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Skin Functions of Skin Mechanical/Chemical damage – keratin toughens cells; fats cells cushion blows; and pressure receptors to measure possible damage.

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Seven Functions of Skin Mechanical/Chemical damage – keratin toughens cells; fats cells cushion blows; and pressure receptors to measure possible damage.

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Presentation on theme: "Skin Functions of Skin Mechanical/Chemical damage – keratin toughens cells; fats cells cushion blows; and pressure receptors to measure possible damage."— Presentation transcript:

1 Skin Functions of Skin Mechanical/Chemical damage – keratin toughens cells; fats cells cushion blows; and pressure receptors to measure possible damage Mechanical/Chemical damage – keratin toughens cells; fats cells cushion blows; and pressure receptors to measure possible damage Bacterial damage – skin secretions are acidic and inhibit bacteria. Bacterial damage – skin secretions are acidic and inhibit bacteria. Ultraviolet radiation – melanin produced to protect from UV damage Ultraviolet radiation – melanin produced to protect from UV damage

2 Skin Functions Thermal control – regulates body temperature Thermal control – regulates body temperature Heat loss: sweat to cool the skin Heat loss: sweat to cool the skin Heat retention: prevents blood to rush into capillary beds Heat retention: prevents blood to rush into capillary beds Waterproofing – contains lipids to prevent drying out Waterproofing – contains lipids to prevent drying out Excretion of waste – urea and uric acid secreted in sweat Excretion of waste – urea and uric acid secreted in sweat Makes vitamin D – modifies cholesterol molecules in skin and converts it to vitamin D Makes vitamin D – modifies cholesterol molecules in skin and converts it to vitamin D

3 Skin Structure Epidermis outer layer Epidermis outer layer Stratified squamous epithelium Stratified squamous epithelium Often keratinized (hardened by keratin) Often keratinized (hardened by keratin) Dermis Dermis Dense connective tissue Dense connective tissue Subcutaneous tissue Subcutaneous tissue hypodermis hypodermis

4 Skin Structure Summary of layers from deepest to most superficial: Stratum basale Stratum basale Stratum spinosum Stratum spinosum Stratum granulosum Stratum granulosum Stratum lucidum Stratum lucidum Stratum corneum Stratum corneum

5 Skin Structure Subcutaneous tissue (hypodermis) is deep to dermis Subcutaneous tissue (hypodermis) is deep to dermis Not part of the skin Not part of the skin Anchors skin to underlying organs, bones and muscles Anchors skin to underlying organs, bones and muscles Contains half of the bodys fat; acts as padding and insulation. Contains half of the bodys fat; acts as padding and insulation.

6 Layers of the Epidermis Stratum basale Stratum basale Deepest layer of epidermis Deepest layer of epidermis Cells actively undergoing cell division Cells actively undergoing cell division New cells are pushed upward to become the more superficial layers New cells are pushed upward to become the more superficial layers Stratum spinosum – intermediate layer Stratum spinosum – intermediate layer Stratum granulosum – another layer Stratum granulosum – another layer

7 Layers of the Epidermis Stratum lucidum Stratum lucidum Formed from dead cells of the deeper layers Formed from dead cells of the deeper layers Occurs only in thick, hairless skin of the palms of hands and soles of feet Occurs only in thick, hairless skin of the palms of hands and soles of feet Stratum corneum Stratum corneum Outermost layer of epidermis Outermost layer of epidermis Scale-like dead cells are filled with keratin which is a protective protein preventing water loss from skin Scale-like dead cells are filled with keratin which is a protective protein preventing water loss from skin

8 Keratinization Cells migrate to the epidermis where eventually they fall off. Cells migrate to the epidermis where eventually they fall off. As they move upward, keratin is added. As they move upward, keratin is added. The cells in the epidermis contain a lot of keratin which resists damage. The cells in the epidermis contain a lot of keratin which resists damage. Distinct layers of cells are called strata. Distinct layers of cells are called strata. A cell takes ~ 40 – 56 from creation to sloughing off

9 Melanin Pigment (melanin) produced by melanocytes Pigment (melanin) produced by melanocytes Melanocytes are mostly in the stratum basale Melanocytes are mostly in the stratum basale Color is yellow to red to brown to black Color is yellow to red to brown to black Amount of melanin produced depends upon genetics and exposure to sunlight Amount of melanin produced depends upon genetics and exposure to sunlight

10 Melanin continued…. Large amounts of melanin occur in some regions like freckles, moles, and nipples. Large amounts of melanin occur in some regions like freckles, moles, and nipples. Less melanin occurs in the lips, hands, and soles of the feet. Less melanin occurs in the lips, hands, and soles of the feet. All races have the same number of melanoctyes! The amount of melanin produced is determined by genetics. All races have the same number of melanoctyes! The amount of melanin produced is determined by genetics.

11 Albinism A single mutation can cause a deficiency or complete absence of melanin. A single mutation can cause a deficiency or complete absence of melanin. Albinos have fair skin, white hairs, and unpigmented eyes Albinos have fair skin, white hairs, and unpigmented eyes

12 Dermis Two layers Two layers Papillary layer (upper dermal region) Papillary layer (upper dermal region) Projections called dermal papillae Projections called dermal papillae Some contain capillary loops containing blood Some contain capillary loops containing blood Some pain receptors and touch receptors Some pain receptors and touch receptors Reticular layer (deepest skin layer) Reticular layer (deepest skin layer) Blood vessels Blood vessels Sweat and oil glands Sweat and oil glands Deep pressure receptors Deep pressure receptors

13 What causes Normal Skin Color Melanin Melanin Yellow, brown, or black pigments Yellow, brown, or black pigments Carotene Carotene Orange-yellow pigment from some vegetables Orange-yellow pigment from some vegetables Hemoglobin Hemoglobin Red coloring from blood cells in dermal capillaries Red coloring from blood cells in dermal capillaries Oxygen content determines the extent of red coloring Oxygen content determines the extent of red coloring

14 Dermis Overall dermis structure Overall dermis structure Collagen and elastic fibers located throughout the dermis Collagen and elastic fibers located throughout the dermis Collagen fibers give skin its toughness Collagen fibers give skin its toughness Elastic fibers give skin elasticity Elastic fibers give skin elasticity Dermal papillae – extend toward the epidermis and deliver nutrients, remove waste products (sweat = urea and uric acid) and aid in regulating body temperature. Dermal papillae – extend toward the epidermis and deliver nutrients, remove waste products (sweat = urea and uric acid) and aid in regulating body temperature.

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16 What causes Normal Skin Color Melanin Melanin Yellow, brown, or black pigments Yellow, brown, or black pigments Carotene Carotene Orange-yellow pigment from some vegetables Orange-yellow pigment from some vegetables Hemoglobin Hemoglobin Red coloring from blood cells in dermal capillaries Red coloring from blood cells in dermal capillaries Oxygen content determines the extent of red coloring Oxygen content determines the extent of red coloring


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