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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

    intestines

    cheek cells

    skin

    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

    hormones

    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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