Module 3 Notes.docx - The Integumentary System LECTURE OUTLINE A Introduction 1 Tissues are organized to form an organ and organs are organized to form

Module 3 Notes.docx - The Integumentary System LECTURE...

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The Integumentary System LECTURE OUTLINE A. Introduction 1. Tissues are organized to form an organ, and organs are organized to form systems. 2. The organs of the integumentary system include the skin and its accessory structures including hair, nails, and glands, as well as blood vessels, muscles and nerves. 3. Dermatology is the medical specialty for the diagnosis and treatment of disorders of the integumentary system. B. Structure of the Skin 1. The skin ( cutaneous membrane) covers the body and is the largest organ of the body. 2. It consists of two major layers: i. outer, thinner layer called the epidermis ii. inner, thicker layer called the dermis 3. Beneath the dermis is a subcutaneous (subQ) layer (also called hypodermis ) which attaches the skin to the underlying tissues and organs; the skin and subcutaneous layer form the integument . 4. The epidermis has a number of important characteristics: i. the epidermis is composed of keratinized stratified squamous epithelium ii. it contains four major types of cells: a. 90% of the cells are keratinocytes , which produce keratin ( that provides protection) and lamellar granules (that release a water-repellant sealant) b. melanocytes , which produce the pigment melanin that protects against damage by ultraviolet radiation c. Langerhans cells (or intraepidermal macrophage cells ), which are involved in immune responses d. Merkel cells (or tactile epithelial cells ), which function in the sensation of touch along with the adjacent tactile (or Merkel ) discs iii. the epidermis contains four major layers ( thin skin ) or five major layers ( thick skin ); see: a. stratum basale (deepest layer) or stratum germinativum , where continuous cell division occurs which produces all the other layers b. stratum spinosum , which consists mostly of keratinocytes c. stratum granulosum, which includes keratohyalin and lamellar granules d. stratum lucidum is present only in thick skin (i.e., the skin of the fingertips, palms, and soles) e. stratum corneum (superficial layer), composed of many sublayers of flat, dead keratinocytes called corneocytes or squames that are continuously shed and replaced by cells from deeper strata; constant friction can stimulate formation of a callus iv. keratinization , the accumulation of more and more protective keratin, occurs as cells move from the deepest layer to the surface layer 5. The dermis has several important characteristics: i. the dermis is composed of connective tissue containing collagen and elastic fibers ii. the dermis contains two layers:
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a. the outer papillary region consists of dense connective tissue containing thin collagen and elastic fibers, dermal papillae (including capillary loops ) , corpuscles of touch (Meissner’s corpuscles) , and free nerve endings b. the deeper reticular region consists of dense irregular connective tissue containing collagen and elastic fibers (which provide strength, extensibility, and elasticity to the skin), adipose cells, hair follicles, nerves, sebaceous (oil) glands, and sudoriferous (sweat) glands c. tension lines (lines of cleavage)
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  • Fall '15
  • stephaniemartinez
  • Anatomy

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