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Basement of the epithelium
basal lamina
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Parenchyma
- -Epithelial portion of organs
- -Cells of an organ that provide function (i.e. hepatocyte)
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Stroma
- -Supporting connective tissue of organ
- -Connective tissue serves as support , structure, and protection of epithelial cells of the organ
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Name 5 functions of epithelium
- -Covering/lining surfaces (skin, mucus, GI tract, blood vessels)
- -Absorption (intestines)
- -Secretion (glands: salivary, intestinal)
- -Sensation (neuroepithelium: taste and smell)
- -Contractility (myoepithelium of sweat, salivary, lacrimal)
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4 Types of Epithelium
- -Shape
- -Specializations
- -Number of Layers
- -Function
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3 Types of Epithelial shapes
- -Squamous
- -Cuboidal
- -Columnar
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4 types of epithelial specialization
- -Cilia
- -Microvilli
- -Goblet cells
- -Keratinization
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4 Types of epithelial layering
- -Simple
- -Stratified
- -Pseudostratified
- -Transitional
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3 types of epithelial function
- -Covering epithelia
- -Glandular epithelia
- -Secretory cells
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All epithelial cells rest on an extracellular matrix called:
basal lamina
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4 functions of basal lamina
- -Supports the epithelial cells above
- -Acts as a diffusion barrier with pores that are semi-permeable
- -Controls cell organization and differentiation
- -Pathway for cell migration during development and healing
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5 Components of basal lamina
- -Type IV collagen
- -laminin
- -heparan sulfate
- -fibronectin
- -carbohydrates
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Example of simple squamos and function
- -lining of vessels; serous lining of cavities
- -Facilitates movement of viscera; Active transport of substances
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Example of simple cuboidal and function
- -Covering the ovaries or thyroid
- -Covering, secretion
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Exampe of simple columnar and function
- -Lining of intestine or gall bladder
- -Protection, lubrication, absorption, secretion
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Give example of Pseudostratified columnar and function
- -Lining of trachea, cronchi, nasal cavity, intestines
- -Protection, secretion, cilia-mediated transport, goblet cells, absorption
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Give example of Keratinized Stratified and function
- -Epidermis
- -Protection, prevents water loss
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Give example of Non-keratinized Stratified
- -Mouth, esophagus, vagina, anal canal
- -Protection, secretion, prevents water loss
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Give example of Stratified Cuboidal
- -Sweaet glands, ovarian follicles
- -Protection, secretion
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Give example of Stratified Transitional and function
- -Bladder, ureters
- -Protection, distensibility
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Give example of Stratified Columnar and functino
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How does simple squamous and cuboidal epithelium transport substances?
Active & passive
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Function of goblet cells and where they are found
- -Mucus secreting cells of epithelial tissues
- -Found primarily in the intestinal and respiratory tracts
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Give an example of Transitional Epithelium and where it is located
- -Lining the bladder and ureters
- -Protction and distensibility
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How do Facet cells function?
Change shape according to degree of bladder distention (cuboidal to squamos)
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Epithelial cells receive their blood from capillaries and nerve endings from plexuses in the unerlying:
lamina propria
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Definition of Communicating Junctions (Gap Junctions)
Control passage of chemical or electrical signals from cell to cell
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Function of Occluding Junctions (Tight Junctions)
- -Seals cells together in a sheet-like formation
- -Prevents movement of molecules between cells
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Function of Anchoring Junctions (Desmosomes/hemidesmosomes)
-Attach cells to other cells or to extracellular matrix
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Name the units that Gap Junctions contain and describe their characteristics
- -Connexon-Pair of 6 protein span lipid bilayer of adjacent cells
- -Each protein of connexon is called connexin
- -Permeability of gap is controlled by individual connexins
- -Cells are able to control permeability of these junctions
- -Serve as communicating junctions between adjacent cells
- -Gap junctions are important for coordinated, synchronized cell excitation (smooth/cardiac muscle contraction)
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Structure of Tight Junctions
- -Membranes of adjacent cells fuse, prevent material from moving between cells
- -Junction forms a "band" completely encircling adjacent cells
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Function of Tight Junctions
- -Prevent diffusion
- -Provides waterproofing
- -Prevent molecules from moving out of the gut lumen
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Structure of Desomosomes
- -Intracellular attachment protein that connects desmosome to intermediate filament in cytoplasm
- -Widely distrubed in animal cells
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Function of Desmosomes
- -Serve as anchoring junctions to bind cells together
- -Attachment sites for intermediate filaments of cytoplasm
- -Transmembrane linker protein (cadherin)
- -Hemidesomosomes bind cells to basal lamina
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