JR

APHY101 - Epithelial & Connective Tissues (Lecture Notes)

Epithelial Tissues: Key Concepts

  • Epithelial tissues: tightly packed cells with an apical (free) surface and a basement membrane; avascular; classified by number of cell layers and cell shape.
  • Connective tissues: cells spaced apart with an extracellular matrix; matrix ranges from fluid to solid; generally good blood supply; highly vascularized.

Epithelial Tissue Types (Table 5.3)

  • Simple squamous epithelium
    • Description: Single layer, flattened cells
    • Function: Filtration, diffusion, osmosis; covers surfaces
    • Location: Air sacs of lungs; walls of capillaries; linings of blood and lymph vessels; membranes lining body cavities and covering viscera
  • Simple cuboidal epithelium
    • Description: Single layer, cube-shaped cells
    • Function: Protection, secretion, absorption
    • Location: Surface of ovaries; linings of kidney tubules; linings of ducts of certain glands
  • Simple columnar epithelium
    • Description: Single layer, elongated cells
    • Function: Protection, secretion, absorption
    • Location: Linings of uterus, stomach, and intestines
  • Pseudostratified columnar epithelium
    • Description: Single layer, elongated cells
    • Function: Protection, secretion, movement of mucus and substances
    • Location: Linings of respiratory passages
  • Stratified squamous epithelium
    • Description: Many layers, top cells flattened
    • Function: Protection
    • Location: Superficial layer of skin; linings of oral cavity, vagina, and anal canal
  • Stratified cuboidal epithelium
    • Description: 2 or 3 layers, cube-shaped cells
    • Function: Protection
    • Location: Linings of ducts of mammary glands, sweat glands, salivary glands, and pancreas
  • Stratified columnar epithelium
    • Description: Top layer of elongated cells, lower layers of cube-shaped cells
    • Function: Protection, secretion
    • Location: Part of the male urethra and lining of larger ducts of excretory glands
  • Transitional epithelium
    • Description: Many layers of cube-shaped and elongated cells
    • Function: Stretchability, protection
    • Location: Inner lining of urinary bladder and linings of ureters and part of urethra

Connective Tissues: Key Concepts

  • Cells are spaced apart with extracellular matrix between cells; matrix varies from fluid to solid; generally good blood supply.

Connective Tissues (Table 5.7)

  • Connective Tissue Proper
    • Areolar connective tissue
    • Matrix: Cells in fluid-gel matrix
    • Function: Binds organs
    • Location: Beneath the skin, between muscles, beneath epithelial tissues
    • Adipose tissue
    • Function: Protects, insulates, stores fat
    • Location: Beneath the skin, around the kidneys, behind the eyeballs, on the surface of the heart
    • Reticular connective tissue
    • Function: Supports
    • Location: Walls of liver and spleen
    • Dense regular connective tissue
    • Function: Binds body parts
    • Location: Tendons, ligaments
    • Dense irregular connective tissue
    • Function: Sustains tissue tension
    • Location: In the deep layer of skin
    • Elastic connective tissue
    • Function: Provides elastic quality
    • Location: Connecting parts of the spinal column, in walls of arteries and airways
  • Specialized Connective Tissue
    • Hyaline cartilage
    • Matrix: Cells in solid-gel matrix
    • Function: Supports, protects, provides framework
    • Location: Ends of bones, nose, and rings in walls of respiratory passages
    • Elastic cartilage
    • Function: Supports, protects, provides flexible framework
    • Location: Framework of external ear and part of larynx
    • Fibrocartilage
    • Function: Supports, protects, absorbs shock
    • Location: Between bony parts of spinal column, parts of pelvic girdle, and knee
    • Bone
    • Matrix: Cells in solid matrix
    • Function: Supports, protects, provides framework
    • Location: Bones of skeleton, middle ear
    • Blood
    • Matrix: Cells and platelets in fluid matrix
    • Function: Transports gases, defends against disease, clotting
    • Location: Throughout the body in a closed system of blood vessels and heart chambers

Quick Reference: Epithelial vs Connective Tissues

  • Epithelial tissues: cover surfaces, line cavities and glands; have apical surface and basement membrane; avascular; classified by layer number and cell shape.
  • Connective tissues: support, connect, protect; have extensive extracellular matrix; vascularity varies; includes bone, cartilage, adipose, blood, etc.