Skin and the Integumentary System Chapter 6 Objectives: Identify anatomical structures and functions of the integumentary system. Identify accessory organs of the integumentary system. Recognize diseases and disorders of the integumentary system.

Integumentary System Def.: the skin and its accessory organs Skin is called the cutaneous membrane. Other membranes and their locations: Serous membranes – line cavities not open to the outside of the body Mucous membranes - ? Synovial membranes – form the inner linings of synovial joints (between freely movable bones) Mucous membranes line cavities and tubes that open to the outside of the body 2

2 Distinct Layers of the Skin Epidermis = ? Dermis = ? Separated by an undulating (???) basement membrane (???). Epidermis is made of stratified squamous epithelium (???). Dermis is thicker and contains collagenous (???) and elastic (???) fibers, epithelial tissue, smooth muscle tissue, nervous tissue, and blood(???). Subcutaneous layer (“hypodermis”) = ?; made up of loose connective and adipose tissue. Epidermis = upon skin (outer layer of the skin) “undulating” = moving in a wave-like pattern Basement membranes anchor epithelial tissue to underlying connective tissue. Label 1-3 of Diagram A 3

A. Epidermis Characteristics Cells Keratinocytes - outer cells fill with a tough, fibrous, waterproof keratin protein Melanocytes – produce melanin, providing dark pigmentation Layers (details on next slide) Growth (details on following slides) What purpose would keratinization serve for the epidermis? 4

2. Layers (top to bottom): Stratum corneum 25-30 layers of flat, dead, keratinocytes Continuously shed and replaced Stratum lucidum 3-5 layers of flat, dead keratinocytes Only present in thick skin of palms and soles Stratum granulosum 3-5 layers of flattened, dying keratinocytes Dividing line between living and dead layers Stratum spinosum 8-10 layers of keratinocytes Some can still undergo cell division Cells are tightly joined together Provides skin with strength and flexibility Stratum basale Stratum germinatum – where new cells are produced Single row of cuboidal or columnar keratinocytes Basement membrane Add these layers to Diagram A (4-6). 5

Growth process New cells form in the stratum _______________. Cells keratinize and die as they are push toward the surface. They eventually slough off at the surface. Total process ≅ 4 weeks germinatum 6

B. Dermis Contains: Collagen fibers (70%) – strength Elastic fibers – elasticity Capillaries Tactile (touch) receptors Hair follicles Nerve cell processes Sebaceous glands Sweat glands 7

B. Dermis Epidermal ridges project into the dermis + dermal papillae (conical projections of the dermis) passing into the spaces between the ridges cause the boundary between dermis and epidermis to be uneven (undulating). This undulation continues all the way to the outer layer, forming valleys and ridges known as fingerprints. Draw this on the board for students. Add labeling to Drawing A. Fingerprinting activity 8

Skin Color 3 Pigments: Melanin – dark Carotene – yellow-orange Hemoglobin – red (bright red) if well oxygenated Blue (dark red) if not What dark marks on the skin are caused by an accumulation of melanin? Discuss vitamin A problems, albinism, cyanosis, jaundice, erythema 9