The document summarizes the structure and function of the integumentary system in 3 paragraphs: The integumentary system has two main divisions - the skin and accessory structures. The skin is the largest organ and has two layers, the epidermis and dermis. Accessory structures include sweat and sebaceous glands, hair follicles, and nails, which are derived from the epidermis. The epidermis has several strata with different cell types and densities. The dermis lies below with two layers - a papillary layer interdigitated with the epidermis and a deeper reticular layer. Various sensory receptors are located within the skin layers. The skin has

1. Lecture 5 Integumentary System

3. Figure 5.1: Skin structure, p. 153. Epidermis Dermis Hypodermis (superficial fascia) Hair root Hair shaft Pore Dermal papillae (papillary layer of dermis) Meissner's corpuscle Free nerve ending Reticular layer of dermis Sebaceous (oil) gland Arrector pili muscle Sensory nerve fiber Eccrine sweat gland Pacinian corpuscle Artery Vein Adipose tissue Hair follicle receptor (root hair plexus) Hair follicle Eccrine sweat gland

5. Figure 5.2: The main structural features in skin epidermis, p. 154. Sensory nerve ending Melanocytes Melanin granules Merkel cell Langerhans’ cell Stratum corneum Stratum granulosum Stratum spinosum Stratum basale Dermis Dermis Cells are dead; represented only by flat membranous sacs filled with keratin. Glycolipids in extracellular space. Cells are flattened; organelles deteriorating; cytoplasm full of lamellated granules (release lipids) and keratohyaline granules. Cells contain thick bundles of intermediate filaments made of pre-keratin. Cells are actively mitotic stem cells; some newly formed cells become part of the more superficial layers. Keratinocytes Desmosomes (b) (a)

12. Figure 5.1: Skin structure, p. 153. Epidermis Dermis Hypodermis (superficial fascia) Hair root Hair shaft Pore Dermal papillae (papillary layer of dermis) Meissner's corpuscle Free nerve ending Reticular layer of dermis Sebaceous (oil) gland Arrector pili muscle Sensory nerve fiber Eccrine sweat gland Pacinian corpuscle Artery Vein Adipose tissue Hair follicle receptor (root hair plexus) Hair follicle Eccrine sweat gland

15. Accessory Structures of the Skin Sweat glands Sebaceous glands Hairs/hair follicles Nails

17. Figure 5.3: Cutaneous glands, p. 159. Sebaceous gland duct Sebaceous gland Sweat pore Eccrine g land (a) Sectioned sebaceous gland (b) Sectioned eccrine gland

22. Figure 5.3a

24. Figure 5.4 Hairs = Pili Produced by cells in the MATRIX inside hair follicles Each hair has 2 regions – shaft and root SHAFT – region exposed above the skin ROOT – region below the skin enclosed by the hair follicle

25. Hairs = Pili Produced by cells in the MATRIX inside hair follicles Each hair has 2 regions – the shaft and the root SHAFT – region exposed above the skin ROOT – region below the skin enclosed by the hair follicle Matrix

26. Figure 5.5c-d: Structure of a hair and hair follicle , p. 161. Hair shaft Arrector pili Sebaceous gland Hair root Hair bulb in follicle Hair root (cuticle, cortex, medulla) Internal epithelial root sheath External epithelial root sheath Connective tissue root sheath Hair matrix e Hair papilla Subcutaneous adipose tissue Medulla Cortex Glassy membrane (d) (c)

27. Figure 5.5a-b: Structure of a hair and hair follicle, p. 161. Hair shaft Arrector pili Sebaceous gland Hair root Hair bulb in follicle Connective tissue root sheath Follicle wall Cuticle Cortex Medulla Internal epithelial root sheath External epithelial root sheath Glassy membrane (a) (b) 2 regions – shaft and root SHAFT – region above the skin ROOT – region below the skin enclosed by the hair follicles

30. Figure 5.6: Structure of a nail , p. 163. Free edge of nail Body of nail Lateral nail fold Lunula Eponychium (cuticle) Nail matrix Root of nail Proximal nail fold Eponychium (cuticle) Body of nail Nail bed Free edge of nail Hyponychium Phalanx (bone of fingertip) (a) (b)

31. Figure 5.7 Basal cell carcinoma Squamous cell carcinoma Melanoma

33. Figure 5.8: Estimating the extent and severity of burns, p. 167. Totals Anterior and posterior head and neck, 9% Anterior and posterior upper limbs, 18% Anterior and posterior trunk, 36% Anterior and posterior lower limbs, 36% (Perineum, 1%) 100% 4 1 / 2 % Anterior trunk, 18% 9% 9% (a) (b) (c) (d) 4 1 / 2 % 4 1 / 2 % First-degree burn Second-degree burn Third-degree burn blisters

36. Figure UN 5.1