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Understanding the Integumentary System: Structure and Function of Skin and Accessories

This chapter delves into the integumentary system, highlighting the skin's structure, protective functions, and accessory components. It covers the skin's layers—the epidermis and dermis—and their roles in sensation, protection, thermoregulation, and secretion. Key features include the process of keratinization, the function of hair and nails, as well as glands that produce sebum and sweat. The chapter also discusses how these elements work together to maintain health and respond to environmental changes, providing insights into the complex biology of the skin.

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Understanding the Integumentary System: Structure and Function of Skin and Accessories

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Presentation Transcript

  1. Chapter 6 The Integumentary System

  2. Introduction • Skin • Large waterproof covering • UV light and chemical protection • Accessory structures • Hair, nails, glands

  3. The Layers of the Skin

  4. Introduction • Epidermis: upper layer • Epithelial tissue divided into sublayers • Dermis: lower layer • Dense connective tissue • Connects skin to fat and muscle • Below dermis is subcutaneous layer called hypodermis

  5. Introduction (cont’d.)

  6. The Epidermis • Stratified, squamous, keratinized, epithelium • Keratinization • Cells move to surface, lose water and nuclei change • Composed of five layers

  7. The Epidermis (cont’d.) • Stratum corneum • Outermost layer • Dead, keratinized cells • Barrier to light, heat, chemicals, microorganisms

  8. The Epidermis (cont’d.) • Stratum lucidum • One to two cell layers thick • Flat and transparent • Difficult to see

  9. The Epidermis (cont’d.) • Stratum granulosum • Two or three layers • Flattened cells • Active keratinization • Lose nuclei • Compact and brittle

  10. The Epidermis (cont’d.) • Stratum spinosum • Several layers of spiny-shaped cells • Desmosomes prevalent • Desmosomes: interlocking cellular bridges

  11. The Epidermis (cont’d.) • Stratum germinativum • Rests on basement membrane • Lowermost layer called stratum basale • New cells produced here (mitosis) • Melanocytes: produce melanin • Skin color • Albinism

  12. The Dermis • Also called corium • Structures found in dermis • Blood and lymph vessels • Nerves • Muscles • Glands • Hair follicles

  13. The Dermis (cont’d.) • Divisions • Papillary • Adjacent to the epidermis • Reticular • Between papillary and subcutaneous • Subcutaneous (hypodermis) • Layers of fat below the dermis

  14. The Accessory Structures of the Skin

  15. Hair • Covers most of the surface of the body • Three parts: cuticle, cortex, medulla • Shaft: visible portion • Root: hair follicle • Arrector pili: smooth muscle

  16. Hair (cont’d.) • Growth • Hair follicle • Cycles of growth and rest • Texture: straight, curly, or tightly curly • Color: based on complex genetic factors

  17. Nails • Modified epidermal cells • Lunula: white crescent • Body: visible portion • Root: covered by skin • Growth occurs from the nailbed

  18. Nails (cont’d.)

  19. Sebaceous Glands • Produce sebum (oil) • Lubricates skin and hair • Secretion controlled by endocrine system • Increases at puberty • Decreases in later life

  20. Sweat Glands • Most numerous in palms and soles • Not found on margins of the lips or head of the penis • Each gland has secretory portion and excretory duct • Sweating helps cool the body

  21. Functions of the Integumentary System

  22. Sensation • Temperature receptors • Hot and cold • Pressure receptors • Excessive pressure as pain • Mild pressure as pleasurable • Combinations produce burning, itching, tickling

  23. Protection • Prevents passage of harmful physical and chemical agents • Melanin protects from UV rays • Lipid content inhibits water loss • Acid mantle: kills most bacteria • Nails protect ends of our digits • Hair acts as insulation and filter

  24. Thermoregulation • Normal body temperature: 98.6 degrees F • When external temperatures increase • Blood vessels dilate • Sweat occurs • When external temperatures decrease • Blood vessels first dilate then constrict

  25. Secretion • Sebum • Cosmetic gloss • Moisturizer • Antifungal/antibacterial properties • Sweat • Essential in cooling process • Vitamin D

  26. Animation – The Skin • Watch the Skin animation and see the structures of the skin up close. • [Insert The Skin.swf]

  27. Animation – Tissue Repair Watch the Tissue Repair animation to understand how the skin heals and a scar is formed after a deep laceration. [Insert tissue repair.swf]

  28. Summary • Discussed the layers of the epidermis and the process of keratinization • Described the structure of the dermis • Discussed the accessory structures of the skin including the hair and nails • Discussed the different functions of the integumentary system

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