Study Guide Module 2
MODULE 2 STUDY GUIDE
The Integumentary System
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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
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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
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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
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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
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THICK VS THIN SKIN
Thick Skin
Found on:
* Palms
* Soles
Contains:
* Stratum lucidum
Thin Skin
Found everywhere else
Does not contain:
* Stratum lucidum
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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
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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
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DERMAL FIBERS
Collagen
Provides:
* Strength
* Support
* Water retention
Elastin
Provides:
* Elasticity
* Stretching ability
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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
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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
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CHAPTER 6: FUNCTIONS OF THE SKIN
Protection
Protects against:
* Microorganisms
* Chemicals
* UV radiation
* Water loss
* Physical trauma
Dermicidin:
* Antimicrobial substance in sweat
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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
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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
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Vitamin D Synthesis
UV exposure stimulates vitamin D production.
Vitamin D helps:
* Calcium absorption
* Bone health
* Immune function
Deficiency causes:
Rickets
Children
Osteomalacia
Adults
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Communication
Examples:
* Facial expressions
* Goosebumps
* Sweating
* Hair patterns
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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
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Hair Layers
1. Medulla
2. Cortex
3. Cuticle
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Hair Functions
* Protection
* Thermoregulation
* Sensation
* Communication
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Hair Growth
Average:
* 0.3 mm/day
Normal loss:
* About 50 hairs/day
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Hair Color
Determined by:
* Melanin
Gray hair:
* Reduced melanin production
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Arrector Pili Muscle
Functions:
* Causes goosebumps
* Helps retain heat
Controlled by:
* Sympathetic nervous system
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Alopecia
Definition:
* Hair loss
Pattern baldness:
* Hormonal and genetic
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CHAPTER 8: NAILS
Functions:
* Protection
* Support for grasping
Structures:
* Nail body
* Nail root
* Nail matrix
* Nail bed
* Lunula
* Cuticle (eponychium)
* Hyponychium
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CHAPTER 9: GLANDS
Eccrine Sweat Glands
Location:
* Most of body
Functions:
* Thermoregulation
Secrete:
* Water
* Salt
* Waste products
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Apocrine Sweat Glands
Location:
* Armpits
* Genital regions
Characteristics:
* Empty into hair follicles
* Produce odor after bacterial breakdown
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Sebaceous Glands
Produce:
* Sebum
Functions:
* Lubricates skin
* Waterproofs skin
* Prevents drying
* Antibacterial effects
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CHAPTER 10: SKIN CANCER
Basal Cell Carcinoma
Origin:
* Stratum basale
Characteristics:
* Most common
* Least likely to metastasize
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Squamous Cell Carcinoma
Origin:
* Stratum spinosum
Characteristics:
* More aggressive
* Can metastasize
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Melanoma
Origin:
* Melanocytes
Characteristics:
* Most deadly
* Highly metastatic
ABCDE Rule
A = Asymmetry
B = Border irregularity
C = Color variation
D = Diameter > 6 mm
E = Evolving
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CHAPTER 11: SKIN DISORDERS
Eczema
Symptoms:
* Dry skin
* Itching
* Rash
* Inflammation
Treatment:
* Moisturizers
* Corticosteroids
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Acne
Cause:
* Excess sebum
* Keratin buildup
* Bacterial infection
Common locations:
* Face
* Chest
* Back
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CHAPTER 12: WOUND HEALING
Steps:
1. Clot Formation
Stops bleeding
2. Scab Formation
3. Fibroblast Activity
Produces collagen
4. Capillary Growth
5. Epidermal Repair
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CHAPTER 13: BURNS
First-Degree Burn
Damage:
* Epidermis only
Symptoms:
* Redness
* Pain
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Second-Degree Burn
Damage:
* Epidermis + part of dermis
Symptoms:
* Blisters
* Swelling
* Pain
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Third-Degree Burn
Damage:
* Epidermis
* Dermis
* Hypodermis
Characteristics:
* Nerve destruction
* Often painless initially
* Requires grafting
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Rule of Nines
Head and neck = 9%
Each arm = 9%
Each leg = 18%
Trunk = 36%
Genitalia = 1%
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CHAPTER 14: SCARS
Scar Tissue
Produced by:
* Fibroblasts
Contains:
* Collagen
Lacks:
* Hair follicles
* Sweat glands
* Sebaceous glands
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Keloid
Raised scar due to excessive collagen
Atrophic Scar
Sunken scar
Examples:
* Acne scars
* Chickenpox scars
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CHAPTER 15: PRESSURE AND FRICTION INJURIES
Bedsores
Cause:
* Prolonged pressure
Result:
* Reduced blood flow
* Tissue death
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Stretch Marks
Cause:
* Rapid growth
* Pregnancy
* Weight gain
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Calluses
Cause:
* Repeated friction
Result:
* Thickened epidermis
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Corns
Specialized calluses
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Blisters
Cause:
* Friction
Result:
* Fluid accumulation between skin layers
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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
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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
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