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Chapter 9: Burns

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Which of the following cell types are found in the dermis?

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(A) Fibroblasts

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(B) Langerhans

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(C) Keratinocytes

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(D) Merkel cells

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(E) Melanocytes

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(A) The skin is the largest organ of the body and is composed of three distinct layers: the epidermis, the dermis, and the subcutaneous tissue. The epidermis is the most superficial layer and is composed of four separate layers: the basal layer, the stratum spinosum, the stratum granulosum, and the dead epidermis, the stratum corneum.

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The basal layer is the innermost layer and contains mitotically active keratinocytes. Melanocytes are found within the basal layer and provide ultraviolet radiation protection. In the stratum spinosum, the keratinocytes become more differentiated and are joined together by gap junctions that allow for cellular communication. The stratum granulosum is the most highly differentiated layer of the epidermis and is where most keratin production occurs. Most superficial is the stratum corneum, the outside nonliving layer, which is composed of keratin and provides the major barrier to the environment. Found scattered throughout the epidermis are Langerhans cells, which are important in antigen-processing cells, and Merkel cells, which serve as touch receptors.

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The epidermis and dermis are separated by the basement membrane zone. Anchoring fibrils connect these two layers. The dermis consists of a superficial thin layer called the papillary dermis and a deep, dense layer called the reticular dermis. The primary cell of the dermis is the fibroblast that produces the collagen, elastic fibers, and ground substance that compose the bulk of the dermis. Inflammatory cells migrate through the ground substance beneath the dermis, a large plexus of arterioles and venules called the subdermal plexus. This plexus further branches into superficial smaller vessels called the papillary plexus. The skin appendages, sebaceous glands, sweat glands, and hair follicles all lie within the dermis.

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The subcutaneous layer lies beneath the dermis. This layer contains fat cells that serve as an insulating layer for the body and supports blood vessels and nerves that travel into the dermis (see Fig. 9-1).

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FIGURE 9-1. Layers of the skin. From Demling RH. Burns and other injuries. In: Doherty GM (ed.), Current Diagnosis & Treatment: Surgery, 13th ed. New York, NY: McGraw-Hill; 2010:Chapter 14.

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BIBLIOGRAPHY

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Lewis G, Heimbach D, Gibran N. Evaluation of the burn wound: management decisions. In: Herndon D (ed.), Total Burn Care, 4th ed. London, United Kingdom: W.B. Saunders; 2012:125–135.

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Watson K. Structure of the skin. In: Hall J, Hall B (eds.), Sauer’s Manual of Skin Diseases, 10th ed. ...

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