Skin, Hair, and Nails
Chapter 13: Skin, Hair, and Nails
Structure of the Skin
Largest Organ System: Covers 20 square feet of surface area in adults.
Primary Function: Protects the body from environmental stresses.
Two Main Layers:
Epidermis: Outer, highly differentiated layer.
Basal Cell Layer: Forms new skin cells continually.
Outer Horny Cell Layer: Composed of dead, keratinized cells that are shed.
Dermis: Inner supportive layer.
Connective Tissue (Collagen): Provides strength and resilience.
Elastic Tissue: Allows for flexibility.
Subcutaneous Layer: Located beneath the dermis.
Composed of adipose tissue (fat).
Functions: Stores fat for energy, aids in cushioning/protection, provides increased mobility.
Skin Color
Modified by: Skin thickness and presence of edema.
Determined by: Varying amounts of red, yellow, and brown pigments in all individuals.
Derived from Three Sources:
Melanin: Brown pigment, responsible for darker skin tones and protection against UV radiation.
Carotene: Yellow-orange pigment.
Red-Purple Tones: From the underlying vascular bed.
Hair, Sebaceous Glands, Sweat Glands, and Nails
Hair:
Made of threads of keratin, found in the hair shaft and bulb matrix.
Types: Vellus (fine, soft hair) and Terminal (thicker, darker hair).
Follicle: Undergoes cyclical active and resting phases for hair growth.
Sebaceous Glands:
Secrete sebum, a lipid substance, through hair follicles.
Functions: Lubricate skin and hair, form a protective emulsion.
Sweat Glands:
Eccrine Glands: Produce watery sweat, directly open to the skin surface, primarily for temperature regulation.
Apocrine Glands: Produce a milky secretion, open into hair follicles, primarily in axillae and anogenital areas, become active during puberty.
Nails:
Hard plates of keratin.
Located on the dorsal edges of fingers and toes.
Structure of Nails (Detailed Components)
Nail matrix
Nail bed
Posterior nail fold
Cuticle
Lateral nail fold
Lunula
Nail plate
Functions of the Skin
Protective & Adaptive Properties: Skin is washable, waterproof, and rugged.
Protection: Against trauma, pathogens, and UV radiation.
Prevents Penetration: Acts as a barrier.
Perception: Contains sensory receptors for touch, pain, temperature, and pressure.
Fluid Balance: Prevents excessive water loss from the body.
Temperature Regulation: Through sweating and vasodilation/vasoconstriction.
Identification: Unique skin patterns (e.g., fingerprints) and overall appearance.
Communication: Expresses emotions (e.g., blushing) and health status.
Wound Repair: Ability to regenerate and heal after injury.
Absorption and Excretion: Absorbs some substances (e.g., medications) and excretes waste products (e.g., sweat).
Production of Vitamin D: Synthesizes vitamin D upon exposure to sunlight.
Developmental Competence
Infants, Children, and Adolescents:
Newborn Infants:
Lanugo: Fine, downy hair covering the newborn infant.
Vernix Caseosa: Thick, cheesy substance protecting the fetal skin in utero.
Sebum: Produces milia by holding water in the skin shortly after birth.
Children:
Epidermis thickens, darkens, and becomes lubricated.
Hair growth accelerates.
Adolescents:
Secretions from apocrine sweat glands increase, leading to body odor.
Subcutaneous fat deposits increase.
Development of secondary sex characteristics leads to changes in hair distribution and skin texture.
The Pregnant Woman:
Increased metabolism leads to increased secretion of sweat and sebaceous glands to dissipate heat.
Fat deposits are laid down as maternal reserves for nursing the baby.
Expected skin color changes occur due to increased hormone levels (e.g., linea nigra, chloasma).
The Aging Adult:
Elasticity: Loses elasticity, leading to skinfolds and sags.
Sweat and Sebaceous Glands: Decrease in number and function, resulting in dry skin (xerosis).
Senile Purpura: Discoloration due to increasing capillary fragility.
Skin Breakdown: Cell replacement is slower, and wound healing is delayed due to multiple factors.
Hair Matrix: Functioning melanocytes decrease, leading to gray, fine hair.
Genetics and Environment
Genetic Attributes: Dark-skinned individuals have increased melanin, which affords protection against skin cancer.
Skin Cancer Risk: Increased likelihood of skin cancer in white populations than in Black and Hispanic populations.
Mechanism: Succession of genetic mutations leading to increased chromosome sensitivity to sun damage.
Environmental Risk Factor: Most important is exposure to ultraviolet (UV) radiation from the sun and indoor tanning sources, which changes genetic makeup.
Melanoma Risk: Increased risk for melanoma is related to an increased number of sunburns during one's lifetime.
Ethnic Variations in Skin Presentations:
Keloids.
Hypopigmentation or hyperpigmentation.
Pseudofolliculitis.
Melasma.
Impact of Measles: Highly contagious pathogen with distinct skin manifestations.
Subjective Data: Health History Questions
Past history of skin disease (allergies, hives, psoriasis, eczema).
Change in pigmentation.
Change in mole (size or color).
Excessive dryness or moisture.
Pruritus (itching).
Excessive bruising.
Rash or lesions.
Medications (current and recent).
Hair loss.
Change in nails.
Environmental or occupational hazards.
Patient-centered care (routines, concerns).
Additional History Questions for Infants and Children
Birthmarks?
Change in skin color as a newborn?
Rash or sores?
Diaper rash?
Burns or bruises?
Exposure to contagious or communicable disease?
Habits (e.g., nail biting, hair twisting)?
Steps taken to protect child from sun exposure?
Additional Health History Questions for Adolescents
Skin problems such as pimples, blackheads (acne)?
Additional Health History Questions for Aging Adults
Changes noticed in skin in past few years?
Delay in wound healing?
Other skin pain?
Changes in feet: toenails, bunions, wearing shoes?
Any falls?
History of diabetes or peripheral vascular disease?
Skin care routine?
Objective Data: Physical Examination
Preparation:
Control external variables that impact observed skin color (e.g., lighting).
Focus on being attentive to skin characteristics.
Equipment Needed:
Strong direct lighting, gloves, penlight, small centimeter ruler.
For special procedures: Wood's light (filtered UV light) for fungal infections or pigmentary disorders.
Physical Examination Procedure
Complete Physical Examination: Skin assessment should be integrated throughout the entire examination.
Scrutinize the outer skin surface first before underlying structures.
Separate intertriginous areas (skin folds) such as under large breasts, obese abdomen, and groin, and inspect thoroughly.
Always inspect feet, toenails, and between toes.
Regional Physical Examination: If the patient seeks care solely for skin problems, focus the assessment on the skin.
Overall Impression: Assess skin as one entity to reveal distribution patterns of lesions or color changes.
Inspect and Palpate the Skin
Color:
General pigmentation, freckles, moles, birthmarks.
Widespread color change: Note pallor (pale), erythema (red), cyanosis (blue), or jaundice (yellow).
Determine if color change is transient or due to pathology.
Temperature:
Use the backs of hands to palpate the person.
Skin should be warm and temperature equal bilaterally, suggesting normal circulatory status.
Hands and feet may be slightly cooler in a cool environment.
Note hypothermia (cold) or hyperthermia (hot).
Moisture:
Note diaphoresis (excessive sweating).
Note dehydration (dry mucous membranes, cracked lips).
Texture: Normal skin feels smooth and firm with an even surface.
Thickness: Observe for thickened areas (e.g., callus formation).
Edema: Assess for fluid accumulation in the interstitial space (pitting edema).
Mobility and Turgor: Assess skin elasticity by pinching a fold of skin.
Vascularity or Bruising: Assess for presence of tattoos and/or variations.
Lesions: If present, note:
Color.
Elevation (flat, raised, or pedunculated).
Pattern or shape (grouping or distinctness).
Size (measure in centimeters).
Location and distribution on the body.
Any exudate (note color and odor).
Use a dermatoscope for closer inspection.
Inspect and Palpate Hair
Color: Due to melanin production.
Texture: Characteristics range from fine to thick, curly to straight, and may be affected by hair care products.
Distribution: Review gender patterns of hair distribution (e.g., male pattern baldness, hirsutism).
Lesions: Identify by looking at the scalp and dividing hair into sections.
Inspect and Palpate Nails
Shape and Contour:
Profile Sign: View the index finger at its profile and note the angle of the nail base; it should be approximately 160^ ext{o}. An angle greater than 160^ ext{o} (approaching 180^ ext{o} or more) indicates clubbing.
Consistency: Observe for smooth, regular, not brittle or splitting, and uniform nail thickness.
Color: Translucent nail plate to pink nail bed below. Note ethnic variations.
Capillary Refill: Depress nail edge to blanch for at least 5 seconds and then release, noting the return of color within 1-2 seconds; indicates status of peripheral circulation.
ABCDEF Skin Assessment (Health Promotion)
Teach skin self-examination using the ABCDEF rule to detect suspicious lesions indicative of melanoma.
A: Asymmetry (one half does not match the other half).
B: Border irregularity (edges are ragged, notched, or blurred).
C: Color variations (areas of tan, brown, black, red, white, or blue).
D: Diameter greater than 6 mm (size of a pencil eraser).
E: Elevation or evolution (raised above the surface, or changes in size, shape, color, or symptoms).
F: Funny looking (