In the reticular dermis resulting in linear patches

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in the reticular dermis resulting in linear patches on the skin called striae which are also known as stretch marks 67 Dermis Flexure lines Arise from the deep part of the dermis and result from the repeated folding of the skin such as in the palms of your hands and around joints e.g., at the wrist, fingers, and toes 68 Friction ridges (a) Friction ridges of finger tip (SEM 20 × ) (b) Cleavage lines in the reticular dermis (c) Flexure lines of the hand Openings of sweat gland ducts Flexion creases on digit Flexion creases on the palm Dermal Modifications Figure 5.6 69 Hypodermis Deep to the skin—also called superficial fascia • Contains areolar and adipose connective tissue Anchors skin to underlying structures Helps insulate the body Hypodermis is area that can thicken dramatically with development of increased adipose tissue in people with obesity (e.g., adipose deposits in the abdominal wall) 70 Skin Structure Figure 5.1 Epidermis Hair shaft Dermis Reticular layer Papillary layer Hypodermis (superficial fascia) Dermal papillae Pore Subpapillary vascular plexus Appendages of skin Eccrine sweat gland Arrector pili muscle Sebaceous (oil) gland Hair follicle Hair root Nervous structures Sensory nerve fiber Lamellar (Pacinian) corpuscle Hair follicle receptor (root hair plexus) Dermal vascular plexus Adipose tissue 71 Skin burns 72
11/8/12 13 Types of skin burns First-degree burn —only epidermis is damaged Second-degree burn —epidermis and upper part of dermis are damaged resulting in blister formation from separation of the epidermis from the dermis; typically heals with no scar formation Third-degree burn ----Damages entire thickness of skin and produces permanent scar 73 (b) Skin bearing full thickness burn (third-degree burn) 3rd degree burn Estimating Burn Surface Area Using the Rule of Nines Figure 5.10 (a) Skin bearing partial thickness burn (first- and second-degree burns) 1st degree burn 2nd degree burn Anterior and posterior head and neck, 9% 4 1 / 2 % 4 1 / 2 % Anterior and posterior upper limbs, 18% Anterior and posterior lower limbs, 36% 100% (c) Rule of nines; used to estimate extent of burns Totals Anterior values Anterior and posterior trunk, 36% Anterior trunk, 18% 9% 9% (Perineum, 1%) 4 1 / 2 % 74 Rule of nines to estimate body surface Perineum = 1% Total Head = 9% Right upper extremity = 9% Left upper extremity = 9% Anterior trunk = 18% Posterior trunk = 18% Right lower extremity = 18% Left lower extremity = 18 % 75 Tissue Response to Injury 76 Tissue Response to Injury Inflammatory response –Nonspecific, local response –Limits damage to injury site Immune response –Takes longer to develop and very specific –Destroys particular microorganisms at site of infection 77 Tissue response to skin injury Inflammation Acute inflammation –Heat –Redness –Swelling –Pain –Chemicals signal nearby blood vessels to dilate & histamine increases permeability of capillaries producing edema in region 78
11/8/12 14 Tissue response to skin injury Inflammation Edema

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