Study Guide Module 2 MODULE 2 STUDY GUIDE The Integumentary System ⸻ CHAPTER 1: OVERVIEW OF THE INTEGUMENTARY SYSTEM Components of the Integumentary System The integumentary system consists of: * Skin * Hair * Nails * Sweat glands * Sebaceous glands The skin is the largest organ in the body. Functions of the Integumentary System 1. Protection 2. Sensation 3. Thermoregulation 4. Vitamin D synthesis 5. Communication ⸻ CHAPTER 2: LAYERS OF THE SKIN The skin has two major layers: Epidermis * Superficial layer * Keratinized stratified squamous epithelium * Avascular Dermis * Deeper layer * Connective tissue * Contains blood vessels, nerves, glands, and hair follicles Hypodermis * Not technically part of the skin * Also called subcutaneous layer * Contains adipose tissue Functions: * Energy storage * Cushioning * Insulation * Anchoring skin ⸻ CHAPTER 3: EPIDERMIS Cell Types Keratinocytes * Most abundant cells * Produce keratin Melanocytes * Produce melanin * Protect against UV radiation Tactile (Merkel) Cells * Touch receptors Dendritic Cells * Immune defense * Phagocytize pathogens ⸻ EPIDERMAL LAYERS Deep → Superficial Stratum Basale * Deepest layer * Single layer of cuboidal cells * Contains stem cells * Contains melanocytes * Contains tactile cells * Site of mitosis Stratum Spinosum * 8–10 layers thick * Contains dendritic cells * Connected by desmosomes Stratum Granulosum * 3–5 layers * Keratinization begins * Cells flatten * Organelles begin breaking down Stratum Lucidum * Only in thick skin * Palms and soles * Dead transparent cells Stratum Corneum * 15–30 layers * Dead keratinized cells * Protection from abrasion * Prevents dehydration ⸻ THICK VS THIN SKIN Thick Skin Found on: * Palms * Soles Contains: * Stratum lucidum Thin Skin Found everywhere else Does not contain: * Stratum lucidum ⸻ EPIDERMAL WATER BARRIER Located between: * Stratum spinosum * Stratum granulosum Functions: * Waterproofing * Prevents dehydration * Prevents excess water entry Components: 1. Filaggrin 2. Lamellar proteins 3. Lamellar lipids 4. Tight junction proteins ⸻ CHAPTER 4: DERMIS Made of connective tissue. Papillary Layer Contains: * Areolar connective tissue * Dermal papillae * Capillaries * Tactile corpuscles (Meissner corpuscles) Function: * Light touch sensation Reticular Layer Contains: * Dense irregular connective tissue * Hair follicles * Sweat glands * Sebaceous glands * Arrector pili muscles * Lamellated (Pacinian) corpuscles Function: * Deep pressure * Vibration sensation ⸻ DERMAL FIBERS Collagen Provides: * Strength * Support * Water retention Elastin Provides: * Elasticity * Stretching ability ⸻ CHAPTER 5: PIGMENTATION Melanin Produced by: * Melanocytes Functions: * Skin color * UV protection Effects of UV Exposure UV stimulates: * Keratinocytes * Melanocytes Result: * Increased melanin production * Tanning ⸻ Disorders of Pigmentation Albinism Cause: * Lack of melanin production Effects: * Pale skin * Light sensitivity * Increased skin cancer risk Vitiligo Cause: * Loss of melanocyte activity Effects: * White patches on skin ⸻ CHAPTER 6: FUNCTIONS OF THE SKIN Protection Protects against: * Microorganisms * Chemicals * UV radiation * Water loss * Physical trauma Dermicidin: * Antimicrobial substance in sweat ⸻ Sensory Function Skin detects: * Touch * Pain * Temperature * Pressure * Vibration Receptors Meissner Corpuscles * Light touch Pacinian Corpuscles * Deep pressure * Vibration Tactile Cells * Touch Hair Root Plexus * Detects hair movement ⸻ Thermoregulation When Body Is Hot Blood vessels: * Dilate Sweat glands: * Increase secretion Result: * Cooling When Body Is Cold Blood vessels: * Constrict Result: * Conserves heat Can lead to: * Frostbite ⸻ Vitamin D Synthesis UV exposure stimulates vitamin D production. Vitamin D helps: * Calcium absorption * Bone health * Immune function Deficiency causes: Rickets Children Osteomalacia Adults ⸻ Communication Examples: * Facial expressions * Goosebumps * Sweating * Hair patterns ⸻ CHAPTER 7: HAIR Hair Structure Hair Shaft Visible portion Hair Root Embedded portion Hair Follicle Surrounds root Hair Bulb Growth region Hair Matrix Mitotic cells Hair Papilla Blood supply ⸻ Hair Layers 1. Medulla 2. Cortex 3. Cuticle ⸻ Hair Functions * Protection * Thermoregulation * Sensation * Communication ⸻ Hair Growth Average: * 0.3 mm/day Normal loss: * About 50 hairs/day ⸻ Hair Color Determined by: * Melanin Gray hair: * Reduced melanin production ⸻ Arrector Pili Muscle Functions: * Causes goosebumps * Helps retain heat Controlled by: * Sympathetic nervous system ⸻ Alopecia Definition: * Hair loss Pattern baldness: * Hormonal and genetic ⸻ CHAPTER 8: NAILS Functions: * Protection * Support for grasping Structures: * Nail body * Nail root * Nail matrix * Nail bed * Lunula * Cuticle (eponychium) * Hyponychium ⸻ CHAPTER 9: GLANDS Eccrine Sweat Glands Location: * Most of body Functions: * Thermoregulation Secrete: * Water * Salt * Waste products ⸻ Apocrine Sweat Glands Location: * Armpits * Genital regions Characteristics: * Empty into hair follicles * Produce odor after bacterial breakdown ⸻ Sebaceous Glands Produce: * Sebum Functions: * Lubricates skin * Waterproofs skin * Prevents drying * Antibacterial effects ⸻ CHAPTER 10: SKIN CANCER Basal Cell Carcinoma Origin: * Stratum basale Characteristics: * Most common * Least likely to metastasize ⸻ Squamous Cell Carcinoma Origin: * Stratum spinosum Characteristics: * More aggressive * Can metastasize ⸻ Melanoma Origin: * Melanocytes Characteristics: * Most deadly * Highly metastatic ABCDE Rule A = Asymmetry B = Border irregularity C = Color variation D = Diameter > 6 mm E = Evolving ⸻ CHAPTER 11: SKIN DISORDERS Eczema Symptoms: * Dry skin * Itching * Rash * Inflammation Treatment: * Moisturizers * Corticosteroids ⸻ Acne Cause: * Excess sebum * Keratin buildup * Bacterial infection Common locations: * Face * Chest * Back ⸻ CHAPTER 12: WOUND HEALING Steps: 1. Clot Formation Stops bleeding 2. Scab Formation 3. Fibroblast Activity Produces collagen 4. Capillary Growth 5. Epidermal Repair ⸻ CHAPTER 13: BURNS First-Degree Burn Damage: * Epidermis only Symptoms: * Redness * Pain ⸻ Second-Degree Burn Damage: * Epidermis + part of dermis Symptoms: * Blisters * Swelling * Pain ⸻ Third-Degree Burn Damage: * Epidermis * Dermis * Hypodermis Characteristics: * Nerve destruction * Often painless initially * Requires grafting ⸻ Rule of Nines Head and neck = 9% Each arm = 9% Each leg = 18% Trunk = 36% Genitalia = 1% ⸻ CHAPTER 14: SCARS Scar Tissue Produced by: * Fibroblasts Contains: * Collagen Lacks: * Hair follicles * Sweat glands * Sebaceous glands ⸻ Keloid Raised scar due to excessive collagen Atrophic Scar Sunken scar Examples: * Acne scars * Chickenpox scars ⸻ CHAPTER 15: PRESSURE AND FRICTION INJURIES Bedsores Cause: * Prolonged pressure Result: * Reduced blood flow * Tissue death ⸻ Stretch Marks Cause: * Rapid growth * Pregnancy * Weight gain ⸻ Calluses Cause: * Repeated friction Result: * Thickened epidermis ⸻ Corns Specialized calluses ⸻ Blisters Cause: * Friction Result: * Fluid accumulation between skin layers ⸻ CHAPTER 16: AGING AND THE INTEGUMENTARY SYSTEM Changes: Epidermis * Thinner * Slower cell division Dermis * Less collagen * Less elastin * Slower healing Hypodermis * Fat redistribution * Less cushioning Hair * Thinner * Grayer Nails * Slower growth * More brittle Glands * Less sweat * Less sebum Skin * Wrinkles * Sagging * Dryness ⸻ HIGH-YIELD EXAM FACTS Epidermal Layers Basale → Spinosum → Granulosum → Lucidum → Corneum Touch Receptors * Meissner = Light touch * Pacinian = Pressure/Vibration Pigment Cell * Melanocyte Immune Cell * Dendritic Cell Touch Cell * Merkel (Tactile) Cell Cancer Origins * Basal Cell Carcinoma = Stratum Basale * Squamous Cell Carcinoma = Stratum Spinosum * Melanoma = Melanocytes Sweat Glands * Eccrine = Cooling * Apocrine = Odor Burn Depths * 1st = Epidermis * 2nd = Epidermis + Dermis * 3rd = Epidermis + Dermis + Hypodermis Vitamin D Deficiency * Rickets * Osteomalacia This should cover essentially all of the major concepts from the four readings and is the type of material most likely to appear on a Module 2 Anatomy & Physiology exam