Integumentary System – Skin, Hair & Nails (Chapter 13)

Integumentary System Overview

• Chapter 13 focus: Skin, hair, nails = the integumentary system (largest organ)
• Two principal skin layers
  • Epidermis (outer, avascular)
  • Dermis (inner, vascular, connective tissue, glands)
  • Beneath dermis: subcutaneous adipose tissue

Anatomy of Hair

• Shaft: visible portion above skin
• Root & bulb matrix: below surface, site of growth
• Growth cycle: active phase ⇄ resting phase
• Arrector pili ("erector peeli") muscles cause goose-bumps by contracting
• Hair types
  • Vellus: fine, faint body covering
  • Terminal: darker/thicker; scalp, eyebrows/lashes, axilla, pubic, face, chest

Anatomy of Nails

• Hard, clear keratin plates with longitudinal ridges
• Pink coloration from underlying capillary bed
• Normal nail-bed angle ≈ 160^{\circ} (clubbing > 180^{\circ})

Cutaneous Glands

• Sebaceous (oil) glands
  • Secrete sebum through follicles → lubrication, water-resistant emulsion
  • Absent on palms/soles; most numerous on scalp, face, chin → acne sites
• Eccrine (sweat) glands
  • Open directly to skin; activated ≥ 2 months of age; crucial for thermoregulation
• Apocrine glands
  • Open into hair follicles; milky secretion → musky body odor (axilla, anogenital, nipples, navel)

Functions of Skin

• Protection: barrier vs. pathogens, chemicals, trauma, UV
• Prevents penetration/ fluid loss
• Perception: pain, temperature, touch → neurosensory feedback
• Temperature regulation: vasoconstriction/dilation, sweat, shiver
• Identification & communication (blushing, pallor)
• Wound repair (cell renewal)
• Absorption & excretion (sweat, some meds)
• Vitamin D synthesis (UV → cholesterol precursors)

Aging & Skin Changes

• ↓ Elastsin / collagen / subcutaneous fat / muscle → thin "tissue-paper" skin, sagging
• ↓ Sweat & sebaceous glands → dry skin, ↑ heat-stroke risk
• Senile purpura: purple bruises from fragile vasculature
• Slower cell replacement → delayed healing
• Hair: ↓ melanin → graying (20s–30s possible), patterned alopecia (receding "W" hairline)
• Hormone shifts: ↓ testosterone → less axillary/pubic hair; ↓ estrogen (women) → facial bristles
• Nails: slower growth; dull, longitudinal ridges
• Psychosocial: anxiety about wrinkles/appearance

Cultural & Genetic Considerations

• Skin cancer risk highest in non-Hispanic Whites; lower in Blacks, Native Americans, Asians due to melanin protection
• UV exposure (sun/tanning beds) = Most dangerous modifiable risk factor; cumulative sunburns ↑ risk
• Genetic UV impact: DNA damage → oncogene mutation → tumor-suppressor gene alteration

Common Black-skin variations

• Keloids (excess scar tissue)
• Hypo/Hyper-pigmentation patches
• Pseudofolliculitis (razor bumps)
• Melasma ("mask of pregnancy") possible in any ethnicity
• Elliptical hair shaft → traction alopecia susceptibility

Skin Cancer Risk Factors

• Personal/family history
• > 50 moles
• Light skin, blond/red hair, freckles, burns easily
• High UV exposure (occupation, recreation, tanning beds)
• Age ↑

Health-History Interview Guide (pp. 202–206)

• Past skin diseases (eczema, psoriasis, allergies, hives)
• Change in pigmentation (generalized vs. localized)
• Moles: ABCDEF rule (see below)
• Excess dryness (xerosis) or oiliness (seborrhea)
• Pruritus (itching): onset, migration, triggers
• Bruising: location, frequency (falls? abuse?)
• Rash/lesions timeline & spread
• Medications (photosensitivity, rashes)
• Hair loss (alopecia) or hirsutism (excess hair)
• Nail changes (color, shape, brittleness)
• Environmental/occupational hazards (farmers, sailors, pesticides, coal, creosote)
• Self-care behaviors & sun protection
• Additional aging-adult questions: delayed wound healing, foot care, skin pain, frequent falls, diabetes/PVD history

Key Definitions

• Pallor = paleness; anemia, shock
• Erythema = redness; inflammation, fever
• Cyanosis = blue/mottled; hypoxemia
• Jaundice = yellow; ↑ bilirubin (liver, gallbladder)
• Seborrhea = oily skin/scalp
• Xerosis = dry skin
• Pruritus = itching

Physical Examination Technique

Preparation & Equipment

• Good lighting (natural ideal), penlight, ruler (cm/mm), gloves, warm room, warm hands
  Inspection Strategy
• Integrate head-to-toe; begin with hands (hand-shake) then expose sequentially; inspect intertriginous folds; remove socks for feet assessment (esp. diabetics); stand patient then overview entire surface
  Palpation
• Temperature: dorsal hand surface; compare bilaterally
• Moisture: dry/diaphoretic/clammy
• Texture: smooth, firm
• Thickness: uniform except palms/soles
• Mobility & turgor: pinch clavicle → instant recoil; tenting = dehydration
• Edema: press 3–4 sec → pit depth grade (1+ mild to 4+ severe)

Skin Color Findings & Sites to Check

• Pallor best seen in mucous membranes, conjunctiva, nail beds
• Cyanosis best in lips, nose, cheeks, ears, oral mucosa; artificial light better than sun
• Jaundice: junction of hard/soft palate & sclera; differentiate from callus/yellow palms (carotenemia) or turmeric intake

Lesion Assessment Framework

ABCDE + F acronym

• A = Asymmetry
• B = Border irregularity
• C = Color variation
• D = Diameter > 6\,\text{mm} (≈ pencil eraser)
• E = Elevation / Evolution (change)
• F = Funny feeling (subjective change: itching, tingling)

Detailed Description Checklist (Table 13-2 → 13-4)

• Color, elevation, pattern/shape, size (use ruler; avoid "dime-sized"), anatomic location, distribution (localized vs. generalized, intertriginous, sun-exposed), exudate (color, odor)

Lesion Shapes/Configurations

• Annular (ring, e.g., tinea corporis)
• Confluent (run together)
• Linear (scratch)
• Zosteriform (dermatomal line; shingles)
• Grouped (cluster)
• Target/Bulls-eye (erythema migrans—Lyme)
• Gyrate (coiled; scabies burrow)

Primary Lesions (on previously normal skin)

• Macule (<1 cm flat; e.g., freckle)
• Patch (>1 cm macule)
• Papule (<1 cm elevated; wart)
• Plaque (>1 cm papule coalesced; psoriasis)
• Nodule (solid, deep; fibroma)
• Tumor (>few cm, firm/soft)
• Wheal (transient, irregular, edematous; mosquito bite)
• Urticaria (confluent wheals, hives)
• Vesicle (<1 cm fluid; chickenpox)
• Bulla (>1 cm vesicle; friction blister)
• Cyst (encapsulated, fluid-filled, dermis/subQ)
• Pustule (purulent; acne, impetigo)

Secondary Lesions (changes over time)

• Crust (scab)
• Scale (flakes; psoriasis, dry skin)
• Fissure (linear crack; athlete’s heel, cheilosis)
• Erosion (shallow scooped depression)
• Ulcer (deeper into dermis; pressure injury)
• Excoriation (self-inflicted scratch)
• Scar; Atrophic scar (striae)
• Lichenification (prolonged scratching → thickened)
• Keloid (hypertrophic scar, common in Blacks)

Vascular & Misc.

• Cherry angioma: 1\text{–}5\,\text{mm} bright red papule, trunk >30 yrs
• Senile purpura: purple ecchymoses elderly
• Contusion stages (blue→purple→green→yellow)

Pressure Injuries (formerly ulcers)

Stage 1 – intact skin; non-blanchable erythema
Stage 2 – partial-thickness loss: open pink/red wound bed or intact serum-filled blister (quiz answer emphasized)
Stage 3 – full-thickness; extends into subcutaneous fat; visible granulation, possible slough
Stage 4 – full-thickness; exposes muscle/bone/tendon; slough, eschar, rolled edges, tunneling
Prevention pearls

• Reposition q 2 h; use draw-sheet (avoid shear)
• Assess on admission/document to avoid hospital-acquired liability
• Negative-pressure wound therapy ("wound vac") promotes healing

Hair & Scalp Assessment

• Color, distribution, quantity
• Texture: fine/coarse; shiny indicates good nutrition
• Alopecia types: toxic (chemo), traction (tight braids), androgenic (male pattern)
• Hirsutism: excess terminal hair in women (endocrine disorder, meds)
• Scalp lesions: dandruff, lice (check occipital/post-auricular areas), sebaceous cysts

Nail Assessment

• Shape/angle \approx160^{\circ}
• Clubbing: angle > 180^{\circ}, spongy; indicates chronic hypoxia
• Color: pink (blanch test/cap refill \le2\,\text{s}; >3\,\text{s} = sluggish)
• Surface: smooth vs. ridges
  • Beau’s lines: transverse depression → transient growth arrest (illness)
  • Splinter hemorrhages: linear red-brown; infective endocarditis, trauma
  • Onychomycosis: yellow-green fungal thickening (common with artificial nails)

Temperature, Moisture, Turgor Quick Guide

• Hypothermia: generalized (shock) or localized (limb cast/vasc. insuff.)
• Hyperthermia: fever, exercise, infection
• Moisture spectrum: dry → moist → diaphoresis (profuse)
• Dehydration signs: dry mucosa, dull lips/tongue, longitudinal furrows

Malignant Skin Lesions

Basal Cell Carcinoma (most common, least aggressive)

• Sun-exposed head/neck; pearly pink papule, possible ulcer
  Squamous Cell Carcinoma
• Hands/head; red scaly patch → central ulcer; grows faster
  Malignant Melanoma (most deadly)
• Often arises from nevus; irregular border, multicolor (brown/black/tan/blue), >6\,\text{mm}, rapid change

Patient Education & Self-Care

• Monthly head-to-toe self-exam: full-length + hand mirror (inc. soles, between toes, back, scalp)
• Annual dermatology visit if numerous moles or risk factors
• Sun protection: SPF ≥30, reapply q 2 h, wide-brim hats, UPF clothing; avoid tanning beds
• Avoid occupational exposure (chemicals, coal, creosote) or use PPE
• Diabetic foot care: inspect daily w/ mirror, keep nails straight across, no barefoot walking
• Hydration & emollients for elderly dry skin; gentle cleansing + thorough drying of intertriginous areas

Ethical / Practical Implications

• Skin assessment crucial for abuse detection (unexplained bruises above knees/elbows)
• Documentation accuracy: describe lesions precisely, note tattoos & existing wounds to protect patient & facility (legal)
• Cultural sensitivity: recognize normal variations (e.g., hyperpigmented palms in darker skin) to avoid misdiagnosis

Numerical / Measurement Quick List

• 6\,\text{mm} diameter = critical melanoma threshold
• Nail-bed angle: normal \approx160^{\circ}, clubbing >180^{\circ}
• Capillary refill normal 1\text{–}2\,\text{s} (press 5 s then release)
• Cherry angioma size 1\text{–}5\,\text{mm}

Exam & Quiz Hints Mentioned in Lecture

• Pressure injury stage 2 was explicitly given as quiz answer
• "Nurse hat" picture may appear on test (know skin categories table pp 226–228)
• Diabetic patients must "inspect their feet every day"—likely test item
• ABCDEF criteria & lesion shapes expect exam representation (annular, linear, target, zosteriform)

Key Vocabulary Round-Up

• Arrector pili, vellus/terminal hair, seborrhea, xerosis, pruritus, excoriation, lichenification, senile purpura, traction alopecia, erythema migrans, cheilosis, wound vac, eschar, slough

"If It Wasn’t Hard, Everyone Would Do It" (Motivational Close)

• Mastery requires: meticulous observation, precise description, cultural awareness, patient teaching, and relentless documentation.