Ch.4 Powerpoint

• Tissue


  Groups of cells with similar structure and function
• Four primary types of tissue

  • Epithelial tissue (epithelium)
  • Connective tissue
  • Muscle tissue
  • Nervous tissue
• Epithelial tissue


  • Cover and line body surfaces
  • Often form sheets with one free surface, the apical surface, and an anchored surface, the basement membrane
  • Avascular (no blood supply)
  • Regenerate easily if well nourished
• Classification of epithelia


  • Number of cell layers: Simple—one layer, Stratified—more than one layer
  • Shape of cells: Squamous—flattened, Cuboidal—cube-shaped, Columnar—shaped like columns

  
• Simple epithelia


  Functions in absorption, secretion, and filtration
• Simple squamous epithelium


  Single layer of flat cells
• Locations of simple squamous epithelium

  • Lines air sacs of the lungs
  • Forms walls of capillaries
  • Forms serous membranes (serosae) that line and cover organs in ventral cavity

  
• Simple cuboidal epithelium


  Single layer of cubelike cells
• Locations of simple cuboidal epithelium

  • Common in glands and their ducts (Salivary glands and Pancreas)
  • Forms walls of kidney tubules
  • Covers the surface of ovaries
• Simple columnar epithelium


  Single layer of tall cells, Goblet cells secrete mucus
• Locations of simple columnar epithelium

  • Lining of the digestive tract from stomach to anus
  • Mucous membranes (mucosae) line body cavities opening to the exterior
• Pseudostratified columnar epithelium


  All cells rest on a basement membrane, Single layer, but some cells are shorter than others giving a false (pseudo) impression of stratification
• Location of pseudostratified columnar epithelium

  • Respiratory tract, where it is ciliated and known as pseudostratified ciliated columnar epithelium

  
• Stratified epithelia


  Consist of two or more cell layers, Function primarily in protection
• Stratified squamous epithelium


  Most common stratified epithelium, Named for cells present at the free (apical) surface, which are squamous

  
• Locations of stratified squamous epithelium


  • Lining of the skin (outer portion), mouth, esophagus

  
• Stratified cuboidal epithelium


  Two layers of cuboidal cells
• Stratified columnar epithelium


  Surface cells are columnar, and cells underneath vary in size and shape

  
• Transitional epithelium


  Composed of modified stratified squamous epithelium, Shape of cells depends upon the amount of stretching, Functions in stretching and the ability to return to normal shape

  
• Location of transitional epithelium

  • Lining of urinary system organs
• Glandular epithelia


  One or more cells responsible for secreting a particular product, Secretions contain protein molecules in an aqueous (water-based) fluid, Secretion is an active process
• Two major gland types develop from epithelial sheets

  • Endocrine glands
  • Exocrine glands
• Endocrine glands


  Ductless; secretions (hormones) diffuse into blood vessels, Examples include thyroid, adrenals, and pituitary
• Exocrine glands


  Secretions empty through ducts to the epithelial surface, Include sweat and oil glands, liver, and pancreas (these are both internal and external types of glands)
• Connective tissue


  • Found everywhere in the body to connect body parts, Includes the most abundant and widely distributed tissues, Functions: Protecting, Supporting, Cushioning, Insulating
• Extracellular matrix


  Nonliving material that surrounds living cells
• Two main elements of the extracellular matrix

  • Ground substance—mostly water, along with adhesion proteins and polysaccharide molecules
  • Fibers: Collagen (white) fibers, Elastic (yellow) fibers, Reticular fibers (a type of collagen)
• Types of connective tissue from most rigid to softest, or most fluid

  • Bone
  • Cartilage
  • Dense connective tissue
  • Loose connective tissue
  • Blood
• Bone (osseous tissue)


  Composed of: Osteocytes (bone cells) sitting in lacunae (cavities), Hard matrix of calcium salts, Large numbers of collagen fibers, Functions to protect and support the body
• Types of cartilage


  • Hyaline cartilage
  • Fibrocartilage
  • Elastic cartilage
• Hyaline cartilage


  Most widespread type of cartilage, Abundant collagen fibers hidden by a glassy, rubbery matrix
• Locations of hyaline cartilage

  • Trachea
  • Attaches ribs to the breastbone
  • Covers ends of long bones
  • Entire fetal skeleton prior to birth
  • Epiphyseal (growth) plates in long bones
• Elastic cartilage


  Provides elasticity, Supports the external ear
• Fibrocartilage


  Highly compressible, Forms cushionlike discs between vertebrae of the spinal column
• Dense connective tissue (dense regular fibrous tissue)

  Main matrix element is collagen fiber, Fibroblasts are cells that make fibers, Locations: Tendons—attach skeletal muscle to bone, Ligaments—attach bone to bone at joints and are more elastic than tendons
• Dense connective tissue (dense irregular fibrous tissue)


  Dermis—lower layers of the skin
• Loose connective tissue


  Softer, have more cells and fewer fibers than other connective tissues (except blood)
• Types of loose connective tissue

  • Areolar
  • Adipose
  • Reticular
• Areolar connective tissue


  Most widely distributed connective tissue, Soft, pliable tissue like "cobwebs", Functions as a universal packing tissue and "glue" to hold organs in place, Layer of areolar tissue called lamina propria underlies all mucous membranes, All fiber types form a loose network, Can soak up excess fluid (causes edema)
• Adipose connective tissue


  An areolar tissue in which adipose (fat) cells dominate, Functions: Insulates the body, Protects some organs, Serves as a site of fuel storage, Locations: Subcutaneous tissue beneath the skin, Protects organs, such as the kidneys, Fat "depots" include hips, breasts, and belly