EPITHELIAL TISSUE

EPITHELIAL TISSUE

1. cover external surfaces, line cavities & hollow organs and form glands

   • protection
   • absorption
   • secretion
   • filtration
   • excretion
   • glands
     • single-celled
       • ENDOCRINE: secrete hormones into interstitial fluid
         • regulates blood sugar
       • EXOCRINE: secretions onto epithelial surface
         • helps aid digestion
           • milk
           • enzymes
           • sebum
     • multi-cellular

2. attaches to the basement membrane

   • has a basal surface
   • has an apical surface
     • cells are exposed to lumen

3. SIMPLE

   • ABSORPTION: nutrients, vitamins, excess liquid
   • SECRETION: mucus, hormones, gastric juices
   • CILIATED: cilia beat in unison to move foreign particles or mucus out
   • NON-CILIATED: cuboidal has microvilli to increase surface area

4. STRATIFIED

   • KERITINIZED: skin
   • NON-KERITANIZED: wet surfaces, mouth, esophagus, epiglottis, pharynx, larynx, tongue
     • against abrasion, water loss, foreign particles, microbes