Skin and the Integumentary System Section 32:1

The Structure of the Skin Skin is a multilayered organ that covers and protects the body Largest system of body – 16% of body weight Copyright © McGraw-Hill Education The Integumentary System

The Structure of the Skin The epidermis The outer superficial layer of skin is the epidermis. The outer layers of epidermal cells contain keratin, which waterproofs and protects the cells and tissues that lie underneath. Copyright © McGraw-Hill Education The Integumentary System

The Structure of the Skin The epidermis Some cells in the inner layer of the epidermis provide protection from harmful ultraviolet radiation by making a pigment called melanin. Copyright © McGraw-Hill Education The Integumentary System

The Structure of the Skin The dermis Directly beneath the epidermis. The dermis consists of connective tissue, nerve cells, muscle fibers, sweat glands, oil glands, and hair follicles. Below the dermis layer is the subcutaneous layer a layer of connective tissue stores fat & helps the body retain heat. Copyright © McGraw-Hill Education The Integumentary System

The Structure of the Skin Hair and nails Both hair and nails contain keratin and develop from epithelial cells. Hair cells grow out of narrow cavities in the dermis called hair follicles. Hair follicles usually have sebaceous glands associated with them that lubricate the skin and hair. Copyright © McGraw-Hill Education The Integumentary System

Functions of the Integumentary System Vitamin production Produces Vitamin D Increases the absorption of calcium Protection First line of defense Keeps skin from drying out Copyright © McGraw-Hill Education The Integumentary System

Functions of the Integumentary System Temperature regulation Blood vessels in skin expand and contract depending on temperature Cold  blood vessels narrow Keep warm blood away from surface Hot  blood vessels expand Bring warm blood to surface Copyright © McGraw-Hill Education The Integumentary System

Functions of the Integumentary System Sensation and senses Send signals through the spinal cord to the brain Nerve receptors are not evenly spaced throughout the body Furthest apart: middle of back Closest together: hands, lips, face, tongue and feet Increases the absorption of calcium Copyright © McGraw-Hill Education The Integumentary System

Ridges and Ducts Figure 5–4

Functions of the Integumentary System Health Warnings texture temperature color Yellowish color - Liver Dark brown spots - cancer Copyright © McGraw-Hill Education The Integumentary System

Protection and Care of Skin Sunlight UVB rays cause sunburns Sunscreen spf 15+ Protects against 93% UVB rays Prevent sunburn, wrinkles and skin cancer UVA rays cause wrinkling and sunspots Penetrate deeper Both types of rays can lead to cancer Copyright © McGraw-Hill Education The Integumentary System

Protection and Care of Skin Cuts Gently wash cut with warm water and soap Apply antibiotic Cover until healed shut 1-2 days Copyright © McGraw-Hill Education The Integumentary System

Protection and Care of Skin Burns Classified by severity Apply a burn cream Silvadine Copyright © McGraw-Hill Education The Integumentary System

Degrees of Burn Injuries Partial-thickness burns Full-thickness burns (a) First degree (b) Second degree (c) Third degree

Rule Of Nines 6-17

The Skin Gun National Geographic

Protection and Care of Skin Insect Bites & Rashes Avoid scratching Use ointment to reduce itching Lotions may have a burning sensation Copyright © McGraw-Hill Education The Integumentary System

Protection and Care of Skin Washing Use warm water and mild soap Strong soaps may remove oil from skin Moisturizers help skin stay moist Apply lotion after shower/bath Skin sill be Softer Smoother More elastic Copyright © McGraw-Hill Education The Integumentary System

Life Span Changes Scaly Skin Age Spots Dermis Becomes Reduced Loss of Fat Wrinkles Sagging Sebaceous Glands Secrete Less Oil Melanin Production Slows Hair Thins Number of Hair Follicles Decrease Impaired Nail Growth Sensory Receptors Decline Inability to Control Body Temperature Less Vitamin D Production 6-18

Clinical Application Acne Vulgaris 6-19 Most Common Skin Disorder Sebum And Epithelial Cells Clog Glands Produces Whiteheads And Blackheads (Comedones) Anaerobic Bacteria Trigger Inflammation (Pimple) Largely Hormonally Induced Androgens Stimulate Sebum Production Treatments Include Antibiotics, Topical Creams, Birth Control Pills 6-19

Lines of Cleavage Collagen and elastic fibers in the dermis: are arranged in parallel bundles resist force in a specific direction

Clinical Importance Lines of cleavage establish important patterns: a parallel cut remains shut, heals well a cut across (right angle) pulls open and scars

Lines of Cleavage Figure 5–7