Ch. 4: Tissue: The Living Fabric Microscopy Epithelial Tissue Connective Tissue Nervous Tissue Muscle Tissue Covering an

1. Ch. 4: Tissue: The Living Fabric Microscopy Epithelial Tissue Connective Tissue Nervous Tissue Muscle Tissue Covering and Lining Membranes Wound repair; development

2. Microscopy • Microscopic Anatomy • Fix (Preserve) • Section (Slice) • Stain (Add Contrast) • Light Microscopy • Add color • Different stains for different tissues • H&E the default • Different aspects of different tissues • Electron Microscopy • Add heavy metal to deflect electron beam • Artifacts of fixation, sectioning, staining

3. Skeletal muscle, H&E stain www.anatomy.uiowa.edu/genhisto/GHWIN/unit1/image/i-08.jpg

4. Light microscopy: organ of Corti, ear Keele University, UK, www.keele.ac.uk/depts/bi/emunit/galleries/gallery1/index.htm

5. Scanning electron microscopy: organ of Corti, ear Keele University, UK, www.keele.ac.uk/depts/co/em96/em96.htm

6. Outer hair cells, ear Scanning and transmission electron micrographs Keele University, UK, www.keele.ac.uk/depts/co/em96/em96.htm

7. Epithelial Tissue • Special Characteristics • Polarity, sidedness: apical (microvilli), basal • Specialized contacts on the sides: tight junctions, desmosomes • Supported by connective tissue: basal lamina (noncellular) and reticular connective tissue below • Avascular, innervated • High regeneration rate • Classification • Glandular

8. Epithelial Tissue • Special Characteristics • Classification • Two-part names • Part 1: cell layers • Simple (1), stratified (>1) • Part 2: shape (of apical layer in stratified) • Squamous, cuboidal, columnar • Glandular

9. Figure 4.1

10. Figure 4.2a

11. Figure 4.2b

12. Figure 4.2c

13. Figure 4.2d

14. Figure 4.2e

15. Figure 4.2f

16. Epithelial Tissue • Special Characteristics • Classification • Glandular • Endocrine glands • Make & release hormones into blood; ductless; most are small organs; ch. 16 • Exocrine glands • Make & secrete product to “outside” • Unicellualr: goblet cell make mucin, forms mucus; resp & GI tracts • Multicellular: duct & secretory unit (acinus); sweat, various in GI tract, mammary, salivary

17. Goblet cell Unicellular exocrine gland Figure 4.3

18. Types of multicellular exocrine glands Classified by structure Figure 4.4

19. Connective Tissue • Common Characteristics • Origin: embryonic mesenchyme • Large amount of extracellular matrix • Structural Elements • Ground substance – between the cells • Fibers • Collagen • Elastic • Reticular • Cells • See Fig 4.6. • -blasts vs. -cytes • Types

20. Figure 4.6

21. Connective Tissue • Types • Connective Tissue Proper • Loose • Areolar: support, hold fluid, defense v. infection • Adipose: cushion, store energy, insulate; often subQ • Reticular: like areolar but only retic fibers; many lymphocytes; lymph nodes, spleen, bone marrow • Dense (Fibrous: fibers are main component) • Regular: unidirectional collagen fibers; ligaments, tendons • Irregular: multidirectional collagen fibers; makes sheets; dermis, joint capsules, etc. • Elastic: elastic (large) arteries • Cartilage • Bone • Blood

22. Areolar connective tissue as general connective tissue example Extracellular matrix Cell types Ground substance Macrophage • Collagen fiber • Elastic fiber • Reticular fiber Fibroblast Lymphocyte Fat cell Capillary Mast cell Neutrophil Figure 4.7

23. Figure 4.8a

24. Figure 4.8b

25. Figure 4.8c

26. Figure 4.8d

27. Figure 4.8e

28. (f) Connective tissue proper: dense connective tissue, elastic Description: Dense regular connective tissue containing a high proportion of elastic fibers. Function: Allows recoil of tissue following stretching; maintains pulsatile flow of blood through arteries; aids passive recoil of lungs following inspiration. Location: Walls of large arteries; within certain ligaments associated with the vertebral column; within the walls of the bronchial tubes. Elastic fibers Aorta Elastic connective tissue in the wall of the aorta (250x) Heart Figure 4.8f

29. Connective Tissue • Common Characteristics • Structural Elements • Types • Connective Tissue Proper • Cartilage • Hyaline c. • Elastic c. • Fibrocartilage • Bone • Blood

30. Collagen • Most abundant protein in the body • Type I (most common): In bone, scar tissue, tendons, ligaments. • Type II: Hyaline cartilage. • Type III: Found in extracellular matrix of early granulation (wound healing) tissue; replaced by type I collagen in mature scar tissue. • Type IV: Lens of eye; basal lamina beneath epithelium (esp. in skin, beneath epidermis); capillaries, including glomeruli. • Type V: Interstitial tissue (loose connective tissue); placenta. • List goes up to XXVIII=28…

31. Collagen Structure Has 3 subunits (strands) which wrap around each other with a right-handed (RH) twist – i.e. a triple helix. Each subunit (strand) is a LH helix (not an a-helix which is RH). Combination of RH and LH helices makes collagen hard to stretch. How to tell the handedness of a helix: fingers show sense of rotation when travelling in direction that thumb points. Julian Voss-Andreae "Unraveling Collagen: a metaphor for aging and growth” http://en.wikipedia.org/wiki/Image:Collagentriplehelix.png

32. Figure 4.8g

33. Figure 4.8h

34. Figure 4.8i

35. Connective Tissue • Common Characteristics • Structural Elements • Types • Connective Tissue Proper • Cartilage • Bone • Blood

36. Figure 4.8j

37. Connective Tissue • Common Characteristics • Structural Elements • Types • Connective Tissue Proper • Cartilage • Bone • Blood • Develops from mesenchyme • Has a noncellular matrix - plasma

38. Figure 4.8k

39. Nervous Tissue • Neurons • Excitable (electro-chemically) • Brain, spinal cord, nerves, some organs • Cell body = soma • Dendrites receive input • Axon carries output • Neuroglia = glial cells • Support, insulate (electrically), protect • Not excitable

40. Figure 4.9

41. Muscle Tissue • Types of Muscle • By Looks: striated vs smooth • Striated • Skeletal • Cardiac • Smooth • By control: voluntary vs involuntary • Voluntary: skeletal • Involuntary: cardiac, smooth

42. Figure 4.10a

43. Figure 4.10b

44. Figure 4.10c

45. Covering and Lining Membranes • Cutaneous membrane (Skin) • “largest organ”; epidermis over dermis; dry; ch. 5 • Mucous membranes (mucosae) • Line body cavities that connect to outside; wet • Simple columnar or stratified squamous epithelium over lamina propria (loose areolar conn. tiss.) • Often adapted for absorption & secretion • Some but not all secrete mucus • Serous membranes (serosae) • In ventral body cavities: thorax, abdominopelvic • Have inner (visceral) & outer (parietal) layers

46. Figure 4.11

47. Figure 4.11

48. Minor skin wound repair: regeneration and fibrosis Blood clot in incised wound Regenerating epithelium Scab Regenerated epithelium Epidermis Area of granulation tissue ingrowth Vein Fibroblast Macrophage Migrating white blood cell Inflammatory chemicals Artery Fibrosed area Fig. 4.12 Organization restores the blood supply: • The clot is replaced by granulation tissue, which restores the vascular supply. • Fibroblasts produce collagen fibers thatbridge the gap. • Macrophages phagocytize cell debris. • Surface epithelial cells multiply and migrate over the granulation tissue. Inflammation sets the stage: • Severed blood vessels bleed andinflammatory chemicals are released. • Local blood vessels become more permeable, allowing white blood cells,fluid, clotting proteins and other plasma proteins to seep into the injured area. • Clotting occurs; surface dries andforms a scab. 2 1 Regeneration and fibrosis effect permanent repair: • The fibrosed area matures and contracts; the epithelium thickens. • A fully regenerated epithelium withan underlying area of scar tissueresults. 3

49. Where it comes from: embryonic germ layersectoderm, mesoderm, endoderm(outer, middle, inner) 16-day-old embryo (dorsal surface view, cephalic end up, length 1 mm) Muscle and connective tissue (mostly from mesoderm) Ectoderm Mesoderm Nervous tissue (from ectoderm) Endoderm Epithelium Figure 4.13 See also Medical Embryology, 4thed, Langman, 1981.