5 C h a p t e r The Integumentary System PowerPoint® Lecture Slides prepared by Jason LaPres Lone Star College - North Harris Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The integumentary system consists of Cutaneous membrane Epidermis Dermis Accessory structures Subcutaneous layer

Integumentary system functions: Protection Excretion Temperature maintenance Nutrient storage Vitamin D3 synthesis Sensory detection

Figure 5.1 The Components of the Integumentary System

Figure 5.2 Thin Skin and Thick Skin The epidermis is composed of layers of keratinocytes Thin skin = four layers (strata) Thick skin = five layers Figure 5.2

The epidermis Provides mechanical protection Prevents fluid loss Keeps microorganisms from invading the body

Layers of the epidermis: Stratum germinativum Stratum spinosum Stratum granulosum Stratum lucidum Stratum corneum

Figure 5.3 The Epidermal Ridges of Thick Skin

Epidermal characteristics: Cells accumulate keratin and eventually are shed Epidermal ridges are interlocked with dermal papillae Fingerprints Improve gripping ability Langerhans cells (immunity) in s. spinosum Merkel cells (sensitivity) in s. germinativum

Figure 5.4 The Structure of the Epidermis

Skin color depends on Blood supply Carotene and melanin Melanocytes produce melanin and protect from UV radiation Epidermal pigmentation Interrupted blood supply leads to cyanosis

Figure 5.5 Melanocytes Figure 5.5a, b

Epidermal cells Synthesize vitamin D3 (cholecalciferol) when exposed to UV Respond to epidermal growth factor Growth Division Repair Secretion

Dermal Organization Papillary layer Contains blood vessels, lymphatics, sensory nerves of epidermis Reticular layer Contains network of collagen and elastic fibers to resist tension

Figure 5.7 Dermal Circulation

Stretch marks Caused by excessive stretching of the dermis Patterns of collagen and elastic fibers form lines of cleavage

Figure 5.6 Lines of Cleavage of the Skin

Dermal Circulation and innervation Cutaneous plexus arteries found in subcutaneous layer/papillary dermis Cutaneous sensory receptors (light touch, pressure)

Hypodermis Stabilizes skins position against underlying organs and tissues

Hairs Originate in hair follicle Composed of root and shaft Root base (hair papilla) surrounded by hair bulb and root hair plexus Hairs have soft medulla and hard cortex Cuticle = superficial dead protective layer

Figure 5.8 The Anatomy of a Single Hair

Hair types Vellus hairs (peach fuzz) Terminal hairs (heavy) Club hair (cessation of growth) Shed and grow according to hair growth cycle Arrector pili muscle attaches to hair

Figure 5.9 Hair Follicles Figure 5.9

Glands in the skin Sebaceous Suderiferous Mammary Ceruminous

Sebaceous glands Discharge waxy sebum onto hair shaft when associated with hairs Sebaceous follicles discharge onto epidermal surface

Figure 5.10 Sebaceous Glands and Follicles

Suderiferous glands Apocrine sweat glands Produce odorous secretion Merocrine (eccrine) sweat gland Sensible perspiration

Figure 5.11 Sweat Glands Figure 5.11a, b

Other glands Mammary glands Structurally similar to apocrine sweat glands Ceruminous glands In ear, produce waxy cerumen

Nails Nail body covers the nail bed Nail production occurs at the nail root Eponychium (cuticle) overlies root Free edge of nail extends over hyponychium

Figure 5.12 The Structure of a Nail

Injury and repair Regenerates easily Regeneration process includes formation of Scab Granulation tissue Scar tissue

Figure 5.13 Integumentary Repair Figure 5.13, step 1-2

Figure 5.13 Integumentary Repair Figure 5.13, step 3-4

You should now be familiar with: The components of the integumentary system, including their physical relationships. The functions of the integumentary system. The main features and functions of the epidermis and dermis. Individual and racial differences in skin. The effects of UV light on the epidermis. The structure and function of the various accessory organs of the skin. How the skin responds to repair.