Advanced Medical Terminology: Integumentary System Study Guide

Functions and Overview of the Integumentary System

  • The integumentary system consists of the skin (the integument) and its accessory structures including hair, nails, and glands.
  • Primary Function: The skin acts as the first line of defense in protecting the body from disease by providing an external barrier.
  • Additional Functions:
    • Thermoregulation: Helps regulate the temperature of the body.
    • Sensory Perception: Provides information about the environment through the sense of touch.
    • Synthesis of Vitamin DD: Assists in the synthesis of Vitamin DD, which is essential for the normal formation of bones and teeth.
    • Waste Elimination: Helps eliminate waste products from the body.
  • The skin is the largest organ of the body.
  • Accessory Structures: These include hair, nails, and two specific types of glands:
    • Sebaceous Glands: Also known as oil glands.
    • Sudoriferous Glands: Also known as sweat glands.
  • Medical Specialty: The study of skin, hair, and nails is called dermatology. A dermatologist is a specialist who focuses on this area.

Anatomy and Physiology of the Skin

  • The skin is composed of two primary layers and sits atop a layer of connective tissue.
  • Epidermis: The outermost layer of the skin.
    • Composed of several different layers known as stratum or strata (singular: stratum).
    • Made of epithelial tissue, specifically referred to as stratified squamous epithelium because of its microscopic scaly appearance (squamous means scaly).
    • It is avascular, meaning it contains no blood vessels and has a limited blood supply.
    • Stratum Germinativum: The basal or bottom layer where constant activity occurs.
      • New skin cells are formed here.
      • Contains melanocytes, which produce melanin (pigment). Clumping of melanin results in birthmarks, age spots, and freckles. Melanin secretion increases with exposure to ultraviolet light.
    • Stratum Corneum: The top or outermost layer.
      • Cells move from the basal layer toward the stratum corneum and become keratinocytes.
      • These cells are filled with keratin, a hard protein material that provides waterproof properties to help retain moisture within the body.
  • Dermis (Corium): The thick, underlying inner layer of the skin composed of vascular connective tissue.
    • Papillary Layer: The upper thin layer composed of protein and collagen fibers. It regulates blood flow through an extensive vascular supply.
    • Reticular Layer: The lower, thicker layer also composed of collagen fibers. It houses the hair follicles, sweat glands, and sebaceous glands.
  • Hypodermis (Subcutaneous Layer): Attached to the dermis, it is composed of connective tissue, mainly fat or adipose tissue.

Accessory Structures: Glands, Hair, and Nails

  • Sudoriferous (Sweat) Glands:
    • Located in the dermis.
    • Function in thermoregulation by secreting sweat (perspiration) through tiny openings called pores.
    • Most abundant in the soles of the feet, palms of the hands, armpits, upper lip, and forehead.
  • Sebaceous (Oil) Glands:
    • Secrete an oily acidic substance called sebum.
    • Sebum lubricates hair and the skin surface. Its acidic nature is key in inhibiting bacterial growth.
  • Hair:
    • Hair Follicles: The roots and their coverings located in the dermis.
    • Hair Shaft: The visible part of the hair.
    • Papilla (plural: Papillae): A nipple-shaped structure underneath the follicle enclosing capillaries.
    • Epithelial cells on top of the papilla reform the hair shaft. If these cells die, hair cannot regenerate, resulting in hair loss.
    • Function: Assists in thermoregulation. Piloerection occurs when hair stands on end to hold a layer of air as insulation near the body during cold.
  • Nails:
    • Protect the dorsal surfaces of the distal bones of the fingers and toes.
    • Nail Body (Nail Plate): The visible part of the nail.
    • Nail Root: Located in a groove under a small fold of skin at the base.
    • Nail Bed: Highly vascular tissue under the nail. It appears pink when blood is oxygenated and purple/blue when blood is oxygen deficient.
    • Lunula: The moon-like white area at the base of the nail where new growth occurs.
    • Cuticle (Eponychium): The small fold of skin above the lower part of the nail.
    • Paronychium: The fold of skin near the sides of the nail.
    • Note for students: Do not confuse "strata" (layers) with "striae" (stretch marks).

Pathology: Skin Lesions and Burns

  • Skin Lesion: Any visible, localized abnormality of skin tissue.
    • Primary Lesions: Early skin changes that have not undergone natural evolution or manipulation.
    • Secondary Lesions: Result from the natural evolution or manipulation of a primary lesion.
  • Burns: Injuries to tissues resulting from exposure to thermal, chemical, electrical, or radioactive agents.
  • The Rule of Nines: A categorization method for burns higher than second degree that divides the body into percentages (mostly multiples of nine):
    • Head and Neck: 9%9\%
    • Each Upper Limb: 9%9\%
    • Front of Torso: 18%18\%
    • Back of Torso: 18%18\%
    • Each Lower Limb: 18%18\%
    • Genital Area: 1%1\%
  • Burn Severity Classification:
    • Superficial Burn (First-Degree): Damages only the epidermis. Characterized by redness (erythema), tenderness, and hyperesthesia (sensitivity), but no scar development.
    • Partial Thickness Burn (Second-Degree): Affects the epidermis and part of the dermis. High redness, blisters, and pain. Scar development is possible.
      • Superficial Partial Thickness: Burn exceeds the papillary level.
      • Deep Partial Thickness: Extends further into the reticular layer.
    • Full Thickness Burn (Third-Degree): Damages epidermis, dermis, and subcutaneous tissue. Skin may appear deep red, pale gray, brown, or black. It is typically painless because nerve endings are destroyed. Scar formation is likely.
    • Deep Full Thickness Burn (Fourth-Degree): Rare category describing a burn extending beyond subcutaneous tissue into muscle and bone.

Pharmacology and Drug Administration

  • Routes of Administration:
    • Hypodermic: General term for any injection under the skin.
    • Intradermal (ID): Injection within the dermis (intracutaneous).
    • Subcutaneous: Injection into the fat layer beneath the skin.
    • Topical: Applied directly onto the skin (cream, gel, lotion, ointment).
    • Transdermal Therapeutic System: Non-absorbent adhesive patch with a gel-like material for timed release of medication (e.g., nitroglycerin for angina pectoris or nicotine for smoking cessation).
  • Specific Drug Classes:
    • Anesthetic Agents: Cause loss of sensation (e.g., Lidocaine/Xylocaine, Benzocaine/OraGel).
    • Antibacterials: Treat/prevent bacterial growth (e.g., Erythromycin/Erygel, Clindamycin/Benzoclin). Triple antibiotic ointments often contain Bacitracin, Polymyxin B, and Neomycin (Neosporin). Silver Sulfadiazine (Silvadine) and Mupirocin (Bactroban) treat wound infections.
    • Antifungals: Treat fungal infections (e.g., Nystatin/Nystop, Butenafine/Lotrimin Ultra, Ciclopirox/Loprox).
    • Antihistamines: Suppress allergic responses (e.g., Diphenhydramine/Benadryl, Cetirizine/Zyrtec, Loratadine/Claritin).
    • Anti-inflammatories: Reduce inflammation (e.g., Prednisone, Aspirin, Hydrocortisone).
    • Antipsoriatics: Treat psoriasis (e.g., Anthralin, Calcipotriene/Dovonex).
    • Antiseptics: Destroy surface microbes (e.g., Iodine, Chlorhexidine/Hibisat).
    • Antivirals: Treat viral infections like HSV1 (cold sores), genital herpes, and shingles (herpes zoster) (e.g., Valacyclovir/Valtrex, Acyclovir/Zovirax).
    • Emollients: Soften and moisturize skin (e.g., Aveeno, Eucerin).
    • Immunomodulators/Immunosuppressants: Suppress immune systems for atopic dermatitis or eczema (e.g., Pimecrolimus, Tacrolimus).
    • Keratolytics: Shed dead skin to treat warts, calluses, or acne (e.g., Salicylic Acid/Compound W, Cantharidin, Podofilox/Condylox).
    • Pediculicides: Destroy lice (e.g., Malathion/Ovide, Lindane/Kwell, Permethrin/Nix).
    • Protectives/Protectants: Sunscreens/Sunblocks (Oxybenzone, Avobenzone) protecting against UVA and UVB light.
    • Psoralens: Absorb UVA light to treat skin conditions like psoriasis (e.g., Methoxsalen/Uvadex).
    • Retinoids: Derived from Vitamin A; alter hair/skin growth to treat acne and wrinkles (e.g., Tretinoin, Isotretinoin, Tazarotene/Tazorac).
    • Scabicides: Destroy mites and scabies (e.g., Permethrin/Elimite, Crotamiton/Eurax).

Complementary and Alternative Methods of Treatment

  • Herbal Medicine:
    • Aloe Vera: Used to treat sunburn and stomach ulcers.
    • Tea Tree Oil: Used for its antibacterial, antiviral, and antifungal properties to treat boils, wound infections, and acne.
  • Essential Oils: Helpful for dry, flaky skin, decubitus ulcers (pressure sores), diabetic ulcers, and herpes infections (HSV1 and zoster).
  • Natural Astringents: Witch hazel and calamine lotion are used to dry and contract the skin.