin Epidermolysis bullosa Mutation in the keratin gene. Epidermis and dermis is not held together. any friction causes them to separate and leave open sores and blister. Cases can range from mild to severe. Bone marrow transplants have proven beneficial.

  30. Disorders of the Skin Vitiligo • Charaterized by white patches of skin • Melanocytes no longer produce pigment

  31. Disorders of the Skin Onycholysis • Seperation of nails from the nail bed • Usually occurs after trauma to nail

  32. Disorders of the Skin Impetigo • Caused by staph or strep infections • Blisters with yellowish or dark scabs Tinea • Fungal infections • Ringworm, athletes foot, thrush, jock itch Warts • Bumpy projections caused by papilloma viruses • Easily removed Boils • Staph infection of follicles • Large pus filled lesions

  33. Disorders of the Skin Acne • Result of overactive secretion of sebaceous glands(5-10X more than normal) • Pores are clogged and can form infected pustules Blisters • Desmosomes are damaged by injury or irritation • Immune response to protect skin Calluses • Hardened skin formed by continual pressure/rubbing Corns • Thick hardened skin usually form in bony areas as a result of friction

  34. Burns Can be caused by heat, electricity, UV rays or chemicals First Degree • Only the epidermis is damaged, sunburns normally are first degree Second Degree • Epidermis and top layer of dermis are damaged, blisters form, may have shiny appearance Third Degree • Entire depth of skin destroyed, black or grayish in color. Skin cannot heal itself, graphs normally needed

  35. First Degree Second Degree Third Degree

  36. “rule of nines” • Used to estimate the amount of skin burned

  37. Skin Cancermost prevalent type of cancer Non-Malignant Malignant(cancerous) Melanoma can show up anywhere on the body Metastasizes easily Severe burns increase your risk • Basal Cell Carcinoma • Squamous Cell Carcinoma • These two account for 95% of all skin cancers. • Rarely metastasize • Show up on sun exposed areas • Lifetime daily exposure to sun

  38. Basal Cell Carcinoma Squamous Cell Carcinoma

  39. Malignant Melanoma

  40. Prevention • Limit exposure to sun • Wear sunscreen • Screen body monthly

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