TISSUES

1. TISSUES UNIT 3

2. I. Types of Tissues • Epithelial tissue • Covers body surfaces • Lines hollow organs, body cavities and ducts • Forms glands

3. Connective tissue • Protects and supports the body and its organs • Bind organs together • Store energy reserves as fat • Help provide immunity to disease-causing organisms

4. Muscular tissue • Generates the physical force needed to make body structures move

5. Nervous tissue • Detects changes in a variety of conditions inside and outside the body • Responds to changes by generating nerve impulses • Nerve tissue in the brain helps maintain homeostasis

7. 1. EPITHELIAL TISSUE • Consists of cells arranged in continuous sheets • in either single or multiple layers • There is little intercellular space between adjacent cells

8. A. Epithelial surfaces • Apical surface: the free surface that faces the “outside” The most superficial layer

9. Lateral surface: faces the adjacent cells • Basal surface: opposite the apical surface adhered to extracellular materials The deepest layer

11. B. Types of Epithelium • Covering and lining: form the outer covering of the skin and some internal organs also forms the inner lining of blood vessels, ducts and body cavities and the interior of many organ systems

12. a. Classification of covering and lining cells • C & L cells are classified according to two characteristics: • Arrangement of cells into layers • Cell shape

13. i. Arrangement in layers • Arranged in one or more layers depending on the function performed

14. Simple Epithelium • A single layer of cells that function in diffusion, osmosis, filtration, secretion (production and release) and absorption (intake)

15. Stratified Epithelium • Two or more layers of cells that protect underlying tissues • Found in locations of considerable wear and tear

16. ii. Cell shape • Squamous cells: thin and arranged like floor tiles allowing for the rapid movement of substances through them occur in cells in which diffusion or infiltration occurs

17. Cuboidal cells • Are as tall as they are wide • Shaped like cubes…or hexagons • May have microvilli on apical surface • Function in secretion or absorption

18. Columnar cells • Taller than they are wide • Protect underlying tissue • Apical surface may have microvilli or cilia • Function in secretion or absorption

19. Transitional cells • Cells that change shape from cuboidal to flat or visa versa • This occurs as organs stretch or collapse

24. 2. Glandular Epithelium constitutes the secreting portion of glands such as: thyroid, adrenal and sweat glands.

25. 2. CONNECTIVE TISSUE • One of the most abundant and widely distributed tissues • Performs a variety of functions: • binds together, supports and strengthens other body tissues

26. protects and insulates internal organs • compartmentalizes structures such as skeletal muscles • is the major site of immune responses • is the major transport system (as blood is a fluid connective tissue)

27. Consists of cells and an extracellular matrix which is located between the widely spaced cells and consists of protein fibers and ground substance (the stuff between the cells and the fibers)

28. The ground substance: • supports cells, • binds cells together • stores water • provides a medium for exchange of materials between the blood and cells

29. The fibers include collagen fibers, elastic fibers and reticular fibers. They strengthen and support ct. • Collagen fibers are found in most types of ct and are made of the protein collagen. This is the most abundant protein in the body!

30. Classification of CT I. Embryonic ct • Mesenchyme (tissue from which all ct arises) • Mucous ct (mainly in the umbilical cord)

31. II. Mature ct A. Loose ct 1. Areolar ct 2. Adipose tissue 3. Reticular ct

32. B. Dense ct 1. dense, regular ct 2. dense, irregular ct 3. elastic ct

33. C. Cartilage 1. Hyaline cartilage 2. Fibrocartilage 3. Elastic cartilage

34. D. Bone tissue E. Liquid ct 1. Blood tissue 2. Lymph

35. Areolar connective tissue is the most widely distributed ct and is the only kind that occurs on an external surface and is the tissue that lines joint cavities • C.T. is usually highly vascular therefore has a rich blood supply

36. An exception is cartilage which is an avascular CT and tendons which are slightly vascular. • All CT have a nerve supply except for cartilage

37. A. TISSUE CELLS • Mesenchymal cells give rise to the all tissue cells • The immature form of tissue cells are • Fibroblasts (CT), chondroblasts (cartilage) and osteoblasts (bone)

38. Immature “blast” cells are able to divide and secrete the matrix of its tissue. • Mature “cyte” cells have a reduced capacity for cell division and are more involved in matrix maintenance

39. 1. Fibroblasts • Large, fat cells with branching processes. • Are the most abundant. • They migrate through the ct and secrete the fibers and ground substance of the matrix

41. 2. Macrophages • Have an irregular shape with short branching projections • Capable of engulfing bacteria and cellular debris by phagocytosis • Some are fixed (remain in one cell) and others wander and gather at the site of infection

43. 3. Plasma cells • Cells that develop from β lymphocytes. • Secrete antibodies that attack or neutralize foreign bodies

45. 4. Mast cells • Abundant along the blood vessels that supply the ct • Produce histamine: dilates blood vessels as an inflammatory response • and heparin: an anticoagulant

47. 5. Adipocytes • Fat cells • Store triglycerides • Found deep beneath the skin…around organs such as the heart and kidneys

48. 6. White Blood Cells • Not normally abundant in ct • Migrate from blood to ct in response to events such as infection, parasitic invasions and allergic reactions

49. B. Cartilage • Endures tension and compression • Tough, but flexible • Provides resilient rigidity to the structures it supports • Heals slowly when injured

50. Three types of cartilage • Hyaline cartilage: most abundant; provides firm support with some pliability Found at: ends of long bones, tip of nose, between ribs and sternum, as a support to the respiratory system