Integumentary System It’s Skin-tastic!! Fun Facts • Considered the body’s largest organ – 15-20 square feet. • Also considered an organ system General Functions 1. Protection • Mechanical • Chemical • Bacterial • UV • Desiccation 2. Temperature Homeostasis • Too hot: sweat glands, flushing • Too cold: arrector pilli, pale 3. Excretion • Sweat glands release water, salts, ammonia • Oil glands release lipids, acids 5. Sensation • Touch • Pressure • Heat • Cold • Pain 5. Synthesis • Light passes through skin to convert vitamin D into usable form 7. Non-Verbal Communication • Facial expressions Anatomy • Epidermis Skin • Dermis • Subcutaneous layer or hypodermis Layer #1 • Epidermis - Top Layer – Five layers – Top layer is keratinized (waxy) for protection and water proofing – Replaced every 35-45 days – Holds melanocytes, which are responsible for turning your skin colors Layer #2 • Dermis - Middle Layer – Mostly connective tissue for strength – Lots of blood vessels – Dermal papilla: makes finger prints – Sebaceous gland: produces oil – Arrector Pili: muscle makes hair stand up – Sweat gland: helps regulate temperature Layer #3 • Hypodermis - Bottom layer – Mostly fat – Good for insulation (not as much in babies/ elderly) – Attaches the dermis to the underlying organs – Contains LOTS of blood vessels Accessory organs or epidermal derivatives • Hairs – Epidermal growths that function in protection – Shaft, root, and folllicle – Sebaceous glands, arrector pili muscle, and hair root plexus (touch) – Hair growth and replacement have a cyclical pattern – ‘male-pattern’ baldness Nails • Plates of highly packed, keratinized cells • Protection, scratching, & manipulation • Formed by cells in nail bed called the matrix ( in area of lunula) • Grow 1 mm / week • Eponychium - cuticle • Hyponychium - little skin under nail Skin Glands • Sebaceous (oil) glands – Usually connected to hair follicles – Moistens hair and waterproofs skin • Sweat glands • Water, salt, wastes • Function is to cool the body (also nervous) • Odor occurs when broken down by bacteria • Ceruminous glands – Modified sweat glands – Secrete cerumen (ear wax) • Mammary glands – Secrete milk Skin color • Genetic factors – All races have the same number of melanocytes, but the types of pigments they have are different – Albinism • Environmental factors – Uv light or x-rays Skin Pigments Three pigments contribute to skin color: 1. Melanin: • Yellow to red to dark brown • Responsible for darker skin colors • Freckles and moles come from large accumulations of melanin Skin Pigments 2. Carotene: • Yellow to orange • Most obvious in the palms and soles of feet • Found in carrots Skin Pigments 3. Hemoglobin: • Reddish pigment • Responsible for the pinkish hue of the skin • Carried in blood .