1. Tissues

2. Overview of Tissue Science Histology ◦The study of tissues Four Basic Tissue Types ◦Epithelial ◦Connective ◦Muscular ◦Neural Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

3. Overview of Tissue Science Tissues collections of cells and extracellular material perform a specific but limited range of functions the four tissue types, in varying combinations, form all of the structures of the human body Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

4. Overview An Orientation to the Tissues of the Body Figure 4-1

5. Epithelial Tissue Epithelium ◦An avascular layer of cells that forms a barrier that covers internal or external surfaces Glands ◦Secretory structures derived from epithelia Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

6. Epithelial Tissue Characteristics of Epithelia ◦Cells closely packed ◦Apical cells exposed to external or internal surface ◦Cells attached to basement membrane ◦Lack blood vessels ◦Cells continually replaced Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

7. Epithelial Tissue Functions of Epithelia ◦Physical protection ◦Permeability control ◦Sensation trigger ◦Specialized secretions Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

8. Epithelial Tissue Two Classes of Glandular Secretion ◦Exocrine secretion  Secretion onto a body surface ◦Endocrine secretion  Secretion (of hormones) into neighboring tissues and blood Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

9. Epithelial Tissue Intercellular Connections ◦Cell adhesion molecules ◦Cell junctions  Tight junctions  Gap junctions  Desmosomes Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

10. Epithelial Tissue Intercellular Connections Figure 4-2

11. Epithelial Tissue The Epithelial Surface ◦Microvilli  Abundant on transport cells  Dramatically increase surface area  Found in intestinal lining, kidney tubules ◦Cilia  Beat in coordinated fashion  Move fluid along surface  Found in airways, oviduct Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

12. Epithelial Tissue The Surfaces of Epithelial Cells Figure 4-3

13. Epithelial Tissue The Basement Membrane ◦Noncellular meshwork anchors basal cells ◦Underlies all epithelia ◦Hemidesmosomes attach basal cells ◦Resists passage of large molecules ◦Strengthens against distortion Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

14. Epithelial Tissue Epithelial Renewal and Repair ◦Exposure shortens cell life ◦Epithelium needs constant repair and replacement ◦Epithelial stem cells undergo mitosis ◦Epithelium grows up from base Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

15. Epithelial Tissue Classifying Epithelia ◦Number of layers  Simple (one cell thick)  Stratified (multiple cells thick) ◦Cell shape  Squamous (flat)  Cuboidal (cubic)  Columnar (tall columns) Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

16. Epithelial Tissue Table 4-1

17. Epithelial Tissue Simple Squamous Epithelium Figure 4-4(a)

18. Epithelial Tissue Simple Cuboidal Epithelium Figure 4-4(b)

19. Epithelial Tissue Simple Columnar Epithelium Figure 4-4(c)

20. Epithelial Tissue Pseudostratified Ciliated Columnar Figure 4-5(a)

21. Epithelial Tissue Transitional Epithelium Figure 4-5(b)

22. Epithelial Tissue Stratified Squamous Epithelium Figure 4-5(c)

23. Epithelial Tissue Glandular Epithelia ◦Three secretion mechanisms  Merocrine ◦ Exocytosis of vesicles  Apocrine ◦ Release of apical cytoplasm  Holocrine ◦ Burst of entire contents Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

24. Mechanisms of Glandular Secretion Figure 4-6

25. Glandular Epithelium Gland ◦Single cell or group of cells ◦Secrete substances into ducts, onto a surface, or into the blood

26. Glandular Epithelium Endocrine Glands ◦Secretions enter interstitial fluid and then diffuse directly into the bloodstream  Secretions = HORMONES ◦ Regulate metabolic and physiological activities to maintain homeostasis  Ex. Pituitary, thyroid, and adrenal glands

27. Glandular Epithelium Exocrine Glands ◦Secrete products into ducts that empty onto the surface of a covering and lining epithelium  Secretions include: ◦ Mucus ◦ Sweat ◦ Oil ◦ Earwax ◦ Saliva ◦ Digestive enzymes  Ex. Sudoriferous (sweat)glands ◦ Produce sweat to help lower body temperature  Ex. Salivary glands ◦ Secrete saliva  contains mucus and digestive enzymes

28. Glandular Epithelium Glands containing a combination of exocrine and endocrine tissue: ◦Pancreas ◦Ovaries ◦Testes

29. Classification of Exocrine Glands Unicellular glands ◦Single celled glands ◦Secrete mucus directly onto the surface of a lining epithelium Multicellular glands ◦Composed of many cells ◦Form distinctive microscopic structures or macroscopic organs  Ex: sudoriferous, sebaceous (oil), and salivary glands

30. Classification of Exocrine Glands Multicellular glands (continued) ◦Simple gland  Duct of the gland does not branch ◦Compound gland  Duct of the gland does branch ◦Tubular gland  Glands with tubular secretory parts ◦Acinar glands  Glands with rounded secretory portions ◦Tubuloacinar glands  Glands with both tubular and more rounded secretory portions

31. Classification of Exocrine Glands Simple Glands ◦Simple Tubular  Ex. Glands in the large intestine ◦Simple Branched Tubular  Ex. Gastric glands ◦Simple Coiled Tubular  Ex. Sweat glands

32. Classification of Exocrine Glands Simple Glands (continued) ◦Simple Acinar  Ex. Glands of the penile urethra ◦Simple Branched Acinar  Ex. Sebaceous glands

33. Classification of Exocrine Glands Compound Glands ◦Compound Tubular  Ex. Cowper’s glands ◦Compound Acinar  Ex. Mammary glands ◦Compound Tubuloacinar  Ex. Acinar glands of the pancreas

34. Intercellular Connections Cell Junctions ◦Contact points between plasma membranes of tissue cells ◦3 functions:  Forming seals between cells  Anchoring cells to one another or to extracellular material  Providing channels that allow ions and molecules to pass from cell to cell within a tissue

35. Intercellular Connections tight junctions ◦membranes of neighboring cells are pressed together, preventing leakage of extracellular fluid Desmosomes ◦anchoring junctions ◦fasten cells together into strong sheets Gap junctions ◦communicating junctions ◦provide cytoplasmic channels between adjacent cells

36. LE 6-31 Tight junctions prevent fluid from moving across a layer of cells Tight junction 0.5 µm 1 µm 0.1 µm Gap junction Extracellular matrix Space between cells Plasma membranes of adjacent cells Intermediate filaments Tight junction Desmosome Gap junctions

37. Gap Junctions

38. Tight Junctions

39. Desmosomes

40. Connective Tissues Connective Tissues Components ◦Specialized cells ◦Extracellular matrix  Space between cells  Protein fibers  Fluid phase (the ground substance) Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

41. Connective Tissues Functions ◦Structural framework ◦Fluid and solute transport ◦Physical protection ◦Tissue interconnection ◦Fat storage ◦Microorganism defense Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

42. Connective Tissues Classifying Connective Tissues ◦Connective tissue proper ◦Fluid connective tissues ◦Supporting connective tissues -blast = immature cells -cyte = mature cells Usually highly vascular ◦Except cartilage and tendons Have nerve supply ◦Except cartilage Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

43. Connective Tissues Major Types of Connective Tissue Figure 4-7

44. Collagen Fibers ◦Strong, resist pulling forces ◦Promote flexibility and toughness ◦25% of total protein in body Elastic Fibers ◦Smaller than collagen fibers ◦Form a network within a tissue ◦Promote resilience ◦Consist of elastin and fibrillin ◦Found in skin, blood vessel walls, and lung tissue Reticular Fibers ◦Consist of collagen in bundles coated with glycoprotein ◦Support walls of blood vessels ◦Supporting framework for soft organs (spleen, lymph nodes)

45. Connective Tissues Connective Tissue Proper ◦Three types  Loose connective tissue ◦ Example: beneath dermis of skin  Adipose tissue ◦ Example: “love handles”  Dense connective tissue ◦ Examples: dermis, tendons, ligaments Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

46. Connective Tissues Loose Connective Tissue Figure 4-9(a)

47. Connective Tissues Adipose Tissue Figure 4-9(b)

48. Connective Tissues Dense Connective Tissues Figure 4-9(c)

49. Connective Tissues Fluid Connective Tissues ◦Cells + a liquid ground substance  Blood ◦ RBCs, WBCs, platelets + plasma  Lymph ◦ Lymphocytes + lymph fluid Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

50. Connective Tissues Supporting Connective Tissue ◦Support the body  Bone (osseous tissue) ◦ Osteocytes + collagen + calcium salts  Cartilage ◦ Chondrocytes + firm gel Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

51. Connective Tissues Supporting Connective Tissue ◦Cartilage  Avascular  Covered by a fibrous perichondrium  Matrix primarily composed of collagen and proteoglycans  Cells called chondrocytes ◦ Found in lacunae (lacuna-singular) ◦ Maintain matrix  Three types of cartilage ◦ Hyaline cartilage ◦ Elastic cartilage ◦ Fibrocartilage Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

52. Connective Tissues Hyaline Cartilage Figure 4-10(a)

53. Connective Tissues Elastic Cartilage Figure 4-10(b)

54. Connective Tissues Fibrocartilage Figure 4-10(c)

55. Connective Tissues Bone (Osseous Tissue) ◦Matrix provides unique properties  Collagen fibers resist bending  Calcium salts resist compression ◦Diffusion through canaliculi nourishes osteocytes ◦Covered by periosteum Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

56. Connective Tissues Bone Figure 4-11

57. Membranes Types of Membranes ◦Mucous  Lines cavities that connect to exterior  Mucous moistens surface ◦ Examples: oral cavity, airways ◦Serous  Line internal cavities  Watery fluid moistens surface ◦ Example: peritoneal membrane Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

58. Membranes Types of Membranes (continued) ◦Cutaneous  Covers body surface  Dry surface waterproofs the body ◦ Example: the skin ◦Synovial  Lines joints  Secretes slippery synovial fluid  Lubricates joints ◦ Examples: knee, elbow Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

59. Membranes Membranes Figure 4-12

60. Muscle Tissue Properties of Muscle Tissue ◦Capable of contraction  Actin filaments  Myosin filaments ◦Three types of muscle tissue  Skeletal muscle  Cardiac muscle  Smooth muscle Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

61. Muscle Tissue Skeletal Muscle Tissue Figure 4-13(a)

62. Muscle Tissue Cardiac Muscle Tissue Figure 4-13(b)

63. Muscle Tissue Smooth Muscle Tissue Figure 4-13(c)

64. Neural Tissue Figure 4-14

65. Tissue Injuries and Repair An injury harms multiple tissues simultaneously Tissues make coordinated response Responses restore homeostasis Two response types ◦Inflammation ◦Restoration Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

66. Tissue Injuries and Repair Inflammation ◦Isolation of injured area ◦Cleanup of damaged tissue ◦Four signs of inflammation  Warmth  Redness  Swelling  Pain Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

67. Tissue Injuries and Repair Regeneration ◦Repair/replacement of damaged tissue ◦Restoration of tissue function ◦Scar tissue from fibroblast activity ◦Complete, partial, or no regeneration ◦Tissue fibrosis common outcome  Formation of excess fibrous connective tissue Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

68. Tissues and Aging Tissues Change with Age ◦Healing slows ◦Epithelia become thinner ◦Connective tissues become more fragile ◦Bones weaken, become brittle ◦Neuron and muscle fiber losses accumulate ◦Lifestyle interventions slow decline Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

69. Tissues and Aging Aging and Cancer Incidence ◦25% develop cancer ◦Cancer risk rises with age ◦After heart disease, cancer second leading cause of death ◦Smoking linked to 40% of cancers ◦75% caused by environment Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings