Study Notes on Dermatology

Chapter Goals

  • Layers of the Skin

    • Name the layers of the skin and the accessory structures associated with the skin.

  • Medical Terminology

    • Build medical words using the combining forms that are related to dermatology.

  • Lesions and Conditions

    • Identify lesions, signs, symptoms, and pathologic conditions that relate to the skin.

  • Laboratory Tests and Procedures

    • Describe laboratory tests and clinical procedures pertaining to the skin and recognize relevant abbreviations.

  • Application of Knowledge

    • Apply new knowledge to understanding medical terms in contexts like medical reports and records.

Introduction to the Skin

  • Function and Coverage

    • Skin as part of the integumentary system:

    • Weighs approximately 8 to 10 lbs.

    • Covers around 22 sq. ft. in an average adult.

Functions of Skin

  • Protection

    • Acts as a protective membrane for underlying structures.

  • Gland Functionality

    • Skin glands are involved in lubrication and cooling.

  • Sensory Reception

    • Functions as a receptor for various sensations (pain, temperature, pressure, and touch).

  • Thermoregulation

    • Helps maintain body temperature by interpreting signals from the brain's heat center.

Additional Functions

  • Sweat Production

    • Sweat glands produce a watery secretion that evaporates, leading to cooling.

  • Sebum Production

    • Sebaceous glands produce an oily secretion that lubricates skin and hair.

Structure of the Skin

  • Layers

    • Epidermis: Outermost, thin cellular membrane.

    • Dermis: Next layer; dense fibrous connective tissue.

    • Subcutaneous Tissue (Hypodermis): Thick layer of fat-containing tissue.

Skin Structure Details

  • Components

    1. Epidermis

    • Contains keratinized (horny) cells.

    1. Dermis

    • Contains blood vessels, nerve endings, and various glands.

    1. Subcutaneous Layer

    • Embedded with fat cells and larger blood vessels.

Accessory Organs of the Skin

  • Hair

    • Made of cells filled with the hard protein keratin:

    • Hair Follicles: Shafts that hold the hair.

    • Average adult has about five million hairs, with 100,000 on the head.

    • Melanocytes at the root contribute to the color.

    • Hair grows approximately 0.5 inch (1.3 cm) per month. Cutting does not affect growth.

  • Nails

    • Composed of hard keratin plates covering the toes and fingers:

    • Lunula: Half-moon shape at base of nail.

    • Cuticle: Skin portion at the base of the nail.

    • Paronychium: Soft tissue surrounding the nail.

  • Glands

    • Sebaceous glands: Secrete oily sebum into hair follicles to lubricate.

    • Sweat glands: Secrete moisture into pores to cool the skin. Both are prone to bacterial growth.

Vocabulary Related to Dermatology

  • Adipocyte: A fat cell.

  • Albino: A person with skin that is deficient in pigment.

  • Apocrine Sweat Gland: A large dermal exocrine gland located in axillary (armpit) and genital areas.

  • Basal Layer: Deepest region of the epidermis where new cells are formed.

  • Collagen: A structural protein found in skin and connective tissues.

  • Cuticle: Band of epidermis at the base and sides of the nail plate.

  • Dermis: The middle layer of skin rich in connective tissue.

  • Eccrine Sweat Gland: The most numerous sweat-producing glands in the skin.

  • Epidermis: The outermost layer of the skin.

  • Hair Follicle: The sac within which each hair grows.

  • Integumentary System: The skin and its accessory structures (hair and nails).

  • Keratin: A hard protein material found in epidermis, hair, and nails.

  • Melanin: Skin pigment produced by melanocytes.

  • Sebum: Oily substance secreted by sebaceous glands.

Combining Forms in Dermatology

  • adip/o: fat

  • albin/o: white

  • caus/o: burn, burning

  • cauter/o: heat, burn

  • cutane/o: skin

  • derm/o: skin

  • dermat/o: skin

  • diaphor/o: profuse sweating

  • erythem/o: redness

  • hidr/o: sweat

  • melan/o: black

  • onch/o: nail

  • slx/o: scaly, dry

  • trich/o: hair, hair follicle

Common Skin Lesions and Symptoms

  • Alopecia: Loss of hair where it usually grows.

  • Ecchymosis: Blue-black marks on the skin due to bleeding beneath the surface.

  • Petechia: Small pinpoint hemorrhages in the skin.

  • Urticaria (Hives): An acute allergic reaction characterized by red wheals.

Abnormal Skin Conditions

  • Acne: Skin eruption characterized by the papules and pustules due to increased sebum production.

  • Burns: Injury to tissue from heat, chemicals, electrical shock, etc.

  • Cellulitis: Diffuse infection of the skin.

  • Eczema: Inflammation of the skin with erythematous, papulovesicular lesions from allergies.

  • Gangrene: Tissue death due to loss of blood supply.

  • Impetigo: Contagious infection caused by bacteria, usually manifesting as sores.

  • Psoriasis: Chronic skin condition that presents with silver-gray scales.

  • Scabies: Infestation by mites causing itching.

  • Scleroderma: Disease characterized by the hardening of connective tissue.

  • Systemic Lupus Erythematosus (SLE): An autoimmune disease affecting skin, joints, and organs.

Skin Neoplasms

  • Benign

    • Keratosis: Thickened area of epidermis.

    • Nevus: Pigmented lesion.

    • Verruca (Warts): Viral skin growths.

  • Cancerous Lesions

    • Basal Cell Carcinoma: Malignant tumor from the basal cells of the epidermis.

    • Squamous Cell Carcinoma: Malignant tumor from the squamous cells.

    • Malignant Melanoma: Identified by the ABCDs:

    • Asymmetry

    • Border irregularity

    • Color variation

    • Diameter typically larger than 6mm.

    • Kaposi Sarcoma: Malignant growth characterized by cutaneous nodules.

Laboratory Tests and Clinical Procedures

  • Bacterial Analyses: Examine pus or fluid samples to detect microorganisms.

  • Fungal Tests: Scraping for cultures and microscopic examination.

  • Cryosurgery: Destroys tissue with subzero temperatures.

  • Curettage: Scrapes lesions with a curet.

  • Electrodesiccation: Burns tissue with an electric spark.

  • Mohs Surgery: Removes thin skin layers for microscopic examination.

  • Skin Biopsy: Punch and shave technique to remove tissue for examination.

Common Abbreviations in Dermatology

  • ABCDE: Characteristics of melanoma (Asymmetry, Border, Color, Diameter, Evolution).

  • Bx: Biopsy.

  • Derm.: Dermatology.

  • PPD: Purified protein derivative.

  • SLE: Systemic lupus erythematosus.

  • SC: Subcutaneous.

Review Sheets for Dermatological Terms

  • Comprehensive review sheets summarize combining forms, suffixes, and their meanings related to dermatology, providing the essential vocabulary for further studies in skin health and conditions.