Membranous Epithelial Tissue

Epithelial Tissue

Membranous Epithelial Tissue

Fundamentals/Characteristics:

Epithelial Characteristics:

• On free surfaces of body cavities/surface of the body
• Tightly packed together & little matrix between
• Remarkable regenerative abilities
• Derived from the trinity of Germ Layers
• Avascular

Added Characteristics:

• ALWAYS one free substance exposed to a body cavity, lumen or skin surface

Function:

• Cover or line surfaces to provide protection

Anatomy:

Anatomy of Cell

• Lumenal side

Contain pojections called microvilli, cilia F:microvilli increase surface area of cell

• Apical side:
• Basal lamina - in close contact with connective tissue
• Gap junctions - water soluble molecules to pass from cytoplasm to cytoplasm of another cell
• Membranous ET Analogy: Houses

Histological Classification:

• 1)Number of layers
  • Simple Membranous ET
  • Stratified
• 2)Shape of cells along exposed surface
  • Squamous - flattened
  • Cuboidal - cube shapped
  • Squamous - flattened
  • Columndar - taller

Types of Membranous Tissues:

• 1)Simple: Single Layer
  • LOC: where diffusion, absorption, filtration and secretion are principal functions
    • Maybe ciliated or microvilli
• 1a)Simple Squamous Epithelium: flattened irregularly shaped cells that are tightly bound, adapted for diffusion and filtration
  • LOC: pulmonary alveoli of lungs
  • Endothelium - lining the inner walls of blood and lymphatic vessels
  • Mesothelium - covers visceral organs and lines body cavities
• 1b)Simple Cuboidal Epithelium: composed of a single layer so f tightly fitted cube shaped cells
  • LOC: lining small duts and tubules
• 1b2)Stratifed Cuboidal Epithelium:
• 1c)Simple Columnar Epithelium: composed of tall columnar cells, height depends on site and function of tissue, nucleus is near basement membrane
• 1d)Simple Ciliated Columnar Epithelium: composed of cilia along its free surface
  • LOC: uterine tubes move egg to uterus
• 1e)Transitional Epithelium:
  • LOC:regions of urinary system
• 1f)Pseudostratifed Ciliated Columnar Epithelium
• 1)Stratified Columnar Epithelum

• 2)Stratified: Multiple layers
• 2a)Stratified Squamous Epithelium Keratinized
  • F: protection

Characteristics:

• contain large amount of keratin
• Constantly lost and replaced
• LOC: SKIN - outer cells dead
• 2b)Stratified Squamous Epithelium Nonkeratinized
• 2c)Stratified Cuboidal
  • Transition Epithelium