Anatomy Ch 4

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Anatomy Ch 4
2010-09-12 08:45:20
Anatomy epithelial tissue

Notes and text from Ch 4 - Tissue
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  1. Four types of body tissue
    • Epithelial
    • Connective
    • Muscular
    • Nervous
  2. Epithelial Tissue
    • avascular - lacks own blood supply - nutrients and waste move via adjacent connective tissue
    • epithelium - consists of cells arranged in continuous sheets (in single or multiple layers) - closely packed - little intercellular space
    • covers body surfaces and lines hollow organs, body cavities, and ducts
    • also forms glands
  3. connective tissue
    • bones and blood
    • protects and supports body and organs
    • binds organs together, stores energy reserves as fat, help provide immunity to disease-causing organisms
  4. Nervous tissue
    detects changes in a variety of conditions (inside and outside the body) - responds by generating action potential (nerve impulses) the help homeostasis
  5. primary germ layers
    • first tissues formed in human embryo
    • ectoderm - form epithelial and nervous tissue
    • endoderm - form epithelial tissue
    • mesoderm - form epithelial and connective tissue
  6. phagocytes
    move freely through body looking for invaders to destroy
  7. Tissue
    group of similar cells that have a common embryonic origin and function together for a specific function
  8. Histology
    science that studies tissue
  9. pathologist
    physician who specializes in lab studies of cells and tissue to help other physicians make accurate diagnoses
  10. lumen
    hollow area that is filled with something
  11. muscular tissue
    generates the physical force needed to make body structures move
  12. Cell Junctions
    contact points between the plasma membranes of tissue cells
  13. Types of Cell Junctions
    • 1. Tight Junction
    • 2. adherens junction
    • 3. desmosomes
    • 4. hemidesmosomes
    • 5. gap junctions
  14. Tight Junction
    • weblike strands of transmembrane proteins - linkers
    • fuse the outer surfaces of adjacent plasma membranes together
    • close together - stuff not able to pass between cells
  15. Adherens junction
    adhesion belts
    • contains plaque - intracellular (space between cells) space exists - stuff can move between cells
    • plaque - inside plasma membrane that attaches to membrane proteins & microfilaments
    • cadherins - transmembrane glycoproteins that attach to plaque in adjacent cells and binds them
    • adhesion belts - epithelial cells - extensive zones of adherens junctions
  16. Desmosomes
    • similar to adherens - involves plaque and cadherens - but does not attached to microfilaments
    • Connects to intermediate filaments
    • filaments extend across cell from desmosome to desmosome (spot-weld jucntions)
    • very strong - give strength to cell and junctions - prevent cardiac muscle cells from pulling apart diring contraction
  17. hemidesmosomes
    • hemi = half
    • resemble half a desmosome
    • integrins - transmembrane glycoprotein used (not catherins as in desmosomes)
    • attaches the cell to the basement membrane with laminin
    • laminin - protein in the basement membrane that hemidesmosome is attached to
  18. Gap junctions
    • connexins - membrane protein that form tiny fluid-filled tunnels (connexons) that connect neighboring cells
    • cells not fused - separated by intracellular space
    • connects cytosol of neighboring cells - allow communication & transfer of nutrients and waste
  19. Parts of Epithelial tissue
    • 1. apical surface - free surface - faces the body surface, a body cavity, the lumen of an internal organ, or tubular duct (may contain cilia or microvilli)
    • 2. lateral surfaces - face adjacent cells on either side
    • 3. basil surface - opposite surface of deepest layer adhere to basement membrane
    • 4. basement membrane - supports epithelial and attaches to connective tissue
    • a. basal lamina - closer to epithelial cells
    • b. reticular lamina - closer to connective tissue - attached to connective tissue with fibroblasts
  20. Functions of epithelial tissue
    • protection
    • absorption
    • secretion
    • excretion
  21. Two types of epithelial tissue
    • 1. covering and lining epithelium
    • 2. glandular epithelium
  22. Covering and lining epithelium
    classification system
    • classified by arrangement of cells into layers and shape of cells
    • Cell Layers-
    • 1. simple epithelium - singe layer of cells
    • 2. pseudostratified epithelium - (false) appear to have multiple layers because nuclei lie at different levels
    • 3. Stratified epithelium - two or more layers
    • Cell Shapes
    • 1. squamous cells - flat - allow for rapid passage of substances
    • 2. cuboidal cells - relatively cube shape - function for secretion or absorption
    • 3. columnar cells - taller than wide
    • 4. transitional cells - change shape - bladder - expand to larger size and collapse to smaller size
  23. simple squamous epitherium
    • single layer of flat cells - nucleus is a flattened oval or sphere and it centrally located
    • allows passage - sites where filtration (blood through kidneys) or diffusion (blood into oxygen)
    • endothelium - simple squamous epithelial cells that line the heart, blood vessels, lymphatic vessels
    • mesothelium - the epithelial layer or serous membranes (peritoneum)
  24. Simple cuboidal epithelium
    • secretions & absorption, ducts (tubules) lumen in the middle (unfilled area)
    • relatively cube shape with round nucleus in the middle
  25. Simple columnar epithelium
    nonciliated simple columnar
    ciliated simple columnar epithelial
    • secretion & absorption, ducts (tubules) - lumen in the middle (unfilled area)
    • shaped like a column with a oval nucleus near the base
    • nonciliated simple columnar - contains two type of cells - columnar epithelial cells with microvilli at their apical surface & goblet cells
    • microvilli - fingerlike cytoplasmic projections - increase surface area
    • goblet cells - modified columnar epithelial cells that secrete mucus
    • ciliated simple columnar epithelial - contains columnar epithelial cells with cilia at the apical surface
  26. pseudostratified columnar epithelium
    • pseudo = false...looks like more than one layer but all cells are attached to basement membrane
  27. stratified squamous epithelium
    • two or more layers of cells - more durable, can protect underlying tissue - some produce secreations
    • cells in apical layer are flat - basal cells continually undergo cell division - as new cells grow the basal layer is pushed upward toward the apical layer. Cells at apical layer farther from blood supply - die and loose cell junctions - slought off
  28. keratin
    keratinized stratified squamous epithelium
    nonkeratinized stratified squamous epithelium
    • tough, fibrous protein - protects skin and underlying tissue
    • keratinized stratified squamous epithelium - apical layer and several layers deep are paritally dehydrated and contain a layer of keratin - form superficial layer of skin
    • nonkeratinized stratified squamous epithelium - lines mouth & espphagus - does not contain keratin and is moist
  29. Transitional Epithelium
    only present in urinary syste m - cells in apical layer look "puffy" (large and rounded) - able to stretched and return to original shape