4Integumentary-system

Integumentary System Overview

• Definition: The integumentary system consists of the skin and accessory structures (hair, nails, glands).

• Importance of Dermatology: Medical specialty focusing on disorders of the integumentary system.

Functions of the Skin

• Protection: Shields underlying structures from bacteria, chemicals, and foreign matter.

• Sensory Perception: Relays sensations including pain, temperature, and pressure.

• Fluid Balance: Regulates absorption and evaporation of fluids.

• Temperature Regulation: Manages heat through radiation, conduction, and convection.

• Vitamin Synthesis: Converts substances necessary for vitamin D3 synthesis when exposed to UV light.

• Aesthetics: Enhances beauty and appearance.

Structure of the Skin

• Largest Organ: Covers about 2 square meters and weighs between 4.5-5 kg (7% of body weight).

• Thickness: Ranges from 0.5 to 4 mm; thinnest on eyelids, thickest on heels.

• Layers:

  • Epidermis: Outer layer of epithelial tissue.

  • Dermis: Inner, thicker layer of connective tissue.

  • Subcutaneous Layer: Also known as hypodermis; connects skin to underlying tissues.

Epidermis Composition

• Layers:

  • Stratum Corneum: Outer keratinized layer that protects against water loss and pathogens.

  • Stratum Lucidum: Present only in thick skin (palms/soles); protects against UV rays.

  • Stratum Granulosum: Where keratin starts to accumulate.

  • Stratum Germinativum: Innermost layer; site of cell division and contains melanin-producing cells.

• Cell Types:

  • Keratinocytes: Produce keratin (90% of epidermis).

  • Melanocytes: Produce melanin for UV protection.

  • Langerhans Cells: Involved in immune response.

  • Merkel Cells: Function in touch sensation.

Dermis Characteristics

• Components: Contains collagen and elastic fibers.

• Layers:

  • Papillary Region: Contains dermal papillae, touch receptors, and blood capillaries.

  • Reticular Region: Packed with dense fibers, glands, hair follicles, and adipose cells.

• Skin Conditions: Striae (stretch marks) can form from excessive stretching.

Accessory Structures of the Skin

• Hair: Made of keratin; types include vellus (fine) and terminal (coarse) hair.

  • Hair Follicles: Responsible for hair growth; contain sebaceous glands.

• Nails: Keratinized structures at the tips of fingers and toes; consist of nail body, lunula, and nail root.

• Glands:

  • Sweat Glands: Eccrine (thermal regulation) and apocrine (pheromones).

  • Sebaceous Glands: Produce sebum for skin lubrication.

Skin Aging Effects

• Common Changes:

  • Wrinkling, decreased immune function, dehydration.

  • Thinner skin, decreased sweat production, and hair/nail growth reduction.

Skin Disorders Overview

• Inflammatory/Reactions: Acne, psoriasis, eczema, dermatitis.

• Bacterial Infections: Impetigo, cellulitis, boils.

• Viral Infections: Herpes simplex, herpes zoster (shingles).

• Fungal Infections: Tinea (athlete's foot), candidiasis.

• Parasitic Infections: Scabies, lice.

• Skin Cancer: Melanoma and other forms.

Diagnosis and Treatment

• Clinical Examination: Important for identifying skin lesions and disorders.

• Management: Varies based on the specific condition; may include topical treatments, systemic medications, and lifestyle adjustments.