integumentary hw 3

Integumentary System Structures

  • Main Structures:
    • Skin
    • Hair
    • Nails
    • Glands

Functions of the Skin

  • Resistance to trauma, infection, and water
  • Vitamin D synthesis
  • Sensation
  • Thermoregulation
  • Nonverbal communication

Types of Skin

Thick Skin

  • Strata: 5 (from deep to superficial)
    • stratum basale
    • stratum spinosum
    • stratum granulosum
    • stratum lucidum
    • stratum corneum
  • Location: Soles of feet and palms of hands

Thin Skin

  • Strata: 4 (missing stratum lucidum)
    • stratum basale
    • stratum spinosum
    • stratum granulosum
    • stratum corneum
  • Location: Covers most of the body

Epidermal Cell Types

  • Stem Cells: Located in stratum basale; give rise to keratinocytes.
  • Keratinocytes: Located in all layers; produce keratin.
  • Melanocytes: Located in stratum basale; produce melanin.
  • Tactile Cells: Located in stratum basale; function in sensation.
  • Dendritic Cells: Located in stratum spinosum & granulosum; immune response.

Epidermal Strata Description

  • Stratum Basale:

    • Single layer of stem cells/keratinocytes.
    • Contains melanocytes and tactile cells.

  • Stratum Spinosum:

    • Several layers of keratinocytes, thickest in thin skin.
    • Contains dendritic cells; gives spiny appearance due to desmosomes.

  • Stratum Granulosum:

    • 3-5 layers of flat keratinocytes.
    • Keratohyalin granules present; gives grainy appearance.

  • Stratum Lucidum:

    • Thin, clear zone; present only in thick skin.
    • Densely packed keratinocytes.

  • Stratum Corneum:

    • Approximately 30 layers of dead, keratinized cells.
    • Durable surface layer, resistant to abrasion.

Dermis Layers

  • Papillary Layer:

    • 20% of dermis; made of areolar connective tissue.
    • Contains dermal papillae; rich in blood vessels and sensory receptors.

  • Reticular Layer:

    • Dense irregular connective tissue; larger blood vessels and nerves.
    • Provides support; contains adipocytes.

Hypodermis

  • Tissues: Adipose and some areolar/elastic tissue.
  • Functions: Stabilizes skin, stores energy, absorbs pressure.

Skin Coloration Alterations

  • Cyanosis: Bluish tint due to low oxygenation.
  • Jaundice: Yellowing due to high bilirubin levels.
  • Albinism: Lack of melanin; genetic condition.

Types of Exocrine Glands

  • Holocrine Glands: Sebaceous glands; secrete via cell breakdown.
  • Apocrine Glands: Sweat glands; secrete via large lumen.
  • Merocrine Glands: Eccrine sweat glands; secrete via small ducts.

Burns Classification

  • First-degree Burn:

    • Affects only epidermis; partial-thickness; heals in days.

  • Second-degree Burn:

    • Affects epidermis and part of dermis; partial-thickness; may leave scars.

  • Third-degree Burn:

    • Affects all layers; full-thickness; often requires skin grafts; can be fatal.