Integumentary System Overview

Integumentary System Overview

• Composed of the skin (cutaneous membrane) and accessory structures (hair, oil and sweat glands, nails, sensory receptors).
• Largest system in the human body.

Functions

• Provides body protection.
• Regulates body temperature (thermoregulation).
• Synthesizes Vitamin D.
• Supplies sensory information.
• Maintains homeostasis.

Skin Structure

• Skin has two primary layers:
  • Epidermis: Outer layer made of epithelial tissues.
  • Dermis: Inner layer composed of connective tissues.
• Hypodermis: Subcutaneous tissue beneath the dermis, composed of elastic and adipose tissues, not part of the skin.

Epidermis

• Avascular and made of keratinized stratified squamous epithelium.
• Contains four main cell types:
  • Keratinocytes: Produce keratin for protection and hydration prevention.
  • Melanocytes: Produce melanin, affecting skin color.
  • Macrophages (Langerhans cells): Involved in immune responses.
  • Tactile epithelial cells (Merkel cells): Responsible for touch sensation.
• Comprised of 4-5 layers:
  • Stratum corneum: Most superficial layer.
  • Stratum lucidum: Present only in thick skin.
  • Stratum granulosum: Keratinocytes undergoing apoptosis.
  • Stratum spinosum: Provides strength and flexibility.
  • Stratum basal: Deepest layer with stem cells and melanocytes.

Dermis

• Contains blood vessels, nerves, glands, hair follicles, and extracellular matrix.
• Divided into two layers:
  • Papillary layer: Thin, rich in nerve endings.
  • Reticular layer: Thick, contains collagen fibers for resistance to stretching.

Skin Color

• Determined by three pigments: melanin, hemoglobin, and carotene.
• Skin tone variation is due to differences in pigment amount, not melanocyte count.
• Increased melanin production occurs with UV exposure.

Accessory Structures

• Includes hair, hair follicles, sebaceous glands, sweat glands, and nails.

Hair

• Composed of dead, keratinized cells.
• Functions include protection, insulation, and sensitivity to touch.
• Contains two main parts: hair shaft (above skin) and follicle (below skin).

Glands

• Sebaceous glands: Connected to hair follicles and secrete sebum (prevents drying and bacterial growth).
• Eccrine sweat glands: Most numerous, open directly on skin, beginning function after birth.
• Apocrine sweat glands: Located mainly in hairy skin, activated at puberty.
• Ceruminous glands: Modified sweat glands in the ear canal producing earwax.

Nails

• Hard, keratinized epidermal cells forming protective coverings over digits.
• Structures include free edge, nail body (with lunula), and nail root.

Sensory Receptors

• Superficial receptors: Merkel and Meissner receptors (sensitive to light touch).
• Deep receptors: Pacinian corpuscles and Ruffini receptors (sensitive to vibration).

Skin Types

• Thin skin: All body parts except palms and soles, no stratum lucidum.
• Thick skin: Found on palms and soles, has stratum lucidum, fewer sebaceous glands but more sweat glands.

Wound Healing

• Epidermal wound healing: For superficial wounds affecting only the epidermis.
• Deep wound healing: For injuries extending into the dermis and subcutaneous layers.

Development

• Epidermis originating from ectoderm, while the dermis develops from mesoderm.

Aging

• Changes include the development of wrinkles, dehydration, reduced sweat production, gray hair due to decreased melanocytes, and overall decrease in skin thickness.
• Increased vulnerability to pressure ulcers.

Skin Cancer

• Major cause: Excess UV exposure.
• Three main types:
  • Basal cell carcinoma.
  • Squamous cell carcinoma.
  • Malignant melanoma.

Burns

• Damage from heat, electricity, radioactivity, or chemicals, classified by severity.
  • First-degree burn: Only the epidermis (e.g., sunburn).
  • Second-degree burn: Destroys epidermis and part of dermis (e.g., blister).
  • Third-degree burn: Full-thickness burn affecting all skin layers.
• The rule of nines helps estimate burned surface area in adults.

Explore the key aspects of the integumentary system, which includes the skin and its accessory structures. This quiz covers the structure, functions, and layers of the skin, including details about the epidermis and dermis. Test your knowledge about how this essential system protects the body and regulates various functions.