Dr. Rod, Human Anatomy & Physiology, Skin What is it? (Anatomy) What is it? (Anatomy) What does it do? (Physiology) What does it do? (Physiology)

Learning Objectives At the end of the lesson, students will be able to: 1. Describe the functions of the integumentary system. 2- Identify the major structures found in the layers of the skin. 3. Describe the anatomy and physiology of hair and nails 4. Compare and contrast 1 st, 2 nd, & 3 rd degree burns 5. Discuss the significance of the ABCD rule Dr. Rod, Human Anatomy & Physiology, Skin

What is it (anatomy)? Outer covering of bodyOuter covering of body Epidermis (thinner outer layer of skin)Epidermis (thinner outer layer of skin) Dermis (thicker connective tissue layer)Dermis (thicker connective tissue layer) Hypodermis (subcutaneous layerHypodermis (subcutaneous layer Largest organ of the body (15% of body weight). Covers 1.5 – 2 square meters

Components Integumentary System Includes:Integumentary System Includes: Skin (cutaneous membrane) Subcutaneous tissue below the skin Accessory Structures: Sweat glands Sebaceous or oil glands HairNails Dr. Rod, Human Anatomy & Physiology, Skin

Functions of the Integumentary System Protection –First line of defense against Bacteria Viruses –Protects underlying structures from Ultraviolet (UV) radiation Dehydration

Functions of the Integumentary System (cont.) Body temperature regulation –If too hot Dermal blood vessels dilate Vessels carry more blood to surface so heat can escape –If too cold Dermal blood vessels constrict Prevents heat from escaping

Vitamin D production –Needed for calcium absorption Sensation –Sensory receptors Excretion –Small amounts of waste products are lost through perspiration Functions of the Integumentary System (cont.)

Dr. Rod, Human Anatomy & Physiology, Skin What is it made of? (histology—study of tissues) Layers of skin are two fundamental types of tissue organizationLayers of skin are two fundamental types of tissue organization –Epidermis = epithelium –Dermis = connective tissue

10 Layers of the Epidermis: The epidermis is a stratified epithelium. It is avascular. Stratum corneum Stratum lucidum Stratum granulosum Stratum spinosum stratum basale

Dr. Rod, Human Anatomy & Physiology, Skin Epidermis—a stratified epithelium

Dr. Rod, Human Anatomy & Physiology, Skin Cells in the Epidermis 1- Keratinocytes: most abundant produce keratin (fibrous protein) protective; waterproofing the skin

Dr. Rod, Human Anatomy & Physiology, Skin Cells in the Epidermis 2- Melanocytes: - cells produce brownish/black pigment called melanin. (8% of epidermal cells) - lack of melanin: albino

Dr. Rod, Human Anatomy & Physiology, Skin Dermis—connective tissue substrate

What are the Characteristics of the Dermis? Made up of connective tissue The protein collagen makes the dermis tough and leatherlike Richly supplied with blood vessels and lymph vessels Has hair follicles, oil and sweat glands and sensory receptors Ridges formed from the papillary layer can form finger prints.

What are the major appendages of the Skin? Sweat glands Sebaceous glands Hairs Nails

What are the types of glands found in the skin? Sweat glands-sudoriferous Sebaceous glands- oil glands (sebum) –Softens and lubricates hair and skin –Slows water loss and kills bacteria

What are hairs? Made from hair follicles Made of dead keratinized skin cells Two parts: shaft and root Roughly 1mm every 3 days

Why is hair useful? Senses insects that land on the skin. Hair on the head protects the head from a blow, sunlight and heat loss. Eyelashes shield the eye Nose hairs filter the air

What are the parts of nails? A nail is a scalelike modification of the epidermis Made of tightly compressed keratinized cells Useful tools to pick up small objects or scratch an itch. Nail matrix is the region responsible for nail growth. A nail is a scalelike modification of the epidermis Made of tightly compressed keratinized cells Useful tools to pick up small objects or scratch an itch. Nail matrix is the region responsible for nail growth.

What are the 3 types of burns? First-degree burns: only the epidermis is damaged. Redness, swelling and pain are common. (sunburn) 2-3 days to heal Second-degree burns: epidermis and upper layers of dermis. Blistering can occur. 3-4 weeks to heal. Third-degree burns: involves the entire thickness of the skin.

Burns –First degree burn: involves epidermis only  redness (erythema) – sun burn - painful - no scarring

Burns –Second degree burn

Burns –Third degree burn: involves epidermis and entire dermis (and sometimes more) –Not painful! Why?

Melanoma –Cancer of melanocytes (very dangerous) –5% of skin cancers but rising fast –Can arise from preexisting moles –Appears as a spreading brown or black patch –Chance of survival is poor if the lesion is greater than 4 mm thick

Melanomas Usually, starts from a mole Watch for changes in shape, height or color of the mole Melanomas are one of the deadliest cancers

What is the ABCD rule? Used for recognizing melanoma A-Asymmetry: two sides of the pigmented mole do not match B-Border irregularity: borders are not smooth C- Color: lesion has a multiple of colors D- Diameter the spot is larger than 6 mm in diameter (size of a pencil eraser)

Dr. Rod, Human Anatomy & Physiology, Skin