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47 Cards in this Set
- Front
- Back
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Define epithelium and 2 main types
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group of functionally related cells. 1) boundary epithelial- cover lining of body surfaces and cavities 2) glandular- serve as functional group in secretory glands
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functions of epithelial cells
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protection, absorption, transport, secretion from glands, excretion, facilitate diffusion, lubrication
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describe intercellular contacts
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epithelial cells are cohesively attached to each other by adhesion molecules and junctions
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how are nutrients delivered to epithelium?
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by diffusion from blood vessels in adjacent connective tissue since they lack their own blood supply
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what is the basal lamina (basement membrane)?
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A sheet of extracellular matrix to which the epithelial cells are anchored.
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Which surface is apical? Which is basal?
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Surface facing the lumen is apical,other side is basal.
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Which epithelial cells can divide?
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Typically only those attached to basement membrane?
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Name 4 types of cell layering.
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simple
stratified pseudostratified transitional |
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What is the difference between stratified and pseudostratified layers?
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In stratified layers each level is separate and distinct, however in pseudostratified, the cells are all attached to the basement membrane.
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Describe transitional layering.
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a form of stratified epithelium which is highly specialized to accomodate stretching. Found in urinary tract. Has features of both squamous and cuboidal epithelials.
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Name 3 shapes of Epithelial
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cuboidal- cube shaped
squamous-flattened columnar- taller than it is wide |
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What are 3 specializations of the apical epithelial surface?
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Microvilli
Cilia Stereocilia |
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Describe Microvilli
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small projections at the apical surface specialized for absorption. Looks like a short fat comb.
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Describe Cilia
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contains microtubules, has coordinated movements, and is specialized to transport materials.
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Desce Stereocilia
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Non motile, long microvilli, specialized for absorption. Looks like a hair pick.
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Define Zona Occludens
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continuous band that seals the apical surface of one epithelial membrane to another. From side view looks like gum stuck between cells, from top looks like 1920s floor tiles.
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Define Zona Adherens
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continuous bands for the mechanical attachment of cytoskeletal elements (actin)
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Define Macula Adherens (desmosomes)
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Spots of cell adhesions, attachment site of cytoplasmic intermediate filaments (keratins)
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Define Gap Junction
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a communication junction between cells with tiny pores that allow passage of small signaling molecules among cells
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Define integrins
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transmembrane proteins that bind tri-peptide RGD sequence of ECM proteins that is used by epithelial cells to bind components of the basement membrane
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Define E-cadherin
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Transmembrane protein that binds E-cadherin molecules expressed by adjacent cells.
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How are glands derived from epithelial cells?
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exocrine- outgrowth of epithelials that keeps its connection to other epithelials-products released to surface. endocrine-loses connection so product released to blood.
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Describe 2 duct patterns
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Simple- unbranched
compound- branched |
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Exocrine glands have 2 main parts. Name them
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secretory and duct portions
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Name and describe 3 types of secretory compartments
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tubbular- looks like tube
acinar- looks like cluster of grapes tubuloacinar- has tubular and acinar components |
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What's a goblet cell and where are they found?
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modified columnar epithelial cells that make and secrete mucous scattered througout respiratory and intestinal lining
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Name the types of exocrine glands and what they produce.
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Serous- protein product
Mucous- carbohydrate product |
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Describe Merocrine Secretion
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Secretion is exocytosed into lumen
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Describe Apocrine Secretion
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Pinching off of apical cytoplasm with product
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Holocrine Secretion
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Shedding of whole cell.
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What is mesothelium
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Epithelials derived from mesoderm. These simple squamous cells cover external surfaces of digestive organs, lungs and heart
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What are parenchyma?
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functionally specialized cells
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How are epithelials renewed?
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Subject to wear and tear. Only those in contact with basement membrane can be regenerated. Replacement occurs by division of remaining cells. Rapid in intestine, slow in glands
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What are the roles of pseudostratified and stratified epithelial cells?
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pseudo- secretion,transport, sensory reception
stratified- protection simple- secrete, absorb, filter |
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What are regression, metaplasia and neoplasia
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-thinning or loss
-transformation of one tissue type into another -formation of new cell type |
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What is stroma?
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Supportive framework in cells
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What is absorption
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cells taking up materials such as gases, nutrients and sugars
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what is basal lamina composed of?
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type IV collagen, proteoglycans and other extracellular proteins
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DEscribe myoepithelial cells
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Branched epithelial cells with myosin and lots of actin filaments. Specialized for contraction.
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what are hemidesmosomes?
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These are present in a contact zone and bind a epithelial cell to the basal lamina. Hemisdesmosomes are made of integrin proteins.
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What is a cornified layer?
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The top dead layer with no visible cell nuclei.
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What are tonofilaments?
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Keratin bundles that insert into desmosomes.
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What is the basal layer?
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The surface of a cell lying on the basement membrane.
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What are flagella?
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Similar to cilia, found in sperma and limited to one flagellum per cell
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What is the brush border?
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An orderly array of microvilli in lining of absorptive tissues.
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What is keratinized?
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Epithelial cells in which the surface cells are dead with no discernable nuclei
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What is an axoneme?
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The core of cilia and flagella comprised of 9 pairs of microtubules that surround 2 central microtubules.
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