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Epithelial Tissue - OAK PARK USD · PDF file 2012. 9. 28. · Epithelial Tissue Epithelial Tissue Tissues - Introduction ·a group of similar cells specialized to carry on a particular

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  • Epithelial Tissue

    Epithelial Tissue Tissues - Introduction · a group of similar cells specialized to carry on a particular function · tissue = cells + extracellular matrix

    nonliving portion of a tissue that supports cells · 4 types

    epithelial - protection, secretion, absorption connective - support soft body parts and bind

    structures together muscle - movement nervous - conducts impulses used to help control

    and coordinate body activities

    Epithelial Tissues Characteristics · free surface open to the outside or an open internal space (apical surface) · basement membrane anchors epithelium to underlying connective tissue · lack blood vessels · readily divide (ex. skin healing) · tightly packed with little extracellular space

    Epithelial Classifications · classified based on shape and # of cell layers · shape

    squamous - thin, flat cells cuboidal - cube-shaped cells columnar - tall, elongated cells

    · number simple - single layer stratified - 2 or more layers

    Epithelial Locations · cover body surfaces, cover and line internal organs, and compose glands

    skin cells, cells that line the stomach and small intestine, inside your mouth


    cheek cells


    Simple Squamous Epithelium · a single layer of thin, flattened cells

    looks like a fried egg · easily damaged · common at sites of filtration, diffusion, osmosis; cover surfaces · air sacs of the lungs, walls of capillaries, linings of blood and lymph vessels

  • Epithelial Tissue

    Simple Cuboidal Epithelium · single layer of cube-shaped cells

    centrally located nucleus · secretion and absorption · surface of ovaries, linings of kidney tubules, and linings of ducts of certain glands

    Simple Columnar Epithelium · single layer of cells that are longer than they are wide

    nucleus located near basement membrane · ciliated or nonciliated · some have microvilli · goblet cells = secrete mucus · absorption, secretion, protection · linings of uterus, stomach and intestine

    Pseudostratified Columnar Epithelium

    · appear stratified because nuclei are at 2 or more levels

    NOT stratified because all cells touch basement mem. · ciliated · goblet cells (secrete mucus) · protection, secretion, movement of mucus · linings of respiratory system

    Stratified Squamous Epithelium · many layers of flattened cells · named based on appearance of top layer of cells · protection · outer layers of skin, linings of oral cavity, throat, vagina, and anal canal

    Stratified Cuboidal Epithelium · 2 or 3 layers of cuboidal cells · protection · linings of larger ducts or mammary glands sweat glands, salivary glands, and pancreas

    Stratified Columnar Epithelium · protection and secretion · vas deferens, part of the male urethra, parts of the pharynx (throat)

  • Epithelial Tissue

    transitional Epithelium · can stretch · distensibility (stretching), protection · inner lining of urinary bladder and linings of the ureters and part of urethra

    Glandular Epithelium · cells that are specialized to produce and secrete substances into ducts or into body fluids · gland = 1 or more cuboidal or columnar cells · secretion · salivary glands, sweat glands, endocrine glands

    Exocrine vs. Endocrine · exocrine = secrete substances into ducts that open onto surfaces

    skin or linings of digestive tract · endocrine = secrete substances into tissue fluid or blood


    endocrine exocrine

    Exocrine Glands · merocrine = release watery, protein-rich fluid by exocytosis

    salivary glands, sweat glands · apocrine = lose small portions of their cell body during secretion

    mammary glands, ear wax · holocrine = entire cell lyses (breaks apart) during secretion

    sebaceous glands of the skin

    Serous vs. Mucous · serous = typically watery with lots of enzymes

    lubrication · mucous = mucus

    digestive and respiratory systems protection

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