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