Skin Structure and Functions

Skin Structure

• The skin is composed of three main layers:
  • Epidermis (outermost layer): keratinocytes, melanocytes, Langerhans cells, and Merkel cells
  • Dermis (middle layer): collagen, elastin, blood vessels, nerve endings, and hair follicles
  • Hypodermis (innermost layer): subcutaneous fat, connective tissue, and blood vessels

Skin Functions

• Barrier function: protects the body from external factors (water, temperature, pathogens)
• Regulatory function: regulates body temperature, water loss, and electrolyte balance
• Immune function: detects and responds to pathogens and foreign substances
• Sensory function: detects and responds to sensations (touch, pressure, pain, temperature)

Skin Lesions

• Primary lesions:
  • Macule: flat, discolored area
  • Papule: small, raised area
  • Plaque: flat, raised area
  • Nodule: large, raised area
  • Vesicle: small, fluid-filled blister
  • Bulla: large, fluid-filled blister
• Secondary lesions:
  • Scale: dry, flaky skin
  • Crust: dried serum, pus, or blood
  • Erosion: loss of epidermis
  • Ulcer: loss of epidermis and dermis

Skin Exam

• Inspection: visual examination of the skin
• Palpation: examination of the skin by touch
• Auscultation: examination of the skin using a stethoscope (rarely used)

Common Dermatological Conditions

• Acne: inflammatory condition characterized by comedones, papules, and pustules
• Eczema: inflammatory condition characterized by itching, redness, and dryness
• Psoriasis: chronic condition characterized by scaly, red plaques
• Skin Cancer: malignant growth of skin cells (melanoma, basal cell carcinoma, squamous cell carcinoma)

Dermatological Terminology

• Erythema: redness of the skin
• Pruritus: itching
• Urticaria: hives
• Hyperpigmentation: increased skin pigmentation
• Hypopigmentation: decreased skin pigmentation

Skin Structure

• The skin is composed of three main layers: epidermis, dermis, and hypodermis.
• The epidermis is the outermost layer, containing keratinocytes, melanocytes, Langerhans cells, and Merkel cells.
• The dermis is the middle layer, comprising collagen, elastin, blood vessels, nerve endings, and hair follicles.
• The hypodermis is the innermost layer, consisting of subcutaneous fat, connective tissue, and blood vessels.

Skin Functions

• The skin serves as a barrier against external factors such as water, temperature, and pathogens.
• It regulates body temperature, water loss, and electrolyte balance.
• The skin has immune functions, detecting and responding to pathogens and foreign substances.
• It also has sensory functions, detecting and responding to sensations like touch, pressure, pain, and temperature.

Skin Lesions

• Primary lesions include macules, papules, plaques, nodules, vesicles, and bullae.
• Macules are flat, discolored areas, while papules are small, raised areas.
• Plaques are flat, raised areas, and nodules are large, raised areas.
• Vesicles are small, fluid-filled blisters, and bullae are large, fluid-filled blisters.
• Secondary lesions include scales, crusts, erosions, and ulcers.
• Scales are dry, flaky skin, while crusts are dried serum, pus, or blood.
• Erosions involve the loss of epidermis, and ulcers involve the loss of both epidermis and dermis.

Skin Exam

• The skin exam involves three main techniques: inspection, palpation, and auscultation.
• Inspection is a visual examination of the skin.
• Palpation is an examination of the skin by touch.
• Auscultation is an examination of the skin using a stethoscope, though it is rarely used.

Common Dermatological Conditions

• Acne is an inflammatory condition characterized by comedones, papules, and pustules.
• Eczema is an inflammatory condition characterized by itching, redness, and dryness.
• Psoriasis is a chronic condition characterized by scaly, red plaques.
• Skin cancer includes malignant growth of skin cells, such as melanoma, basal cell carcinoma, and squamous cell carcinoma.

Dermatological Terminology

• Erythema refers to redness of the skin.
• Pruritus refers to itching.
• Urticaria refers to hives.
• Hyperpigmentation refers to increased skin pigmentation.
• Hypopigmentation refers to decreased skin pigmentation.