TISSUE STUFF

TISSUE TYPES 

  • Tissue 

    • Grouping of cells with a function that make up organs 

    • Ex: muscle, nervous system, connective tissue 

  • Cell 

    • 1 or 2 specific functions 

  • Histology 

    • Study of microscopic cells in tissues 

  • Cells -> tissues -> organ -> system 

 

EPITHELIAL TISSUE 

  • Everywhere 

  • Protection/cover 

  • Secretion 

  • Absorption 

  • Nerves, no blood supply (adjacent) 

  • Cells regen quickly 

  • Many tightly packed cells 

  • SIMPLE SQUAMOUS EPITHELIUM 

    • Simple (single layer of cells) 

    • Allows things to pass through diffusion & filtration, & secretes lubricating substance 

    • Location: air sacs of lungs, blood vessels 

  • SIMPLE CUBOIDAL EPITHELIUM 

    • Secretes & absorbs 

    • Location: kidney tubules 

  • SIMPLE COLUMNAR EPITHELIUM 

    • Absorbs; secretes mucous & enzymes 

    • Location: ciliated tissue of bronchi 

  • PSEUDOSTRATIFIED COLUMNAR EPETHELIUM 

    • Secretes mucus; ciliated tissue moves mucus 

  • STRATIFIED SQUAMOUS EPITHELIUM 

    • Protects against abrasion 

    • Esophagus, mouth, vagina 

  • STRAT. CUBOIDAL EPITHELIUM 

    • Protective tissue 

    • Glands (sweat, salivary, mammary) 

  • STRAT. COLUMNAR EPITHELIUM 

    • Secretes & protects 

    • Male urethra 

  • TRANSITIONAL EPITHELIUM 

    • Allows urinary organs to expand and stretch (bladder, urethra)  

 

Cell Surface Structures 

  • Cilia 

    • Allow things to move on surface (mucus) 

  • Microvilli 

    • Absorption (small intestine) 

 

Junctions 

  • Tight Junction - seals neighbor cells together in epithelial sheet to prevent leakage of molec. Btw. 

  • Adherens Junction - actin bundle in one cell to simple bundle 

  • Desmosome - joins intermediate filaments in one cell to those in a neighbor 

  • Gap junction - allows passage of small-soluble ions & molec. 

  • Hemidesmosome - anchors intermediate filaments in a cell to basal lamina 

 

Glands 

  • Exocrine gland 

    • Chemicals produced 

    • Secreted to lumen 

    • (skin surface) 

  • Endocrine gland 

    • Hormones into blood 

    • Most epithelial 

  • Goblet cell 

    • Unicellular gland 

    • Exocrine gland 

    • Secretes mucus 

 

Connective Tissue 

  • Forms connections btw. Tissues & barriers separating tissues 

  • More matrix & fewer cells 

  • Slower growth & slower healing 

  • Loose v. Dense (compact) 

    • Dense irregular 

      • Unorganized 

      • Good at resisting force from diff directions 

    • Dense regular 

      • Same direction 

      • Resist stretch, pull from certain directions 

    • Loose/areolar 

      • More hollow space 

  • Contractile Tissue 

    • Muscle/can shorten 

    • Lots of cells 

    • Heals more quickly 

    • Skeletal muscle 

      • Attached to skeletal system 

    • Cardiac muscle 

      • heart 

    • Smooth muscle 

      • Everywhere 

  • Nervous Tissue 

    • Brain/spinal cord/peripheral nerves 

    • Neuron & glial cells (support cells) 

    • Carries information through electrical energy 

    • Good blood flow 

    • Poor healing