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

Integumentary System

The body system that includes the skin, hair, nails, sweat glands, and sebaceous glands.

Epidermis

The superficial layer of the skin, composed of keratinized stratified squamous epithelium; it is avascular.

Dermis

The deeper layer of the skin made of connective tissue, containing blood vessels, nerves, glands, and hair follicles.

Hypodermis

Also called the subcutaneous layer, it contains adipose tissue and is not technically part of the skin.

Keratinocytes

The most abundant cells in the epidermis that produce keratin.

Melanocytes

Cells in the skin that produce melanin, protecting against UV radiation.

Dendritic Cells

Immune defense cells in the epidermis that phagocytize pathogens.

Stratum Corneum

The outermost layer of the epidermis composed of dead keratinized cells that protect against abrasion and dehydration.

Meissner's Corpuscles

Touch receptors in the dermis responsible for light touch sensation.

Pacinian Corpuscles

Receptors in the dermis responsible for deep pressure and vibration sensation.

Sebaceous Glands

Glands that produce sebum, lubricating and waterproofing the skin.

Eccrine Sweat Glands

Sweat glands located throughout the body that are involved in thermoregulation.

Albinism

A genetic condition characterized by a lack of melanin production, resulting in pale skin and light sensitivity.

Basal Cell Carcinoma

The most common type of skin cancer that originates from the stratum basale.

ABCD Rule

A method for assessing moles for melanoma: Asymmetry, Border irregularity, Color variation, Diameter greater than 6 mm, Evolving.

Vitiligo

A disorder resulting from the loss of melanocyte activity, leading to white patches on the skin.

First-Degree Burn

A burn affecting only the epidermis, characterized by redness and pain.

Burn Depths

Classification of burns based on depth: 1st degree (epidermis), 2nd degree (epidermis + dermis), 3rd degree (epidermis + dermis + hypodermis).

Thermoregulation

The process by which the skin helps to maintain body temperature through mechanisms like sweating and blood vessel dilation.

Hair Follicle

A structure that surrounds the root of the hair and is involved in hair growth and production.

Keloid

A raised scar resulting from excessive collagen production during the healing process.

Bedsores

Injuries caused by prolonged pressure on the skin, leading to reduced blood flow and tissue death.