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66 Cards in this Set
- Front
- Back
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What does epithelial tissue develop from?
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All three embryonic germ layers
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What distinguishes ET from connective tissue?
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-CT has very few cells with abundent extracell. matrix
-ET is entirely cellular and the basal lamina is its only CT |
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3 functions of ET:
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1. Surface covering
2. Absorption 3. Secretion |
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3 characteristics of ET:
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-Polarized
-Avascular -Basal lamina |
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How are epithelial cells polarized?
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Have three sides:
-Apical -Basal -Lateral |
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If epithelial cells are avascular how do they get nutrients?
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Diffusion
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What is the basal lamina?
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The basement membrane - the basal layer of Epithelial cells rests on it.
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Are epithelial cells single cells?
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No; they are a tissue - epithelium
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What do all glands consist of?
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Epithelial cells
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3 ways to organize epithelial tissue:
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1. Number of layers
2. Shape of cells 3. Cell membrane specializations |
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3 categories of ET based on number of layers:
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1. Simple
2. Stratified 3. Transitional |
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What is simple epithelium?
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One layer, every cell touches the basal lamina
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What is stratified?
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Epithelium that consists of more than one layer
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What is pseudostratified epithelium?
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Simple epithelium that looks like stratified
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What is transitional epithelium?
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Stratified epithelium that stretches when an organ is full, making it look like there are fewer cell layers than when relaxed.
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3 Classes of epithelial cells based on shape:
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-Squamous (flat)
-Cuboid (cube) -Columnar (rhomboid) |
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If epithelia tissue is stratified, which layer determines the cell shape type?
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Most superficial
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Which epithelial cell surface is free?
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Apical
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What are the 3 specializations along the lateral border of adjacent epithelial cells?
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1. Occluding junctions
2. Anchoring junctions (2 types) 3. Communicating junctions |
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What does the basal border of an epithelial cell interact with?
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The acellular basal lamina
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What are apical membrane specializations for?
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Interaction with environment
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3 Apical memb specializations:
what is the function of each? |
1. Cilia - for propulsion
2. Microvilli - for absorption 3. Glycocalyx - for protection and recognition |
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3 components of a cilia:
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-Basal body (centriole) consists of 9 microtubule triplets
-Shaft (axoneme) 9 + 2 doublets -Flagellum (is a type) |
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What is the shaft of microvilli made of?
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Actin microfilaments
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What is the base of a microvilli?
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Terminal web consisting of intermediate filaments and actin.
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2 places where cilia are commonly found:
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-Oviduct
-Respiratory tract |
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What is the ATPase motor on the Microtubules in a ciliary axoneme?
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Dynein
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What is the special cilia in sperm called?
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Flagellum
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Cilia are made of =
where Microvilli are made of = |
Cilia = microtubules
Microvilli = actin microfilaments |
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What are the names of the 4 lateral membrane specializations?
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1. Zonula occludens
2. Zonula adherens 3. Macula adherens 4. Gap junction |
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Which lateral specializations are included in the junctional complex?
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Zonula occludens/adherens and Macula adherens
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What is the other name for Zonula occludens?
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Tight junction
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Zonula means
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girdle
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What can pass through the zonula occludens?
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Only water and small solutes
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What are the tight junction proteins that regulate passage of solute molecules across the zonula occludens? (2)
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Occludins
Claudins |
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What makes up the submembrane plaque that tight junction proteins interact with?
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ZO proteins
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What zone is just beneath the zonula occludens?
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Zonula adherens
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What is the zonula adherens?
What does it look like? |
An anchoring junction
Completely encircles the cell |
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3 Components that make up the Zonula Adherens:
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1. Transmembrane linker protein
2. Subplasmalemmal plaque 3. Cytoskeletal filaments |
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What are the specific names of the 3 components of the Zonula Adherens anchoring junction?
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1. Cadheren
2. Plaque of a-actinin & vinculin 3. Actin microfilaments |
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What did the actin microfilaments used to be termed?
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Terminal web
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What is the MAcula ADherens?
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A desmosome
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What is the Macula Adherens made of? (3 components)
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1. Desmoglein (a cadherin)
2. Desmoplakin 3. Keratin intermediate filaments |
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How is the Macula adherens very different from the other 2 contributors to a junctional complex?
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It does not completely encircle the cell.
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4th type of lateral cell specialization not included in the junctional complex:
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Gap junctions - Connexons
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What are Gap junctions?
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Communicating junctions that provide electrical and metabolic communication between cells.
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What makes up Gap junctions?
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2 Connexons each composed of 6 Connexins.
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How do Gap junctions differ from other lateral specializations?
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There is no plaque or cytoskeletal protein associated with connexons.
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What 2 specializations occur in the basal membrane?
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1. Hemidesmosomes
2. Adhesion plaques |
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What is the function of basal specializations?
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Attachment to the basal lamina extracellular matrix - ANCHORING.
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What are hemidesmosomes?
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Half desmosomes
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How are hemidesmosomes different from normal desmosomes?
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Linker protein = INTEGRIN instead of desmoglein
Attach to Fibronectin in the extracellular matrix instead of an adjacent cell. |
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Major things to remember about cell-to-cell adhesion:
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-Ca dependent
-Cadherins mediate homotypic adhesion -Tissue-specific via Lectins |
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What would be heterotypic cell adhesion?
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Integrin binding to Fibronectin as in hemidesmosomes.
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What finetunes the actions of Cadherins?
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CAMs
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How often does skin turn over?
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Every 28 days
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How often do cells of the small intestine turn over?
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Every 5 days
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What is metaplasia?
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A change in epithelial cells to a biochemically different cell type.
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What is Carcinoma?
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Malignant tumor of epithelial cells
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What is an adenocarcinoma?
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A tumor of epithelial glandular cells
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How much cancer is due to epithelial cells?
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85%
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Tumors of epithelium express
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Keratin
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Tumors of glia express
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Glial fibrillary acidic protein
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Muscle tumors express
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desmin
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Connective tissue tumors express
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vimentin
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How are tumors diagnosed?
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By immunostaining for the IF protein in them.
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