1. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Chapter 2 Tissues Silent Lecture This Lecture covers the following Topics: Defining Tissues 4 Tissues Types Classifications of each Tissue Type Characteristics of Each Type

2. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Tissues Cells work together in functionally related groups called tissues Tissue – a group of closely associated cells that perform related functions and are similar in structure

3. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Four Basic Tissue Types and Basic Functions Epithelial tissue – covering Connective tissue – support Muscle tissue – movement Nervous tissue – control

4. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Epithelial Tissue Covers a body surface or lines a body cavity Forms most glands Functions of epithelium Protection Absorption, secretion, and ion transport Filtration Forms slippery surfaces

5. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Special Characteristics of Epithelia Cellularity-composed almost entirely of cells, separated by minimal amount of extracellular material Specialized contacts – special cell junctions join adjacent epithelial cells Polarity – cells have an upper (apical) and lower (basal) surface

6. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Special Characteristics of Epithelia cont. Support by connective tissue – all sheets of epithelium are supported by a layer of connective tissue Avascular but innervated – epithelia does not contain blood vessels, but does contain nerve endings Regeneration – epithelia has a high regenerative capacity, meaning they can repair and replace cells at a high rate

7. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Special Characteristics of Epithelia Figure 4.1

8. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Classifications of Epithelia First name of tissue indicates number of cell layers Simple – one layer of cells Stratified – more than one layer of cells Last name of tissue describes shape of cells Squamous – cells wider than tall (plate-like) Cuboidal – cells are as wide as tall, like cubes Columnar – cells are taller than they are wide, like columns

9. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Classifications of Epithelia Figure 4.2

10. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Simple Squamous Epithelium Description – single layer of flat cells with disc- shaped nuclei Special types Endothelium (inner covering) – slick lining of hollow organs Mesothelium (middle covering) Lines peritoneal, pleural, and pericardial cavities Covers visceral organs of those cavities

11. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Simple Squamous Epithelium Function Passage of materials by passive diffusion and filtration Secretes lubricating substances in serosae Location Renal corpuscles Alveoli of lungs Lining of heart, blood and lymphatic vessels Lining of ventral body cavity (serosae)

12. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Simple Squamous Epithelium Figure 4.3a

13. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Simple Cuboidal Epithelium Description – single layer of cube-like cells with large, spherical central nuclei Function – secretion and absorption Location – kidney tubules, secretory portions of small glands, ovary surface

14. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Simple Cuboidal Epithelium Figure 4.3b

15. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Simple Columnar Epithelium Description – single layer of column-shaped (rectangular) cells with oval nuclei Some bear cilia at their apical surface May contain goblet cells Function Absorption; secretion of mucus, enzymes, and other substances Ciliated type propels mucus or reproductive cells by ciliary action

16. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Simple Columnar Epithelium Location Non-ciliated form Lines digestive tract, gallbladder, ducts of some glands Ciliated form Lines small bronchi, uterine tubes, and uterus

17. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Simple Columnar Epithelium Figure 4.3c

18. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Pseudostratified Columnar Epithelium Description All cells originate at basement membrane Only tall cells reach the apical surface May contain goblet cells and bear cilia Nuclei lie at varying heights within cells Gives false impression of stratification

19. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Pseudostratified Columnar Epithelium Function – secretion of mucus; propulsion of mucus by cilia Locations Non-ciliated type Ducts of male reproductive tubes Ducts of large glands Ciliated variety Lines trachea and most of upper respiratory tract

20. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Pseudostratified Ciliated Columnar Epithelium Figure 4.3d

21. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Stratified Epithelia Contain two or more layers of cells Regenerate from below Major role is protection Are named according to the shape of cells at apical layer

22. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Stratified Squamous Epithelium Description Many layers of cells – squamous in shape Deeper layers of cells appear cuboidal or columnar Thickest epithelial tissue – adapted for protection

23. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Stratified Squamous Epithelium Specific types Keratinized – contain the protective protein keratin Surface cells are dead and full of keratin Non-keratinized – forms moist lining of body openings

24. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Stratified Squamous Epithelium Function – Protects underlying tissues in areas subject to abrasion Location Keratinized – forms epidermis Non-keratinized – forms lining of esophagus, mouth, and vagina

25. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Stratified Squamous Epithelium Figure 4.3e

26. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Stratified Cuboidal Epithelium Description – generally two layers of cube-shaped cells Function – protection Location Forms largest ducts of sweat glands Forms ducts of mammary glands and salivary glands

27. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Stratified Cuboidal Epithelium Figure 4.3f

28. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Stratified Columnar Epithelium Description – several layers; basal cells usually cuboidal; superficial cells elongated Function – protection and secretion Location Rare tissue type Found in male urethra and large ducts of some glands

29. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Stratified Columnar Epithelium Figure 4.3g

30. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Transitional Epithelium Description Basal cells usually cuboidal or columnar Superficial cells dome-shaped or squamous Function – stretches and permits distension of urinary bladder Location Lines ureters, urinary bladder and part of urethra

31. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Transitional Epithelium Figure 4.3h

32. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Epithelial Surface Features Apical surface features Microvilli – finger-like extensions of plasma membrane Abundant in epithelia of small intestine and kidney Maximize surface area across which small molecules enter or leave Act as stiff knobs that resist abrasion

33. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Epithelial Surface Features Apical surface features Cilia – whip-like, highly motile extensions of apical surface membranes Contains a core of nine pairs of microtubules encircling one middle pair Axoneme – a set of microtubules Each pair of microtubules – arranged in a doublet Microtubules in cilia – arranged similarly to cytoplasmic organelles called centrioles Movement of cilia – in coordinated waves

34. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings A Cilium Figure 4.5a

35. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Lateral Surface Features – Cell Junctions Factors holding epithelial cells together Adhesion proteins link plasma membranes of adjacent cells Contours of adjacent cell membranes Special cell junctions

36. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Lateral Surface Features – Cell Junctions Desmosomes – two disc-like plaques connected across intercellular space Plaques of adjoining cells are joined by proteins called cadherins Proteins interdigitate into extracellular space Intermediate filaments insert into plaques from cytoplasmic side

37. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Desmosome Figure 4.7

38. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Lateral Surface Features – Cell Junctions Tight junctions (zona occludens) – close off intercellular space Found at apical region of most epithelial types Some proteins in plasma membrane of adjacent cells are fused Prevent molecules from passing between cells of epithelial tissue

39. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Tight Junction Figure 4.8

40. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Lateral Surface Features – Cell Junctions Gap junctions – passageway between two adjacent cells Let small molecules move directly between neighboring cells Cells are connected by hollow cylinders of protein

41. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Gap Junction Figure 4.9

42. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Exocrine Glands Ducts carry products of exocrine glands to epithelial surface Include the following diverse glands Mucus-secreting glands Sweat and oil glands Salivary glands Liver and pancreas

43. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Unicellular Exocrine Glands (The Goblet Cell) Goblet cells produce mucin Mucin + water  mucus Protects and lubricates many internal body surfaces Figure 4.10b

44. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Multicellular Exocrine Glands Have two basic parts Epithelium-walled duct Secretory unit

45. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Multicellular Exocrine Glands Classified by structure of duct Simple Compound Categorized by secretory unit Tubular Alveolar Tubuloalveolar

46. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Types of Multicellular Exocrine Glands Figure 4.11

47. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Exocrine Glands Ductless glands Secrete substances directly into bloodstream Produce molecules called hormones

48. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Connective Tissue Most diverse and abundant tissue Main classes Connective tissue proper Cartilage Bone tissue Blood Cells separated by large amount of extracellular matrix Common embryonic origin – mesenchyme

49. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Classes of Connective Tissue Figure 4.12

50. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Connective Tissue Proper Two main subclasses Loose connective tissue Dense connective tissue

51. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Areolar Connective Tissue – A Model Connective Tissue Areolar connective tissue Underlies epithelial tissue Surrounds small nerves and blood vessels Has structures and functions shared by other connective tissues Borders all other tissues in the body

52. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Major Functions of Connective Tissue Structures within areolar connective tissue Support and binding of other tissues Holding body fluids Defending body against infection Storing nutrients as fat

53. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Areolar Connective Tissue Fibers provide support Three types of protein fibers in extracellular matrix Collagen fibers Reticular fibers Elastic fibers Fibroblasts produce these fibers

54. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Areolar Connective Tissue Description Gel-like matrix with all three fiber types Cells – fibroblasts, macrophages, mast cells, white blood cells Function Wraps and cushions organs Holds and conveys tissue fluid Important role in inflammation

55. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Areolar Connective Tissue Location Widely distributed under epithelia Packages organs Surrounds capillaries

56. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Areolar Connective Tissue Figure 4.15b

57. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Areolar Connective Tissue Tissue fluid (interstitial fluid) Watery fluid occupying extracellular matrix Tissue fluid derives from blood Ground substance Viscous, spongy part of extracellular matrix Consists of sugar and protein molecules Made and secreted by fibroblasts

58. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Areolar Connective Tissue Main battlefield in fight against infection Defenders gather at infection sites Macrophages Plasma cells Mast cells Neutrophils, lymphocytes, and eosinophils

59. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Other Loose Connective Tissue Adipose connective tissue Reticular connective tissue