Dermatology

Introduction to Integumentary System

• Integument Components:

  • Skin

  • Hair

  • Nails

  • Glands

• Significance of Skin:

  • Largest organ, accounts for 20% body weight.

Functions of the Integumentary System

• Primary Functions:

  • Protection against microorganisms, UV radiation, and loss of fluid.

  • Mechanical stress resistance.

• Additional Roles:

  • Regulates body temperature

  • Vitamin D production

  • Immune surveillance

  • Provides sensory feedback (touch, pain, pressure)

Skin Anatomy

• Layers:

  • Epidermis:

    • Composed of keratinocytes, melanocytes, Langerhans cells, Merkel cells

  • Dermis:

    • Contains collagen, elastin, blood vessels, glands, and nerves

  • Subcutaneous Layer (Hypodermis):

    • Composed of fat cells and larger vessels/nerves

Epidermis Details

• Cell Types:

  • Keratinocytes: Produce keratin

  • Melanocytes: Produce melanin

  • Langerhans Cells: Antigen-presenting cells

  • Merkel Cells: Involved in touch sensation

Dermis Composition

• Characteristics:

  • Beneath the epidermis

  • Contains hair follicles, sebaceous glands, sweat glands

• Subcomponents:

  • Collagen and elastin in gel-like matrix

  • Blood and lymph vessels, nerves included

Glandular Functions

• Sebaceous Glands:

  • Secrete sebum for hair/skin lubrication

  • Stimulated during puberty

• Sweat Glands:

  • Eccrine: For thermoregulation

  • Apocrine: Limited proven function, possibly for pheromones

Aging Effects on the Skin

• Changes:

  • Thinning, dryness, wrinkling, reduced elasticity

• Causes:

  • Reduced sebaceous and sweat glands

  • Decreased melanocytes and Langerhans cells

Skin Lesions

• Primary Lesions:

  • Macule: Flat, <1 cm

  • Papule: Raised, <1 cm

  • Plaque: >1 cm raised plateau

  • Nodule: 1-2 cm raised, firm lesion

  • Vesicle/Bulla: Fluid-filled blisters

  • Pustule: Filled with pus

  • Wheal: Elevated area of cutaneous edema

Secondary Skin Lesions

• Result from primary lesions; examples include:

  • Scale: Flaking skin

  • Lichenification: Thickening from chronic irritation

  • Keloid: Excessive scarring

  • Excoriation: Loss of epidermis due to scratching

Pressure Ulcers

• Description:

  • Also known as bedsores; localized skin injury from pressure

• Stages:

  • Stage 1: Non-blanchable erythema

  • Stage 2: Partial thickness skin loss

  • Stage 3: Full thickness loss involving subcutaneous tissue

  • Stage 4: Full thickness loss with muscle/bone involvement

• Prevention/Treatment:

  • Relieving pressure, maintaining hygiene, dressing changes, potential surgery

Common Skin Disorders

• Eczema/Atopic Dermatitis:

  • Characterized by intense itching and secondary lesions

• Contact Dermatitis:

  • Allergic reaction to specific allergens (e.g., poison ivy)

• Psoriasis:

  • Autoimmune condition causing rapid skin cell turnover, leading to plaques

• Acne:

  • Inflammatory skin condition affecting hair follicles

Infectious Skin Conditions

• Herpes Simplex Virus:

  • HSV-1 mainly causes cold sores; HSV-2 causes genital lesions

• Fungal Infections (Tinea):

  • Include athlete's foot and jock itch

• Bacterial Infections:

  • Folliculitis and cellulitis caused by staphylococcus

Skin Cancer Types

• Basal Cell Carcinoma:

  • Most common type; slow-growing, rarely metastasizes

• Squamous Cell Carcinoma:

  • Second most common; grows faster but less metastasis

• Malignant Melanoma:

  • Most aggressive form; high potential for metastasis

Pediatric Integumentary Diseases

• Chickenpox:

  • Caused by varicella; highly contagious with vesicular lesions

• Pediculosis:

  • Infestation of lice causing significant itching

Integration and Application

• Utilize knowledge of skin structures and functions in assessing dermatological conditions.

• Relate symptoms presented in case studies to specific skin disorders and appropriate treatments.

Questions and Further Reading

• Reading Assignments:

  • Chapter 47 & 48 from McCance & Huether textbook

• Prepare for application-based questions as per case studies presented.