mbbs ims msu

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Epithelial

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mbbs ims msu

  1. 1. TISSUES Assoc. Prof. Dr. Karim Al-Jashamy MSU/ IMS 2009
  2. 2. Tissue • Groups of cells that share a common structure and function. • In adult organisms, there are four tissue types: • Epithelium tissue • Connective tissue • Muscle tissue • Nervous tissue
  3. 3. Epithelium • Epithelial tissues are thin sheets. • Cover body surfaces and organs. • Line body cavities. •Occur at boundaries between two environments.
  4. 4. Epithelium • Functions include: • protection • sensory reception • secretion • absorption • ion transport • filtration • formation of slippery surfaces for substance movement.
  5. 5. Epithelium Special characteristics of epithelium separate it from the other basic tissue types: • Specialized contacts • Polarity • Support by connective tissue • Avascular but innervated • Regeneration • Cellularity
  6. 6. • Classification of Epithelia • • Epithelium is given two names. • • The first name indicates the number of cell layers. • • The second name identifies cell shape. • • Simple epithelium is a single layer of cells. • • Stratified epithelium • has more than one layer.
  7. 7. Simple Squamous Epithelium • • Single layer of flat cells. • • Found wherever diffusion or filtration are important. – Capillary linings, alveoli of lungs. • • Endothelium: –Special lining tissue (slippery). –Blood vessels, heart, lymphatic vessels. • • Mesothelium: peritoneal lining tissue – (serosa).
  8. 8. Epithelial Tissues • General Features Cellular Layer + Basement Membrane
  9. 9. Epithelial Tissues • General Features Cellular Layer + Basement Membrane No Direct Circulation/Blood Supply Touch Each Other Rapid Rate of Cell Reproduction
  10. 10. Epithelial Tissues • Structural Classification Cell Shapes
  11. 11. Squamous Cuboidal Columnar
  12. 12. Epithelial Tissues • Structural Classification Cell Shapes Cell Layers
  13. 13. Simple
  14. 14. Stratified
  15. 15. Epithelial Tissues • Major Types
  16. 16. Simple Squamous Epithelium
  17. 17. Simple Squamous Epithelium Function: Exchange Sample Locations: Alveoli, capillaries
  18. 18. Stratified Squamous Epithelium
  19. 19. Stratified Squamous Epithelium Function: Protection Sample Locations: Skin, Mouth, Repro tracts
  20. 20. Stratified squamous epithelium (non-keratinized)
  21. 21. Simple Cuboidal Epithelium Function: Absorption or Secretion Sample Locations: Kidney, Hormone Glands
  22. 22. Simple cuboid epithelium
  23. 23. Simple Columnar Epithelium Function: Absorption (or Secretion) Sample Location: Digestive Tract Microvilli
  24. 24. Simple columnar epithelium
  25. 25. Simple Columnar Note goblet cells
  26. 26. Pseudostratified Columnar Epithelium Note cilia
  27. 27. Pseudostratified Columnar Epithelium
  28. 28. Pseudostratified Columnar Epithelium Function: Absorption, Secretion, Movement Sample Locations: Respiratory & Repro Ducts
  29. 29. Pseudostratified epithelium
  30. 30. Transitional Epithelium Function: Stretchability Sample Location: Urinary Bladder
  31. 31. Transitional epithelium
  32. 32. Epithelium cont. • Epithelium that lines cavities sits on lamina propria. – Supports epithelium – Binds epithelium to other tissue – Provides nutrition • Sides of cells are named – Basal – Apical (free) – Lateral
  33. 33. Special Features of Epithelial Cells • – Cell junctions are lateral surfaces features that primarily bind adjacent cells to each other. • – Main types: • – tight junction (zonula • occludens) • – adherens junction • (zonula adherens) • – desmosome • – gap junctions
  34. 34. Avascular • • Epithelium lacks blood vessels (avascular). • • Epithelium does have some nerve endings that go between cells (innervated).
  35. 35. Gap Junction
  36. 36. Intercellular Junctions Belts that circle cell. ZO (tight junction) acts as barrier. ZA provides for adhesion of one cell to another Spots Des is like a spot welding. Gap allows passage of chemical for communication.
  37. 37. Specializations of Cell Surface • Microvilli – Found mainly on absorptive cells – Brush border, 1m high • Cilia / flagella – Cylindrical, motile structures, 5-10m high – Contain microtubules – Basal bodies
  38. 38. Microvilli Apical region of an intestinal epithelial cell seen with TEM. Filaments that constitute the core of the microvilli are clearly seen. An extracellular cell coat (glycocalyx) is bound to the plasmalemma of the microvilli. x45,000.
  39. 39. Cilia
  40. 40. Regeneration • • Epithelium can regenerate.
  41. 41. Glands • • Many epithelial cells make and secrete a product. • • Glands are classed as exocrine (with ducts), or • endocrine (without ducts), as well as – • unicellular – or multicellular. • • One-celled exocrine gland is the goblet cell; its product is mucin • • Endocrine glands secrete hormones.
  42. 42. Multicellular Exocrine Glands • • Glands have two parts: – –Secretory portion – –Duct • –Both surrounded by fibrous capsule.
  43. 43. Multicellular Exocrine Glands • Simple glands – Unbranched duct • Compound glands – Branched duct – Tubular – Alveolar – Tubuloalveolar
  44. 44. Special Features of Epithelial Cells • The basal lamina separates the epithelium and underlying connective tissues. • Apical surface features are microvilli and cilia.
  45. 45. Connective Tissue Connective tissue is the most diverse and abundant type of tissue. Cells are separated by extracellular matrix. Four main classes and many subclasses • Connective tissue proper (loose and dense) • Cartilage • Bone tissue • Blood
  46. 46. General Features of CT – General structural features: – fibroblast – fibers (collagen, reticular, and elastic) – ground substance – General functional features: – support and binding – holding tissue fluid – fighting infection – storing fat
  47. 47. Connective Tissue • Loose areolar connective tissue represents general structural and functional elements of connective tissue. • This CT underlies epithelia and surrounds nerves and vessels. • 3 types of extracellular matrix fibers made by fibroblasts: – Collagen – Reticular – Elastic
  48. 48. Connective Tissue • Ground substance: jellylike materials that hold interstitial fluid. – Glysoaminoglycans – Proteoglycans
  49. 49. Defense Cells • Areolar CT contains many defense cells. –Macrophages –Plasma cells –Mast cells –Neutrophils, lymphocytes, eosinophils
  50. 50. Connective Tissue Classification Connective tissue proper has two subdivisions: Loose connective tissue • Loose connective tissues : • adipose (fat) • reticular (bone marrow)
  51. 51. Connective Tissue Classification Dense connective tissue (fibrous connective tissue) Contains more collagen than areolar tissue. • Dense connective tissue: • Regular • Irregular
  52. 52. • Connective Tissue Classification • • Other connective tissues: • • Cartilage (supporting rings of trachea) • • Bone (skeleton) • • Blood
  53. 53. Covering and Lining Membranes – Covering and lining membranes combine connective and epithelial tissues. – There are three types of covering and lining membranes: • Cutaneous (skin) • Serous (line body cavities) • Mucous (line hollow organs) – Underlying CT is lamina propria
  54. 54. Simple Squamous (endothelium)
  55. 55. Simple squamous (mesothelium) Lines a body cavity Such as abdominal cavity.
  56. 56. References • • Martini. 2002. Fundamental of Anatomy and Physiology. 5th edition. • Prentice Hall International, Inc. • • Norman, F., Gant, F. & Cunningham, G. (1993). Basic Gynecology • and obstetrics. A Lange medical book. Appleton & Lange • • Ganong, W.F. 2005. Review of Medical Physiology, 20th Ed, • Appleton & Lange • • Sherwood, L. 2001. Human Physiology – From Cells to Systems. • 6th edition. McGraw Hill. • • Marieb, E.N. 1998. Human Anatomy and Physiology, 4th Ed, • Addison Wessley Longman Inc, New York. • • Tortora, G.J. dan Grabowski, S.R. 2000. Principles of Anatomy and • Physiology, 9th Ed., John Wiley & Sons, New York

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