Integumentary System Functions and Structure

Integumentary System Functions

• The integumentary system (skin) provides multiple protective functions:
  • Protection against abrasion and ultraviolet light.
  • Prevention of microorganisms from entering the body.
  • Reduces water loss, preventing dehydration.
• Sensory receptors in the skin detect heat, cold, touch, pressure, and pain.
• The skin produces a molecule that can be transformed into vitamin D when exposed to ultraviolet light, which is important for calcium homeostasis.
• Temperature regulation: The skin plays a critical role in maintaining body temperature.
  • Constriction of dermal blood vessels reduces heat loss when the body is cold.
  • Dilation of blood vessels and sweating helps cool the body down when it is hot.

Skin Structure

• The skin is made of two main layers:
  • Epidermis:
    • The outermost layer, composed of keratinized stratified squamous epithelium.
    • Prevents water loss and resists abrasion.
    • Keratinization is the process where cells become filled with the protein keratin, making them hard and forming a permeability barrier.
    • Consists of five layers, from deep to superficial:
      • Stratum basale: The deepest layer where mitotic cell division occurs.
      • Stratum spinosum: Consists of 8-10 layers of cells that appear to have thorn-like spikes.
      • Stratum granulosum: A layer of cells that produce keratin granules.
      • Stratum lucidum: A clear layer found only in thick skin (palms and soles).
      • Stratum corneum: The outermost, dead layer of cells that forms a barrier against abrasion and prevents water loss.
  • Dermis:
    • The deeper layer of skin, made of dense connective tissue.
    • Contains blood vessels, nerves, hair follicles, sweat glands, and sebaceous glands.
    • Dermal papillae are projections that extend into the epidermis.
    • Hypodermis: A layer of loose connective tissue and adipose tissue, containing about half of the body’s stored lipids. It attaches the skin to underlying bone and muscle.

Skin Appendages

• Hair:
  • Hair follicles are invaginations of the epidermis that extend into the dermis.
  • The hair shaft protrudes above the skin's surface.
• Sebaceous glands:
  • Secrete oil (sebum).
  • Simple, branched acinar glands connected to hair follicles.
  • Sebum lubricates hair and skin, preventing drying and protecting against bacteria.
• Eccrine sweat glands:
  • Secrete water-based sweat.
  • Simple, coiled, tubular glands found almost everywhere on the skin, most numerous in palms and soles.
  • They release sweat by merocrine secretion.

Skin Diseases

• Eczema:
  • An allergic reaction that manifests as dry, itchy patches of skin resembling rashes.
  • Can be accompanied by swelling, flaking, and, in severe cases, bleeding.
  • Often associated with dust mite allergies.
• Acne:
  • Results from infection by acne-causing bacteria (Propionibacterium and Staphylococcus).
  • Can lead to redness and potential scarring.
• Malignant melanoma:
  • A rare form of skin cancer arising from melanocytes.
  • Can appear as a large, flat lesion or a deeply pigmented nodule.
  • Can be life-threatening if left untreated.

Aging and the Integument

• Decreased blood flow and skin thinning: Due to a decrease in collagen production.
• Decreased activity of sebaceous and sweat glands: Makes temperature regulation more difficult.
• Loss of elastic fibers: Causes sagging and wrinkles.

Explore the essential functions and structure of the integumentary system in this quiz. Understand how the skin protects the body, regulates temperature, and plays a role in vitamin D production. Test your knowledge on the layers of the skin and their significance.