INTEGUMENTARY SYSTEM.pptx #organsystems

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1. INTEGUMENTARY SYSTEM

2. INTEGUMENTARY SYSTEM Definition: The Integumentary System is the body’s outer protective covering and is the largest organ system of the human body. It mainly consists of the skin, along with its accessory structures such as hair, nails, sweat glands, and sebaceous (oil) glands.

3. INTEGUMENTARY SYSTEM Importance &functions: It is the largest organ system (skin covers about 1.5–2 m² in adults). Serves as the first line of defense against injury, infection, and harmful environmental factors. Essential for homeostasis – maintaining stable internal conditions. Plays a vital role in temperature regulation and fluid balance. Helps in Vitamin D synthesis, which is important for calcium metabolism and bone health. Provides sensory input about the external environment (touch, pain, temperature).

4. INTEGUMENTARY SYSTEM Functions: Protection Acts as a barrier against pathogens, UV radiation, and physical injury. Prevents dehydration by reducing water loss. Regulation of Body Temperature Sweat secretion and evaporation cool the body. Blood vessels dilate or constrict to maintain heat balance. Sensation Contains sensory receptors for touch, pain, pressure, and temperature. Excretion Sweat glands eliminate small amounts of waste (salts, urea, water). Vitamin D Synthesis Skin cells produce Vitamin D when exposed to sunlight, needed for bone growth and calcium absorption. Storage Stores lipids and water in dermis and hypodermis. Immunity Provides defense through specialized cells (Langerhans cells in epidermis). Homeostasis: By performing these protective and regulatory functions, the integumentary system helps maintain a stable internal environment necessary for cell and organ function. 

5. INTEGUMENTARY SYSTEM 🔹 Main Components Skin Epidermis – outermost layer; made of stratified squamous epithelium; provides barrier and protection. Dermis – deeper connective tissue layer; contains blood vessels, nerves, hair follicles, sweat & sebaceous glands. Hypodermis (subcutaneous tissue) – fat layer beneath dermis; provides insulation and cushioning. Hair – provides protection, helps with sensation, reduces heat loss. Nails – protect fingertips and toes, aid in fine motor functions. Glands Sweat glands ( sudoriferous glands) – regulate temperature via perspiration. Sebaceous glands – secrete sebum (oil) to lubricate skin and hair. Ceruminous glands – produce earwax in the ear canal.

6. Layers of skin

7. Layers of skin LAYERS OF THE SKIN : The skin is composed of three primary layers, each with specialized cells and structures:  Epidermis:  The outermost, protective layer that is avascular (lacks a blood supply). It consists of several sub-layers (strata) made mainly of keratinocytes. In thick skin (soles and palms), there is an extra layer called the stratum lucidum . The epidermis also contains: Keratinocytes: Produce the tough protein keratin and form a waterproof barrier. Melanocytes: Produce the pigment melanin, which determines skin color and protects against UV radiation. Langerhans cells: Immune cells that help fight off infections. Merkel cells: Act as mechanoreceptors for light touch.

8. Layers of skin

9. Layers of skin Dermis:  A thicker, middle layer of connective tissue that supports the epidermis. It is rich in blood vessels, nerves, and sensory receptors. The dermis has two sub-layers: Papillary layer: Contains dermal papillae (finger-like projections) that interlock with the epidermis. It houses nerve endings for touch and capillary loops that supply the epidermis with nutrients. Reticular layer: Composed of dense connective tissue with collagen and elastin fibers, which provide the skin with strength and elasticity. Hypodermis:  The deepest, subcutaneous layer of the skin, composed of loose connective and adipose (fat) tissue. It serves to insulate and cushion the body, connects the skin to underlying muscles, and stores energy. .

10. Layers of skin

11. Accessory structures Hair:  Keratinous filaments that originate from hair follicles in the dermis. The arrector pili muscles attach to hair follicles and contract to cause " goosebumps ". Nails:  Layers of hardened, keratin-filled cells that cover and protect the tips of fingers and toes. Glands: Sudoriferous (sweat) glands :  Eccrine glands are found all over the body for thermoregulation, while apocrine glands are in the armpits and genital areas and produce milky, odor-causing sweat. Sebaceous (oil) glands : Secrete an oily substance called sebum to lubricate and waterproof the skin and hair. Ceruminous glands:  Modified sweat glands in the ear canal that produce earwax. 

12. Structure Definition Location Growth Functions Hair Thread-like keratinized outgrowths from hair follicles. Found on most of the body (except palms, soles, lips, parts of genitals). - Grows from hair follicle in the dermis. - Growth cycle: Anagen (growth), Catagen (transition), Telogen (resting). - Protects scalp from UV & injury. - Eyelashes/eyebrows protect eyes. - Nose/ear hair filters particles. - Provides sensation. Nails Hard plates of tightly packed keratinized cells. Tips of fingers and toes. - Produced by nail matrix at the base (under cuticle). - Growth = ~0.1 mm/day in fingers. - Protects fingertips & toes. - Enhances grip & precision. - Used for scratching & defense. Sebaceous (oil) glands Exocrine glands that secrete sebum (oil). Found in dermis, connected to hair follicles (absent in palms/soles). - Secretion increases at puberty due to hormones. - Lubricates skin & hair. - Prevents dryness & cracking. - Has antibacterial properties. Sweat (sudoriferous) glands Exocrine glands that secrete sweat. Two types: Eccrine & Apocrine. - Eccrine: widely distributed (palms, soles, forehead). - Apocrine: armpits, groin, around nipples. - Eccrine active from birth. - Apocrine become active at puberty. - Eccrine: Thermoregulation (cooling by evaporation). - Apocrine: Scent glands (pheromones), emotional sweating. Ceruminous glands Modified sweat glands that produce earwax (cerumen). External ear canal. - Active from early life, continuously secrete cerumen. - Protect ear canal by trapping dust & microbes. - Lubricates eardrum. Mammary glands Modified sweat glands that produce milk. Breasts (female). - Develop during puberty, functional during pregnancy/lactation. - Provide nutrition & immunity to infants.

13. INTEGUMENTARY SYSTEM Functions Function Description Importance / Significance Protection Acts as a barrier against mechanical injury, UV radiation, chemicals, and microorganisms. Prevents infections, physical damage, and harmful radiation effects. Temperature Regulation Sweat glands release sweat; blood vessels dilate (heat loss) or constrict (heat retention). Maintains homeostasis of body temperature. Sensation Contains receptors for touch, pressure, pain, vibration, and temperature. Helps in interaction with environment and protects from harmful stimuli. Excretion Sweat glands excrete small amounts of salts, urea, ammonia, and water. Aids in waste elimination and fluid balance. Vitamin D Synthesis UV light converts 7-dehydrocholesterol → Vitamin D₃ in skin. Essential for calcium & phosphate metabolism → bone health. Water Balance Prevents excessive water loss (keratin + lipid barrier). Maintains hydration and electrolyte balance. Storage Stores fat (energy), water, and some vitamins in hypodermis. Provides insulation, cushioning, and energy reserve. Immune Defense Langerhans cells and other immune components detect and fight pathogens. First line of defense in immune system. Aesthetic & Communication Skin color, hair, and nails contribute to appearance and expression. Important in social interaction & identity.

14. INTEGUMENTARY SYSTEM Physiology of the integumentary system Protection and immunity The integumentary system is the body's first line of defense, providing a physical, chemical, and biological barrier against the external world.  Physical barrier:  The tightly knit network of cells in the epidermis prevents the entry of pathogens, chemicals, and mechanical damage. UV radiation protection : Melanin absorbs UV radiation, protecting the skin and underlying structures from damage. Immune function : Langerhans cells and other immune cells patrol the skin, acting as the first line of defense against pathogens. Waterproof barrier : The keratin and lipids in the epidermis prevent excessive water loss from the body. 

15. Thermoregulation: The skin helps regulate body temperature to maintain homeostasis.  Heat loss: When the body is too warm, dermal blood vessels dilate ( vasodilation ) to increase blood flow to the skin, allowing heat to dissipate through radiation and convection. Sweat glands also release sweat, which cools the body as it evaporates. Heat conservation: When the body is too cold, dermal blood vessels constrict (vasoconstriction) to reduce blood flow to the skin, conserving heat in the body's core. The layer of fat in the hypodermis also provides insulation INTEGUMENTARY SYSTEM

16. Sensation: The skin contains various sensory receptors that allow the body to perceive and respond to external stimuli.  Touch: Merkel's disks and Meissner's corpuscles detect light touch, while Pacinian corpuscles detect deep pressure and vibration. Temperature:  Thermoreceptors detect changes in temperature. Pain:  Nociceptors are free nerve endings that respond to painful stimuli.  INTEGUMENTARY SYSTEM

17. Vitamin D synthesis: The skin plays a vital role in synthesizing vitamin D, which is essential for bone health.  When the skin is exposed to ultraviolet B (UVB) radiation from sunlight, a cholesterol-based steroid is converted into vitamin D3. This vitamin D3 is then processed by the liver and kidneys into its active form, which is necessary for the absorption of calcium and phosphorus. INTEGUMENTARY SYSTEM

18. INTEGUMENTARY SYSTEM Physiological Process Description Functions / Significance Keratinization Process by which keratinocytes form in the stratum basale, move upward, fill with keratin, die, and form the stratum corneum. Produces a tough, waterproof barrier that protects against mechanical injury, microbes, and dehydration. Melanin Production (Pigmentation) Melanocytes in the stratum basale produce melanin, which is transferred to keratinocytes. Provides skin color and protects DNA from UV radiation damage. Sweating (Perspiration) Sweat glands (eccrine & apocrine) secrete sweat onto the skin surface. Regulates body temperature and excretes small amounts of waste (salts, urea). Thermoregulation (Vasodilation & Vasoconstriction) Blood vessels in dermis dilate (release heat) or constrict (conserve heat). Maintains stable internal body temperature (homeostasis). Vitamin D Synthesis UV rays convert 7-dehydrocholesterol in skin → Vitamin D₃ (cholecalciferol). Helps in calcium & phosphate absorption for bone health. Wound Healing Process of skin repair after injury: inflammation → proliferation → remodeling. Restores integrity of skin barrier and prevents infection. Sensation Sensory receptors (Merkel cells, free nerve endings, Meissner’s corpuscles, Pacinian corpuscles) detect stimuli. Provides awareness of touch, pressure, temperature, vibration, pain. Sebum Secretion Sebaceous glands secrete sebum (oil). Lubricates skin & hair, prevents dryness, has antibacterial properties. Immune Defense Langerhans cells capture antigens and activate immune response. Protects against microbes and harmful foreign substances.

19. INTEGUMENTARY SYSTEM 🔹 Common Disorders Acne – inflammation of sebaceous glands. Eczema – allergic/inflammatory skin condition. Psoriasis – autoimmune disorder causing rapid skin cell buildup. Skin cancer – includes basal cell carcinoma, squamous cell carcinoma, melanoma. Infections – fungal (ringworm), bacterial (impetigo), viral (herpes).

20. Disorder Definition Location Importance / Complications How it Attacks (Pathophysiology) Acne vulgaris Inflammatory disorder of sebaceous glands & hair follicles. Common on face, chest, back (areas with many sebaceous glands). Cosmetic concern, may lead to scarring, infection. Excess sebum + clogged follicle + bacterial growth (Propionibacterium acnes) → inflammation. Eczema (Atopic Dermatitis) Chronic inflammatory skin condition. Usually on hands, elbows, knees, face. Causes itching, dryness, thickened skin, risk of infection. Immune system hypersensitivity + barrier defect → inflammation & itching. Psoriasis Autoimmune disease with rapid turnover of epidermal cells. Elbows, knees, scalp, lower back. Thick, scaly patches; may cause arthritis (psoriatic arthritis). T-cell mediated autoimmune reaction → keratinocyte overgrowth. Skin Infections Microbial invasion of skin layers. Can occur anywhere. Can spread systemically if untreated. - Bacterial: Impetigo (Staphylococcus/Streptococcus). - Fungal: Ringworm, Athlete’s foot. - Viral: Herpes, Warts. Burns Tissue damage from heat, chemicals, electricity, radiation. Any exposed body part. Leads to fluid loss, infection, scarring. Destroys skin layers: - 1st°: epidermis only - 2nd°: epidermis + dermis - 3rd°: all layers. Skin Cancer Abnormal, uncontrolled growth of skin cells. Common in sun-exposed areas (face, neck, arms). Life-threatening if metastatic; most common cancer. - Basal cell carcinoma: from stratum basale. - Squamous cell carcinoma: from keratinocytes. - Melanoma: from melanocytes, highly aggressive. Vitiligo Autoimmune loss of melanocytes causing depigmentation. Patchy areas on skin, especially exposed parts. Cosmetic concern, ↑ UV damage risk. Autoimmune destruction of melanocytes → loss of melanin. Alopecia Hair loss from scalp or body. Scalp (most common), but can affect entire body. Psychological impact; sometimes permanent. Autoimmune attack on hair follicles or hormonal imbalance. Clinical Aspects / Disorders of the Integumentary System

21. Aging & Integumentary System Change with Aging Description Effects / Importance Significance / Consequences Thinning of epidermis & dermis Epidermal cell turnover slows, dermis loses collagen & elastin. Skin becomes fragile & less elastic. Increased risk of tears, wrinkles, sagging. Reduced melanocyte activity Fewer melanocytes in stratum basale. Skin appears pale, hair turns gray/white. Less UV protection → higher skin cancer risk. Decreased Langerhans cells Lower immune cell numbers in skin. Reduced immune defense. Higher risk of infections & delayed healing. Reduced gland activity Sweat & sebaceous glands become less active. Dry, itchy skin; less effective thermoregulation. Higher risk of dehydration, heat stroke. Loss of subcutaneous fat (hypodermis) Fat layer thins under skin. Less cushioning & insulation. Greater susceptibility to injury & feeling cold. Slower wound healing Cell division & repair processes slow down. Cuts & abrasions take longer to heal. Higher risk of chronic wounds & infections. Hair changes Hair follicles shrink; melanocyte activity stops. Hair thins, turns gray/white, slower growth. Cosmetic & psychological effects. Nail changes Nails grow slower, may become brittle or thick. Reduced protection of fingertips & toes. Higher risk of fungal infections & injury. Formation of age spots Localized increase in melanocyte activity in sun-exposed areas. Brown spots appear on skin. Cosmetic concern; may resemble melanoma (needs monitoring).

22. Integumentary System – Summary / Review Main Important Points Definition – The integumentary system = skin + accessory structures (hair, nails, glands). Skin Layers – Epidermis (strata: basale, spinosum, granulosum, lucidum, corneum). Dermis (papillary + reticular). Hypodermis (fat & connective tissue). Cells of Epidermis – Keratinocytes, Melanocytes, Langerhans cells, Merkel cells. Accessory Structures – Hair, Nails, Sebaceous glands, Sweat glands, Ceruminous glands, Mammary glands. Functions – Protection, Temperature regulation, Sensation, Excretion, Vitamin D synthesis, Water balance, Storage, Immunity, Aesthetics. Physiology – Keratinization , Melanin production, Sweating, Vasodilation /Constriction, Vitamin D synthesis, Wound healing, Sensory reception, Sebum secretion, Immune defense. Clinical Aspects – Acne, Eczema, Psoriasis, Infections, Burns, Skin cancers, Vitiligo , Alopecia. Aging – Thinner skin, wrinkles, gray hair, dry skin, slower healing, less immune defense.

23. Summary (Short Form for Exam) Largest organ system (~16% body weight). Skin layers: Epidermis → Dermis → Hypodermis. Major cells: Keratinocytes, Melanocytes, Langerhans, Merkel. Key functions: Protection, regulation, sensation, vitamin D, excretion. Disorders: Acne, psoriasis, burns, skin cancers. Aging: Wrinkles, thinning, dryness, reduced healing.

24. Review Questions (For Practice) Short Answer Define the integumentary system. Name the layers of the epidermis (deep to superficial). Write functions of keratinocytes, melanocytes , Langerhans, and Merkel cells. List accessory structures of the skin. Mention any 5 functions of the integumentary system. Long Answer Describe the anatomy of the skin with labeled diagram. Explain the physiology of thermoregulation in skin. Discuss the clinical aspects/disorders of the integumentary system. Write a note on aging changes in skin. Explain wound healing process in the skin.