Integumentary System and Dermatology: Medical Terminology Study Guide

Dermatology and the Integumentary System

Introduction to Dermatology

Dermatology is the medical specialty focused on the anatomy, physiology, diseases, and treatments of the integumentary system, which includes the skin, nails, and subcutaneous tissue. Dermatologists utilize laboratory tests, diagnostic procedures, medical and surgical interventions, and pharmacological therapies to manage integumentary disorders.

Components of the Integumentary System

The integumentary system covers most of the body and is composed of the skin (the largest organ), nails, and subcutaneous tissue. Each component plays a vital role in protection, sensation, and homeostasis.

Anatomy of the Integumentary System

Word Parts and Terminology

• integument/o-: skin

• -ary: pertaining to

• cutane/o-: skin

• -ous: pertaining to

Layers of the Skin

The skin consists of two primary layers:

• Epidermis: The thin, outermost layer made of epithelial tissue. It contains both living and dead cells, with the surface cells filled with keratin for protection and waterproofing. The basal layer contains living cells and melanocytes, which produce melanin for UV protection.

• Dermis: The thick layer beneath the epidermis, composed of connective tissue, collagen, and elastin. It houses blood vessels, nerves, hair follicles, sebaceous glands, and sweat glands.

Subcutaneous Tissue

The subcutaneous (sub Q or subcu) tissue is a loose, connective layer beneath the dermis, primarily composed of adipose (fat) tissue and lipocytes. It functions to cushion, insulate, and protect internal organs.

Nails

Nails consist of five parts: nail plate, nail root, lunula, cuticle, and nail bed. The nail plate is the hard, protective covering, while the nail root produces living cells that form the lunula. As these cells grow, they die and harden to form the nail plate.

Hair

• Hair covers most of the body, with color and consistency varying by location.

• Melanocytes in the hair follicle provide color.

• Hair cells are filled with keratin, making the shaft strong.

• Piloerection occurs when the skin is cold, causing hair to stand up and form "goosebumps."

Glands of the Skin

• Sebaceous glands: Exocrine glands producing sebum (oil) that moisturizes the skin and hair.

• Sudoriferous glands: Sweat glands that secrete sweat containing water, sodium, and waste. Sweat is odorless until it contacts skin bacteria.

Dermatomes

A dermatome is an area of skin that sends sensory information to the spinal cord. Each dermatome is named according to the spinal nerve level it corresponds to (C, T, L, S).

Physiology of the Integumentary System

Protection

• The skin acts as the first line of defense against injury and infection.

• The acidic environment of the epidermis discourages microorganism growth.

• Keratin makes the skin waterproof.

• Sweat and sebum contain antibodies and enzymes that kill bacteria.

Repair

• Basal epidermal cells migrate to cover wounds.

• Deep wounds form blood clots and scabs, with new cells filling the wound.

Sensation

• Sensory receptors in the dermis detect touch, pressure, vibration, pain, and temperature.

• Nervous system processes these sensations for interpretation in the brain.

Vitamin D Synthesis

• UV rays convert epidermal cholesterol into vitamin D.

• Vitamin D is essential for calcium absorption.

• Sun exposure requirements vary by skin tone.

Thermoregulation

• Subcutaneous tissue stores fat and conserves heat.

• Piloerector muscles contract to generate heat.

• Sweat glands cool the skin.

• Dermal blood vessels dilate to release heat.

Homeostasis

• Homeostasis is the maintenance of internal balance and stability.

• Thermoregulation is a key aspect of homeostasis.

• The integumentary system signals other medical conditions through skin changes.

Diseases and Disorders of the Integumentary System

Edema

Edema is the accumulation of fluid in tissues, often resulting in swelling. Pitting edema occurs when pressure displaces tissue fluid, creating a deep indentation.

Skin Lesions

Skin lesions are abnormal changes in skin structure and appearance. They are classified by type, color, contents, and example.

Lesion	Description	Color	Contents	Example
Cyst	Elevated circular mound	Skin color or erythema	Semisolid or partly fluid filled	Acne sebaceous cyst
Fissure	Small, cracklike crevice	Erythema	None, some fluid exudate	Dry, chapped skin
Macule	Flat circle	Pigmented brown or black	None	Freckle, age spot
Papule	Elevated	Skin color or erythema	Solid	Acne pimple
Pustule	Elevated	White top	Pus	Acne whitehead
Scale	Flat to slightly elevated, thin flake	White	None	Dandruff, psoriasis
Vesicle	Elevated with pointed top	Erythema with transparent top	Clear fluid	Herpes, chickenpox, shingles
Wheal	Elevated with broad, flat top	Erythema with pale top	Clear fluid	Insect bites, urticaria

Skin Color Conditions

• Insufficient melanin production can result in pale skin or conditions such as albinism.

• Cyanosis is a bluish discoloration due to lack of oxygen, commonly seen in newborns.

• Necrosis is tissue death due to lack of blood supply, often following severe injury or frostbite.

• Vitiligo is a progressive autoimmune disorder causing depigmentation in patches.

Skin Injuries

• Burns can cause separation of the epidermis from the dermis, resulting in blisters and bullae.

• The Rule of Nines is used to estimate burn surface area for treatment.

• Keloids are enlarged scars that exceed the size of the original injury.

• Lacerations are deep cuts that expose subcutaneous tissue.

• Pressure injuries result from prolonged pressure, often in immobile patients.

Skin Infections

• Herpes simplex type 1 causes vesicles on the lips.

• Shingles (herpes zoster) produces vesicles and crusts along a dermatome.

• Tinea capitis is a fungal infection of the scalp, also known as ringworm.

Allergic Skin Conditions

• Contact dermatitis is an allergic reaction causing skin irritation, often triggered by chemicals.

Benign Neoplasms of the Skin

• Hemangiomas are bright red lesions caused by dilated blood vessels.

• Nevi (moles) can be pigmented, flat, or resemble port-wine stains.

• Syndactyly is the fusion of skin and soft tissues between fingers or toes.

Malignant Neoplasms of the Skin

• Malignant melanoma is characterized by asymmetry, irregular edges, varying colors, and increasing size.

Autoimmune Disorders of the Skin

• Psoriasis is a chronic autoimmune disorder causing red, scaly patches, commonly on elbows and knees.

Diseases of the Sebaceous Glands

• Acne vulgaris is triggered by increased sebaceous gland activity, resulting in papules and pustules.

• Rosacea causes erythema and dilated blood vessels, often affecting the face.

Diseases of the Nail

• Onychomycosis is a fungal infection of the nails, causing discoloration, thickening, and deformation.

Laboratory, Diagnostic, Medical, and Surgical Procedures

Botox Injection

• Botox is a diluted neurotoxin used for cosmetic and medical purposes, such as reducing wrinkles.

Skin Examination

• Dermatologists use magnifying lenses to examine skin lesions, which may require biopsy for diagnosis.

Wound Closure

• Lacerations can be closed with sutures or surgical glue. Deep sutures are absorbable, while skin sutures are removed after healing.

Hypodermic Injection

• Hypodermic injections deliver drugs into the subcutaneous tissue, using a needle angled at 45 degrees.

Punch Biopsy

• A punch biopsy removes a core of tissue including epidermis, dermis, and subcutaneous layers for diagnostic purposes.

Liposuction

• Liposuction is a surgical procedure to remove fat from targeted areas, improving body contour and symmetry.

Summary Table: Types of Skin Lesions

Lesion	Description	Color	Contents	Example
Cyst	Elevated circular mound	Skin color or erythema	Semisolid or partly fluid filled	Acne sebaceous cyst
Fissure	Small, cracklike crevice	Erythema	None, some fluid exudate	Dry, chapped skin
Macule	Flat circle	Pigmented brown or black	None	Freckle, age spot
Papule	Elevated	Skin color or erythema	Solid	Acne pimple
Pustule	Elevated	White top	Pus	Acne whitehead
Scale	Flat to slightly elevated, thin flake	White	None	Dandruff, psoriasis
Vesicle	Elevated with pointed top	Erythema with transparent top	Clear fluid	Herpes, chickenpox, shingles
Wheal	Elevated with broad, flat top	Erythema with pale top	Clear fluid	Insect bites, urticaria

Key Equations and Terms

Rule of Nines for Burn Assessment

The Rule of Nines is used to estimate the percentage of body surface area affected by burns:

• Head: 9%

• Chest: 9%

• Abdomen: 9%

• Each arm: 9%

• Genitals: 1%

• Each leg: 18%

• Back: 18%

Medical Terminology Word Parts

• dermat/o-: skin

• -logy: study of

• melan/o-: black

• -cyte: cell

• pil/o-: hair

• erect/o-: stand up

• -ion: action or condition

Conclusion

The integumentary system is essential for protection, sensation, thermoregulation, and homeostasis. Understanding its anatomy, physiology, and common diseases is fundamental for medical terminology students and healthcare professionals.