1. Tissues: The living fabric Ch 4 a Epithelial Tissue

3. Tissues Histology = Study of tissues Tissue = Groups of cells similar in structure and function The four types of tissues –Epithelial - covering –Connective - support –Muscle - movement –Nerve - control

4. Epithelial Tissue 2 types –Covering and lining epithelium –Glandular epithelium

5. Epithelial Tissue Epithelial Tissue Covering and lining epithelium

6. Epithelial Tissue A sheet of cells that covers a body surface or lines a body cavity Forms boundaries between different environments

7. Epithelial Tissue Functions Protection Absorption Filtration Excretion Secretion (from glands) Sensory reception

8. Characteristics of Epithelial Tissue Cellularity – composed almost entirely of cells –Very little extracellular material Special contacts – form continuous sheets held together by tight junctions and desmosomes

9. Characteristics of Epithelial Tissue Polarity – apical and basal surfaces –Apical = free upper surface exposed to exterior of body or cavity (some are slick, some have cilia, most have microvilli) –Basal = lower surface attached

10. Characteristics of Epithelial Tissue Basal surface attached to basement membrane

11. Characteristics of Epithelial Tissue Basal surface attached to basement membrane –basal laminae – thin, adhesive, non-cellular –reticular laminae – fine network of collagen fibers belonging to the connective tissue underneath, non-cellular

12. Characteristics of Epithelial Tissue All epithelial tissue are supported by and rest upon connective tissue

13. Characteristics of Epithelial Tissue Avascular but innervated – contains no blood vessels but supplied by nerve fibers – nourished by diffusion Regenerative – rapidly replaces lost cells by cell division

14. Classification of Epithelia Simple stratified Figure 4.1a

15. Classification of Epithelia Squamous Cuboidal Columnar Figure 4.1b

16. Epithelia: Simple Squamous Single layer of flattened cells with disc-shaped nuclei and sparse cytoplasm

17. Epithelia: Simple Squamous Functions –Diffusion and filtration –Provide a slick, friction-reducing lining in lymphatic and cardiovascular systems Present in the kidneys, lungs, lining of heart, blood vessels, lymphatic vessels

18. Epithelia: Simple Squamous Figure 4.2a

19. Epithelia: Simple Cuboidal Single layer of cubelike cells with large, spherical central nuclei Function in secretion and absorption Present in kidney tubules, ducts and secretory portions of small glands, and ovary surface

20. Epithelia: Simple Cuboidal Figure 4.2b Single layer of cubelike cells with large, spherical central nuclei Function in secretion and absorption Present in kidney tubules, ducts and secretory portions of small glands, and ovary surface

21. Epithelia: Simple Columnar Single layer of tall cells with oval nuclei; many contain cilia Goblet cells are often found in this layer –Cells that secrete a protective lubricating mucus Function in absorption and secretion

22. Epithelia: Simple Columnar Nonciliated type line digestive tract and gallbladder Ciliated type line small bronchi, uterine tubes, and some regions of the uterus Cilia help move substances through internal passageways

23. Epithelia: Simple Columnar Figure 4.2c

24. Epithelia: Pseudostratified Columnar Single layer of cells with different heights; some do not reach the free surface Nuclei are seen at different layers

25. Epithelia: Pseudostratified Columnar Function in secretion and propulsion of mucus Present in the male sperm- carrying ducts (nonciliated) and trachea (ciliated)

26. Epithelia: Pseudostratified Columnar Figure 4.2d Single layer of cells with different heights; some do not reach the free surface Nuclei are seen at different layers Function in secretion and propulsion of mucus Present in the male sperm-carrying ducts (nonciliated) and trachea (ciliated)

27. Epithelia: Stratified Squamous Thick membrane composed of several layers of cells Function in protection of underlying areas subjected to abrasion

28. Epithelia: Stratified Squamous Forms the external part of the skin’s epidermis (keratinized cells), and linings of the esophagus, mouth, and vagina (nonkeratinized cells)

29. Epithelia: Stratified Squamous Figure 4.2e Thick membrane composed of several layers of cells Function in protection of underlying areas subjected to abrasion Forms the external part of the skin’s epidermis (keratinized cells), and linings of the esophagus, mouth, and vagina (nonkeratinized cells)

30. Epithelia: Stratified Cuboidal Stratified cuboidal –Quite rare in the body –Found in some sweat and mammary glands –Typically two cell layers thick

31. Epithelia: Stratified Columnar Stratified columnar –Limited distribution in the body –Found in the pharynx, male urethra, and lining some glandular ducts –Also occurs at transition areas between two other types of epithelia

32. Epithelia: Transitional Several cell layers, basal cells are cuboidal, surface cells are dome shaped Stretches to permit the distension of the urinary bladder Lines the urinary bladder, ureters, and part of the urethra

33. Epithelia: Transitional Figure 4.2f Several cell layers, basal cells are cuboidal, surface cells are dome shaped Stretches to permit the distension of the urinary bladder Lines the urinary bladder, ureters, and part of the urethra

34. Epithelial Tissue Epithelial Tissue Glandular Epithelia

35. Epithelia: Glandular A gland is one or more cells that makes and secretes an aqueous fluid

36. Epithelia: Glandular Glands Classified by: –Site of product release – Endocrine (internally secreting) or Exocrine (externally secreting) –Relative number of cells forming the gland – Unicellular (one cell) & Multicellular (many cells)

37. Endocrine Glands Ductless glands that produce hormones Secretions include amino acids, proteins, glycoproteins, and steroids

38. Exocrine Glands More numerous than endocrine glands Secrete their products onto body surfaces (skin) or into body cavities

39. Exocrine Glands Examples include mucous, sweat, oil, and salivary glands, the liver (which secrets bile), the pancreas (which secrets enzymes) and others

40. Unicellular Exocrine Glands The only important unicellular exocrine gland is the goblet cell –Found in linings of intestinal and respiratory tracts –Secrets mucus

41. Multicellular Exocrine Glands Multicellular exocrine glands are composed of a duct and secretory unit Classified according to: –Simple or compound duct type –Structure of their secretory units

42. Figure 4.3a-d Structural Classification of Multicellular Exocrine Glands

43. Figure 4.3e-g

44. Modes of Secretion Merocrine – products are secreted by exocytosis (e.g., pancreas, sweat, and salivary glands) Holocrine – products are secreted by the rupture of gland cells (e.g., sebaceous glands)

45. Modes of Secretion Figure 4.4 MerocrineHolocrine

46. http://www.youtube.com/watch?v=7z2v Yr5YjD8http://www.youtube.com/watch?v=7z2v Yr5YjD8

48. Simple cuboidal epithelium

52. Transitional epithelium

56. Pseudostratified epithelium

58. Stratified squamous epithelium

59. What tissue is this?

62. Simple columnar epithelial tissue

63. Quiz – Next time! I will be checking study guides up to 1-8

64. Ap = tip Areola = space Basal = foundation Blast = forming Chyme = juice Crine = separate Endo = within Epi = upon, over Glia = glue Holo = whole Hormon = excite Hyal = glass Lamina = thin plate Mero = part Meso = middle Retic = network Sero = watery fluid Squam = a scale Strat = layer