skin

CHAPTER 13: Skin, Hair, and Nails

Overview

  • Skin is the body's largest organ system, covering approximately 20 square feet of surface area in adults.
  • Functions of skin:
    • Serves as a protective barrier (sentry) for the body.
    • Composed of two primary layers:
      • Epidermis: Outer layer, highly differentiated.
        • Basal Cell Layer: Generates new skin cells.
        • Outer Horny Cell Layer: Composed of dead keratinized cells.
      • Dermis: Inner supportive layer of skin, comprising:
        • Connective tissue or collagen.
        • Elastic tissue.
    • Beneath the dermis is a subcutaneous layer of adipose tissue that:
      • Stores fat for energy.
      • Provides insulation for temperature regulation.
      • Assists in the physical protection of underlying structures.

Skin Color

  • Skin color arises from three sources:
    • Melanin: Brown pigment responsible for skin's color.
    • Carotene: Yellow-orange pigment contributing to skin hue.
    • Red/Purple Tones: From the underlying vascular bed.
  • Individuals exhibit varying amounts of each pigment (red, yellow, brown) and their relative proportions affect overall skin color.
  • Skin thickness and edema (swelling) can also modify appearance.

Hair, Sebaceous & Sweat Glands

  • Hair:

    • Composed of keratin, presenting in the form of hair shafts and bulb matrices.
    • Types of hair include:
      • Vellus Hair: Fine, soft hair.
      • Terminal Hair: Coarser and thicker.
    • Hair follicles feature cyclical growth, alternating between active and resting phases.

  • Sebaceous Glands:

    • Produce sebum, a lipid substance secreted through hair follicles.
    • Functions of sebum include:
      • Lubrication of skin.
      • Formation of an emulsion on skin surface.

  • Sweat Glands:

    • Eccrine Glands: Primarily produce sweat for thermoregulation.
    • Apocrine Glands: Produce a milky secretion, opening into hair follicles, typically associated with emotional sweating.

Structure of Nails

  • Nails are hard plates composed of keratin located on the dorsal edges of fingers and toes.
  • Key components of nails include:
    • Nail Matrix: Area where nail growth occurs.
    • Nail Bed: Underlies the nail plate.
    • Cuticle: Skin at the base of nails.
    • Lateral Nail Folds: Skin surrounding the sides of the nails.
    • Lunula: The visible part of the matrix at the nail base.
    • Nail Plate: Hard exterior of the nail.

Functions of Skin

  • Skin performs several essential functions, including:
    • Protection: Shields against mechanical injury and invasion.
    • Prevents Penetration: Acts as a barrier to pathogens.
    • Perception: Houses sensory receptors that provide information about the external environment.
    • Temperature Regulation: Assists in maintaining the body's temperature.
    • Identification: Unique skin features aid in personal identification.
    • Communication: Contributes to non-verbal cues.
    • Wound Repair: Facilitates healing processes.
    • Absorption and Excretion: Capable of absorbing substances and excreting waste via sweat.
    • Production of Vitamin D: Synthesizes vitamin D upon exposure to ultraviolet light.

Skin Changes Across Life Stages

  • Infants:

    • Lanugo: Fine downy hair present at birth.
    • Vernix Caseosa: Thick, cheesy substance covering newborn skin, offering protection.
    • Milia: Small white bumps caused by sebum retention.

  • Children:

    • Epidermis thickens, darkens, and gains lubrication. Accelerated hair growth occurs.

  • Adolescents:

    • Increased secretions from apocrine sweat glands and fat deposits begin to increase. Development of secondary sexual characteristics.

  • Pregnant Women:

    • Metabolism increase results in elevated sweat and sebaceous gland activity.
    • Hormonal changes lead to skin color alterations and additional fat storage for nursing.

  • Aging Adults:

    • Reduced skin elasticity leads to sagging and formation of skin folds.
    • Decline in sweat and sebaceous gland function results in dry skin.
    • Senile Purpura: Discoloration from increased capillary fragility.
    • Slower cell replacement and healing processes are observed, along with decreased melanocyte function resulting in graying and thinning hair.

Key Health History Questions

  • For Adults:

    • Previous history of skin diseases or allergies, changes in pigmentation, conditions such as psoriasis or eczema, and hair loss.
    • Changes in nails, excessive dryness, pruritus, bruising, or the presence of rashes/lesions.

  • For Infants and Children:

    • Notable conditions include birthmarks, changes in skin color, presence of rashes, burns, or exposure to any communicable diseases.
    • Observation of habits such as nail-biting or hair twisting is advised.

  • For Aging Adults:

    • Delayed wound healing, changes in the feet, history of diabetes, or peripheral vascular disease.

Objective Data Collection

  • Preparation:
    • Focus on skin characteristics to avoid omissions during examination.
  • Equipment Required:
    • Strong direct lighting, gloves, penlight, small centimeter ruler, and potentially a magnifying glass for detailed assessments.
  • Method:
    • Conduct a comprehensive physical examination integrated with skin assessment, scrutinizing outer skin surface first.
    • Special attention to intertriginous areas (skinfolds) such as under large breasts and groins.
    • Inspect feet and toenails rigorously.

Inspection and Palpation of the Skin

  • Key aspects to assess include:
    • Color: Overall pigmentation and presence of freckling, moles, or birthmarks, noting wide-ranging color changes such as pallor, erythema, cyanosis, or jaundice.
    • Temperature: Use the backs of hands, ensuring equal warmth bilaterally to assess circulatory status.
      • Look for indicators of hypothermia or hyperthermia.
    • Moisture Level: Assess diaphoresis or dehydration.
    • Texture and Thickness: Normal skin should feel smooth and firm, observing for thickened areas or signs of edema.
    • Mobility and Turgor: Evaluate skin elasticity; observe for bruising or variations like tattoos.
    • Lesions: Document the following criteria if lesions are present:
      • Color, elevation, shape, size, location, distribution on the body, exudate characteristics.

Hair Inspection

  • Color: Determined by melanin production.
  • Texture: Ranges from fine to thick; may be affected by hair care products.
  • Distribution: Evaluated through Tanner staging for gender-specific patterns.
  • Lesions: Inspect scalp by dividing hair into sections.

Nail Inspection

  • Shape and Contour: Use profile sign; angle at nail base should be approximately 160 degrees.
  • Consistency: Observed for smoothness and regularity, noting any brittleness.
  • Color: Should appear translucent with a pink nail bed underneath.
  • Capillary Refill: Test peripheral circulation by observing return of color after blanching the nail edge.

Health Promotion and Self-Care

  • Teach skin self-examination with the ABCDEF rule for detecting suspicious lesions:
    • A: Asymmetry.
    • B: Border irregularity.
    • C: Color variations.
    • D: Diameter greater than 6 mm.
    • E: Elevation or evolution.
    • F: “Funny looking” – any lesions that appear different from others.

Developmental Competence

  • Observations for skin color and pigmentation variations in infants and children include:

    • Mongolian spots, café-au-lait spots, harlequin color change.
    • Temporary cyanotic conditions and acrocyanosis.
    • Vascularity concerns like nevus simplex.

  • Adolescents:

    • Typically experience acne and comedonal changes.

  • Pregnancy Changes:

    • May exhibit striae, linea nigra, and chloasma.

  • Aging Factors:

    • Skin color presentations such as senile lentigines and keratoses, xerosis, decreased hair and nail growth, and brittleness in nails.

Shapes and Configurations of Lesions

  • Lesion types include:
    • Target or Iris: Resembles the iris of an eye with concentric rings.
    • Linear: Appears as a scratch or streak.
    • Polycyclic: Concentric rings that merge.
    • Zosteriform: Linear along a unilateral nerve route.
    • Annular or Circular: Begins in the center and expands outward.
    • Confluent: Lesions that merge together.
    • Discrete: Separate and distinct lesions.
    • Grouped: Cluster arrangements of lesions.
    • Gyrate: Twisted or coiled, resembling snakes.

Primary Skin Lesions

  • Macules: Flat, circumscribed color changes, < 1 cm.
  • Papules: Superficial thickening of the epidermis.
  • Patches: Larger macules, > 1 cm.
  • Plaques: Coalesced papules, broader than 1 cm.
  • Nodules: Solid lesions, > 1 cm, extending deeper into the dermis.
  • Wheals: Transient, raised, irregular lesions from edema.
  • Tumors: Larger, can be benign or malignant.
  • Vesicles: Fluid-filled cavities < 1 cm.
  • Cysts: Encapsulated fluid-filled cavities.
  • Bulla: Larger than 1 cm, easily ruptured blisters.
  • Pustules: Purulent filled cavities, elevated.

Secondary Skin Lesions

  • Debris on Skin Surfaces:

    • Crust: Thickened exudate.
    • Scale: Compact flakes from shedding keratin cells.

  • Breaks in Skin Continuity:

    • Fissures: Linear cracks into the dermis.
    • Erosions: Scooped out depressions.
    • Ulcers: Deeper dermal depressions with potential for bleeding.
    • Excoriations: Superficial scrapes caused by scratching.
    • Scars: Permanent fibrotic changes after healing.
    • Atrophic Scars: Thinned tissue after healing.
    • Lichenifications: Thickened skin from prolonged scratching.
    • Keloids: Excessive scar tissue beyond the original injury site.

Skin Injury Stages

  • Stage I: Non-blanchable erythema.
  • Stage II: Partial-thickness skin loss.
  • Stage III: Full-thickness skin loss.
  • Stage IV: Full-thickness skin/tissue loss.
  • Deep Tissue Pressure Injury (DTPI): Related to medical devices.

Vascular & Pigmented Lesions

  • Types of Hemangiomas include:

    • Port-Wine Stain (Nevus Flammeus): Vascular birthmark.
    • Strawberry Mark (Immature Hemangioma): Red raised marks.
    • Cavernous Hemangioma: More mature, deeper vascular lesions.

  • Telangiectases:

    • Spider or star angiomas and venous lakes.

  • Purpuric Lesions:

    • Include petechiae, ecchymosis, and purpura from trauma or abuse such as pattern injury or hematomas.

Skin Conditions in Children and Adults

  • Common Pediatric Conditions:

    • Diaper dermatitis.
    • Intertrigo (Candidiasis).
    • Impetigo and atopic dermatitis (eczema).
    • Viral infections such as measles and chickenpox.

  • Malignancies:

    • Basal cell carcinoma, squamous cell carcinoma, and malignant melanoma.

  • Common Adult Conditions:

    • Primary contact dermatitis.
    • Allergic drug reactions and various fungal infections (Tinea).
    • Viral infections including herpes simplex and shingles.

Abnormal Conditions Related to Hair and Nails

  • Hair Conditions:

    • Toxic alopecia, Tinea capitis, traction alopecia, and conditions like seborrheic dermatitis and pediculosis capitis (head lice).

  • Nails Conditions:

    • Paronychia, Beau's lines, splinter hemorrhages, and onychomycosis.
    • Patterns like late clubbing and pitting, as well as habit-tic dystrophy.

Summary Checklist: Skin, Hair, and Nails

  • Inspection:
    • Inspect skin, hair, and nails focusing on color, pigmentation, texture, distribution, shape, contour, and consistency.
  • Palpation:
    • Evaluate skin temperature, texture, presence of edema, mobility, and turgor.
  • Lesions:
    • Document the shape, configuration, and distribution of lesions, teaching patients self-examination techniques.
  • Health Promotion:
    • Encourage regular self-checks and awareness of skin health.