Week 5: Overview of Integumentary System

Page 1: Introduction to the Integumentary System

• Overview of the Integumentary System

  • Structure and functions of the integumentary system.

  • Main layers: epidermis, dermis, and subcutaneous (hypodermis) layer.

  • Comparison of thin vs. thick skin in terms of location and function.

  • Study of factors contributing to skin color.

• Components of Skin

  • Includes:

    • Epidermis

    • Dermis

    • Subcutaneous layer

    • Hair

    • Nails

    • Glands (sweat, sebaceous, ceruminous, mammary)

  • Functions:

    • Synthesis of vitamin D

    • Protection of underlying tissues

    • Defense against pathogens

    • Protection against UV radiation

    • Thermoregulation

  • Structure:

    • Three main layers:

      • Epidermis

      • Dermis

      • Subcutaneous (superficial fascia)

Page 2: Functions of Skin

• Protection

  • First line of defense against:

    • Dehydration

    • Injury

    • Microbial invasion

  • Skin characteristics:

    • Dry and slightly acidic (pH: 4-6)

    • Acid mantle protects skin.

    • Antimicrobial peptides limit surface bacteria.

    • Epidermis contains keratin for protection.

    • UV light blocking capabilities.

  • Absorption traits:

    • Transdermal medication absorption

    • Risk of absorbing poisons (e.g., poison ivy).

• Vitamin D Synthesis

  • Skin manufactures Vitamin D via sun exposure, essential for bone health.

Page 3: Sensory Functions and Thermoregulation

• Sense of Touch

  • Largest sensory organ, contains nerve endings for:

    • Touch

    • Temperature

    • Pain

  • Cutaneous sensations include:

    • Tactile

    • Thermal

    • Pain

• Thermoregulation

  • Monitored by thermoreceptors:

    • Blood vessels constrict in cold weather.

    • Blood vessels dilate in warmth, promoting heat loss.

    • Sweat glands aid in cooling via evaporation.

• Nonverbal Communication

  • Expressive facial movements and skin appearance impact self-esteem and emotional well-being.

Page 4: Structure of the Epidermis

• Epidermis Overview

  • Most superficial skin layer: keratinized, stratified squamous epithelium.

  • Avascular, gets blood supply from dermis.

  • Comprised of five different cell types:

    • Keratinocytes

    • Melanocytes

    • Langerhans cells

    • Merkel cells

  • Structure divided into layers, from youngest to oldest:

    • Stratum Basale

    • Stratum Spinosum

    • Stratum Granulosum

    • Stratum Lucidum

    • Stratum Corneum

Page 5: Layers of the Epidermis

• Stratum Basale

  • Deepest layer, contains:

    • Cuboidal cells on basement membrane

    • High concentration of keratinocytes for regeneration

    • Melanocytes for producing melanin.

• Stratum Spinosum

  • Contains keratinocytes producing keratin, stops dividing at this layer.

  • Thickest layer; contains immune cells (Langerhans cells).

• Stratum Granulosum

  • 3-5 layers of keratinocytes with granules of keratin.

  • More prevalent in thick skin.

Page 6: Continued Epidermis and Introduction to Dermis

• Stratum Lucidum

  • Present only in thick skin; clear layer, protective.

• Stratum Corneum

  • Most superficial, ~30 layers of dead keratinized cells, provides waterproof barrier.

• Dermis

  • Lies beneath epidermis; composed of connective and vascular tissue.

  • Contains:

    • Collagen and elastic fibers

    • Blood vessels

    • Nerve endings

    • Glands and hair follicles.

Page 7: Layers and Features of Dermis

• Dermis Composition

  • Includes:

    • Papillary layer: areolar tissue, supplies blood to epidermis.

    • Reticular layer: dense irregular tissue, provides strength and elasticity.

• Sensory Functions

  • Receptors in the dermis detect temperature, pressure, touch, vibration, and pain.

  • Unique epidermal ridges form fingerprints reflecting individual uniqueness.

Page 8: Hypodermis and Skin Color

• Hypodermis Description

  • Subcutaneous layer connecting skin to muscles.

  • Functions:

    • Provides insulation.

    • Acts as fat storage.

    • Vascular with quick absorption of drugs.

• Skin Color

  • Melanin production by melanocytes; influenced by genetics and UV exposure.

  • Types of melanin:

    • Pheomelanin (reddish-brown)

    • Eumelanin (brownish-black).

Page 9: Melanoma and Factors Influencing Skin Color

• Skin Color Factors

  • Hemoglobin- red pigment visible in superficial blood vessels (e.g., lips).

  • Carotene- yellowish-orange pigment from diet affecting skin hue, especially in thick skin.

• Skin Cancer Types

  • Melanoma: aggressive, from melanocytes.

  • Squamous cell carcinoma: from keratinocytes in stratum granulosum.

  • Basal cell carcinoma: the least aggressive skin cancer, from basal cells.

Page 10: Summary of Key Skin Functions and Structures

• Key Facts:

  1. Collagen is the strongest fiber in skin supporting structure and function.

  2. Blood vessels in the dermis supply nutrients to the epidermis.

  3. The papillary layer enhances skin strength.

  4. The reticular layer allows skin stretching.

• Additional Notes:

  • Fingerprints arise from epidermal ridges.

  • Areas rich in carotene appear yellowish-orange.

  • The hypodermis allows for effective administration for medications.