Chapter4 tissuesmariebpart1


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Chapter4 tissuesmariebpart1

  1. 1. Chapter 4: Tissues, Part 1Tissue = A collection of cells that perform related functions,and are similar in structure, or a mass of like cellsHistology = The study of tissuesThe Four Primary Tissue Types Epithelial Connective Muscular Nervous Developed by John Gallagher, MS, DVM
  2. 2. Epithelial Tissue 1. Epithelium / -a = cell layer (barrier)  Epi = on or upon  Protection: covering or lining—inside and out  Permeability control: selective secretion and absorption  Sensation: touch receptors etc. and neuroepithelium of special senses 2. Glands = secretory structure  Specialized secretions  Saliva, hormones, many others •The Four Primary Tissue Types Epithelial Connective Muscular Nervous
  3. 3. A Concept Map Epithelial tissues Squamous Columnar CuboidalSimple Stratified Simple Simple Keratinized Pseudostratified Stratified Nonkeratinized Transitional
  4. 4. Structural Characteristics ofEpithelia p 69apical Cellularity (little to no IC Space) Cell to cell contacts Polarity (sometimes)basal Basement Membrane Support by connective tissue BM Avascular (esp. epidermis) Regeneration/repair
  5. 5. Polarity of (some) Epithelial Cells
  6. 6. Classification of EpitheliaThe function of the epithelium determines which type.Typically classified according to 1. Number of cell layers Simple vs. Stratified 2. Shape of cell Squamous, cuboidal, columnar
  7. 7. Simple Squamous EpitheliumLocation: Lining of ventral body cavities, e.g. peritoneum Lining of blood vessels (endothelium) Alveoli of lung Bowman’s Capsule
  8. 8. Function of Simple Squamous E. Friction reduction (cavity lining) Blood vessel permeability control (capillaries and Bowman’s capsule) Gas absorption and secretion (lung) Not protective—only one cell thick
  9. 9. Lung
  10. 10. Simple Cuboidal Epithelium Function:  Secretion  Absorption Location: Lining of ducts  e.g., kidney tubules  Glands (salivary, pancreas, thyroid)
  11. 11. Kidney tubuleThyroid Follicle
  12. 12. Simple Columnar Epithelium The “classic” epithelium Function:  Secretion  Absorption Location:  GI tract  Many excretory ducts Cilia (uterine tube) Microvilli (small intestine)
  13. 13. Pseudostratified Ciliated Columnar Epithelium Function: Mucociliary Blanket Mixture of cell types  nuclei located at various distances from surface. Yet: all cells contact BM Location: Ducts of Respiratory tract  i.e., trachea and bronchi
  14. 14. Stratified Squamous Epithelium  Function Protection against abrasion, pathogens, chemicals, heat/cold…  Keratinized vs. non-keratinized  Location ? Where we need protection! Skin surface Entrances/exits of body, e.g. mouth, vagina
  15. 15. Nonkeratinized (noncornified)stratified squamous epithelium
  16. 16. Keratinized (cornified) stratifiedsquamous epithelium Thick skin
  17. 17. Stratified cuboidal and stratified columnar:quite rare, found in glands and ducts Sweat gland
  18. 18. Transitional Epithelium  Function ? Extreme expansion & recoil  Layered appearance due to overcrowding. All cells contact BM.  Location ?  Bladder, ureters, renal pelvis
  19. 19. stretched
  20. 20. Bladder
  21. 21. Glandular Epithelia Types of Glandular Secretions:  Exocrine  Endocrine  Glands have ducts  Glands have no  Secretion to the ducts “outside” of the body  Hormones (into  Simple or compound the bloodstream)