AS111 Integument A&P (1) powerpoint

Integumentary System Overview

  • The integumentary system consists of the skin and its accessory organs.
  • Key components:
    • Skin
    • Constitutes approximately 6% of body weight.
    • The body's single largest organ.
    • Accessory organs include:
    • Nails (can include horns and hooves)
    • Hair
    • Glands

Skin Layer Structure

  • There are three main skin layers:
    • Epidermis
    • Outermost layer of the skin.
    • Avascular, meaning it does not contain blood vessels.
    • Dermis
    • The layer below the epidermis.
    • Contains:
      • Blood vessels
      • Lymph vessels
      • Nerve fibers
      • Accessory organs
    • Hypodermis
    • Also known as the subcutaneous layer.
    • Composed of connective tissue, primarily fat.

Detailed Structure of the Epidermis

  • Epidermal Layers consist of:
    • Stratum Corneum
    • Superficial layer.
    • Stratum Lucidum
    • Clear layer, found only in thick skin.
    • Stratum Granulosum
    • Granular layer.
    • Stratum Spinosum
    • Spinous layer.
    • Stratum Germinativum (or Basal Layer)
    • Deepest layer where cell division occurs.
  • In animals with hair, the haired areas only have three layers:
    1. Stratum Corneum
    2. Stratum Granulosum
    3. Stratum Germinativum

Epidermal Cell Types

  • Three distinct types of epidermal cells:
    • Keratinocytes
    • Function: Produce keratin, which is a key structural protein in the skin.
    • Melanocytes
    • Function: Produce pigment (melanin).
    • Stimulated by Melanocyte Stimulating Hormone (MSH).
    • Medical Conditions:
      • Albinism - lack of melanin.
      • Melanism - excess melanin.
    • Langerhans Cells
    • Function: Play a role in immunity by being phagocytic and carrying antigens to T cells.

Modified Epidermal Structures

  • Structures include:
    • Hair
    • Horns, Hooves
    • Chestnuts and Ergots
    • Keratinization (or Cornification)
    • Definition: The process of drying and hardening of the superficial cells due to high levels of keratin.

Epithelial Tissue

  • The integument is made up of epithelial tissue that is:
    • Stratified (layered)
    • Squamous (flattened epithelium)
  • Types of epithelial tissue in the integument:
    • Keratinized
    • Found in the epidermis and superficial layers of the skin.
    • Non-Keratinized
    • Found in areas like the mouth, esophagus, vagina, and rectum.

Specific Modified Epidermal Structures

  • Horns
    • Permanent outgrowths of the frontal skull bone with a bony core and a keratin sheath.
  • Antlers
    • Temporary outgrowths of the frontal skull bone with a bony core and shed skin.
    • Both structures originate from keratinized epithelium.
  • Polled
    • Term for animals that are naturally hornless.
  • De-Horning
    • A process usually conducted at a young age and is