Collectively ridges are called friction ridges Enhance gripping ability

Collectively ridges are called friction ridges

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*Collectively ridges are called friction ridges. *Enhance gripping ability. *Contribute to sense of touch. *Sweat pores in ridges leave unique fingerprint pattern. •Reticular layer; -Deeper, thick dense irregular CT (thick bundles of collagen fibers parallel to skin surface), many elastic fibers, accounting for 80% of the dermis. -Collagen fibers give strength and resiliency and maintain skin hydration; elastic fibers provide stretch-recoil. -Cutaneous plexus: Network of blood vessels between reticular layer and hypodermis. -Extracellular matrix contains pockets of adipose cells. Dermal modifications result in characteristic skin markings •Cleavage (tension) lines in reticular layer are caused by many collagen fibers running parallel to skin surface. -Externally invisible. -Important to surgeons because incisions parallel to cleavage lines heal more readily. •Flexure lines of reticular layer are dermal folds at or near joints. -Dermis is tightly secured to deeper structures. -Skin’s inability to slide easily for joint movement causes deep creases. -Visible on hands, wrists, fingers, soles, toes. Homeostatic imbalances •Striae and Stretch marks: Extreme stretching of the skin can tear the dermis leaving silvery white scars. •Blister: Short term but acute trauma, from a burn or repeated friction causes a fluid-filled pocket that separates the epidermal and dermis layer. The hypodermis •Superficial fascia, subcutaneous tissue. •Areolar CT and blood vessels and adipose tissue. •Functions; 5
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-Anchors skin to underlying structures with ability to slide. -Shock absorber and insulation. -Stores fat. Skin color •Three pigments contribute to skin color; 1.Melanin: Only pigment of the 3 made in the skin; made from tyrosine; several different forms which gives the color yellow, rust, brown, black. -Skin color dependent on type, relative amount and keratinocyte retention of the pigment. -Freckles or pigmented nevi moles: Local accumulations of melanin. -Damage to the skin from the sun causes a substantial melanin buildup to help protect the DNA of skin cells from UV radiation, causes skin to darken. Causes elastic fibers to clump, depresses the immune system, can lead to skin cancer. 2.Carotene: Yellow to orange pigment found in plant products. EX: Carrots deposits in keratinocytes (stratum corneum) and hypodermis. 3.Hemoglobin: From capillary circulation and gives skin a pinkish hue. -Cyanosis: When Hemoglobin is poorly oxygenated, the skin may take on a bluish-gray tint. Can be a sign of respiratory and cardiovascular problems. Accessory structures of the skin •Hair, hair follicles, nails, sweat glands, sebaceous glands; each plays a role in the maintenance of homeostasis. 1.Hair: None on palms, soles, lips, nipples, and portions of external genitalia. -Functions: Sense insects on skin, guard head from physical trauma, heat loss, sun/shield eyes, filter particles from inhaled air.
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