Integumentary System: Structure, Function, and Medical Terminology

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Ch.3 Integumentary System

Overview of the Integumentary System

The integumentary system is a complex set of organs that includes the skin and its accessory structures such as hair, nails, sweat glands, and sebaceous glands. The skin is the largest organ of the human body and serves as a protective barrier between the internal environment and the external world.

Skin Layers:
- Epidermis: The outermost layer, composed of stratified squamous epithelial cells. It is avascular (lacks its own blood supply) and is primarily responsible for protection.
- Dermis: The inner layer, made of connective tissue. It contains blood vessels, nerve endings, hair follicles, sweat glands, and sebaceous glands. The dermis binds the epidermis to deeper tissues.
- Subcutaneous Layer (Hypodermis): A fatty layer that separates the dermis from deeper tissues, providing insulation and cushioning.
Cutaneous Membrane: The collective term for the epidermis and dermis.

Cross-section of skin showing epidermis, dermis, hypodermis, hair follicle, glands, and blood vessels

Functions of the Integumentary System

The integumentary system performs several vital functions essential for maintaining homeostasis and protecting the body.

Protection: Acts as a barrier against chemicals, pathogens, and prevents loss of critical body fluids.
Regulation: Controls body temperature through evaporation (sweating), vasoconstriction, and vasodilation.
Secretion: Sebaceous glands secrete sebum to lubricate hair and skin; sweat glands aid in excretion of waste products.
Sensation: Contains nerve endings that sense temperature, pain, touch, and pressure.

Illustration of sweating and temperature regulation Illustration of skin as a barrier to pathogens

Accessory Structures of the Integumentary System

Hair

Hair is composed of dead, keratinized cells and serves protective and sensory functions. Each hair consists of a shaft (visible part) and a root (embedded in the follicle). The root receives nourishment from a loop of capillaries called the papilla. The arrector pili muscle, a small smooth muscle, contracts to cause goosebumps.

Diagram of hair follicle, shaft, root, and papilla

Sweat and Sebaceous Glands

Sebaceous Glands: Secrete sebum, an oily substance that lubricates skin and hair. Sebum production increases during adolescence and decreases with age.
Sweat Glands: Secrete sweat through ducts onto the skin surface, aiding in temperature regulation and excretion of metabolic waste. Both sweat and sebaceous glands are classified as exocrine glands.

Cartoon of a sweat gland

Nails

Nails are flat plates of hard keratin that cover the ends of fingers and toes. They are connected to deeper tissue by the nail bed. The cuticle is a soft tissue at the base of the nail, protecting the nail root. The lunula is the light-colored, half-moon-shaped area at the base of the nail.

Anatomy of the nail and cross-section showing nail bed and cuticle

Medical Terminology: Word Building in the Integumentary System

Common Combining Forms

Combining Form	Definition	Memory Tool
integument/o	covering	Integumentary system
cutane/o, derm/o, dermat/o	skin	Cutaneous, dermatologist
aden/o	gland	Glands add-in secretions
sudor/o, hidr/o	sweat	Suit causes hydration
seb/o	sebum, oil	Sebum
adip/o, lip/o	fat	Lip/o/suction
sarc/o	flesh, connective tissue	Sarc/oma
bas/o	base	Basement
kerat/o	hard, horny tissue	Crunchy carrot
cellul/o	little cell	Cell
follicul/o	little follicle	Hair follicle holds the hair
angi/o	vessel	Angiogenesis
trich/o, pil/o	hair	Tricky pillow fight
onych/o, ungu/o	nail	Onyx nails come unglued

Skin Characteristics and Colors

Combining Form	Definition	Memory Tool
ichthy/o	dry, scaly	Itchy dry skin
xer/o	dry	Xero moisture
pachy/o	thick	Pack it on
scler/o	hard	Squirrel cracks hard nuts
rhytid/o	winkle	Get rid of wrinkles
cyan/o	blue	Cyan blue
erythr/o	red	Erythrocyte
albin/o	white	Albinism
melan/o	black	Melanin
jaund/o	yellow	Jaundice

Dry, cracked surface representing xer/o or ichthy/o Cyan color swatch representing cyan/o Person with pale skin and light hair representing albin/o Person with yellowish skin and eye representing jaund/o Hands of different skin colors representing melan/o

Pathological Conditions and Related Terms

Combining Form	Definition	Memory Tool
caus/o	burn, burning	Cause of fire
prurit/o	itching	Itchy cat purrs
py/o	pus	Pyo
septic/o	infection	Septic water
necr/o	death	Necromancer
pedicul/o	body louse	Pedicure
myc/o	fungus	Mic drop
actin/o	ray	Action rays
kel/o	tumor	Keloid scar

Necromancer representing necr/o (death)

Descriptive and Transplantation Terms

Combining Form	Definition	Memory Tool
aut/o	self	Autograph
xen/o	foreign	Xtra-Enigma
cauter/o	to burn	Cauterize
cry/o	cold	Cryotherapy

Integumentary System Vocabulary: Pathology and Procedures

Common Pathological Conditions

Medical Term	Description	Memory Tool
Varicella	Viral skin infection (chicken pox)	Chicken pox
Monkeypox	Flu-like viral infection with severe blisters	Monkeypox
Furuncle	Bacterial infection of hair follicle (boil)	Furry Uncle
Scabies	Skin infection by mites	Itch Mite
Tinea	Fungal skin disease (ringworm)	Tiny Rings
Ecchymosis	Bruise	Eek, a bruise!
Vitiligo	Skin depigmentation	Vanilla Skin
Eczema	Superficial dermatitis marked by loss of moisture	Moisture Exit-ma
Hirsutism	Excessive hair growth	Suit of hair
Psoriasis	Buildup of silver scale patches	Layers of Earth
Urticaria	Hives	Ur tie carries hives

Diagnostic and Therapeutic Procedures

Medical Term	Description
Culture & Sensitivity	Growing, collecting, and testing pathogens for antibiotic sensitivity
Biopsy	Removal of tissue for examination and diagnosis
Frozen section	Biopsy taken during surgery and later frozen for analysis
Fungal scrapings	Sampling of skin, hair, or nail from an infected area for fungal testing
Debridement	Removal of dead or infected tissue
Curettage	Specific form of debridement using a scraper

Pharmacology Related to the Integumentary System

Medical Term	Description	Memory Tool
Anticoagulant	Prevents blood from clotting	Anti Clog
Antineoplastic	Slows growth of malignant tumors	Against new growth
Agonist	Binds to a cell and triggers a response	Agent turns cell ON
Antagonist	Binds to a cell and blocks a response	Anti-agent turns cell OFF
Bioavailability	Amount of medication that enters bloodstream and causes a desired effect	Biologically Available
Corticosteroids	Synthetic anti-inflammatory medication	Cortex, stressed needs ointment

Summary Table: Key Terms and Their Functions

Structure/Term	Function/Definition
Epidermis	Outermost, avascular layer of skin; protection
Dermis	Connective tissue layer with vessels, nerves, glands
Hypodermis	Fatty layer for insulation and cushioning
Hair	Protection, sensation; made of keratin
Nails	Protects finger/toe tips; made of keratin
Sebaceous glands	Secrete sebum for lubrication
Sweat glands	Secrete sweat for temperature regulation and excretion