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Chapter 5: Tissues!

Chapter 5: Tissues!. Histology. The study of tissues =. There are four major tissue types in the body: Epithelial Muscle Nerve Connective. Epithelial Tissue. A) Locations. covers all body surfaces – inside and outside forms inner lining of body cavities and organs. B) Structure.

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Chapter 5: Tissues!

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  1. Chapter 5: Tissues!

  2. Histology The study of tissues =

  3. There are four major tissue types in the body: • Epithelial • Muscle • Nerve • Connective

  4. Epithelial Tissue

  5. A) Locations • covers all body surfaces – inside and outside • forms inner lining of body cavities and organs

  6. B) Structure • Damaged cells are continually replaced. • Cells are tightly packed and often attached to one another by desmosomes & tight junctions • Substances readily pass between cells • e.g. gap junctions

  7. C) Functions of Epithelial Tissue • Protection • Absorption • Filtration • Secretion

  8. D) Types of Epithelial Tissues

  9. 1. Simple Squamous Epithelial • Absorption • diffusion • filtration

  10. e.g. air sacs (alveoli) of lungs

  11. Endothelium

  12. 2. Simple Cuboidal Epithelial

  13. Absorption • Secretion • liver • thyroid • kidney tubules Cross-Section of a kidney tubule

  14. 3. Simple Columnar Epithelial • Absorption • Movement (e.g. egg and embryo move along uterine tube)—by cilia at cell surface • Secretion (e.g. goblet cells in the large intestine secrete mucus to ease the passage of feces.)

  15. lining of the gallbladder

  16. Goblet cell

  17. 4. Stratified Squamous Epithelium • multi-layered protection

  18. protects against mechanical abrasion, water loss, and pathogen entry e.g. sole of the foot

  19. 5. Stratified Cuboidal Epithelium • Protection e.g. sweat gland ducts, mammary glands

  20. e.g. ovarian follicle (cells surround an oocyte)

  21. 6. Pseudostratified Columnar Epithelium • looks multi-layered, but it’s NOT! • cells are of varying heights , and nuclei are at several levels. • goblet cells present • often ciliated at the surface

  22. e.g. respiratory tract

  23. Here, we have pathogens traveling down the pharynx trying to attack the surface cells. How can they be repelled???

  24. Ahhh!!! It’s so sticky and slimy! The mucosal cells lining the trachea release a flood of mucus, trapping the pathogens!

  25. blub, blub . . . . The cilia successfully sweep the pathogens up and away!

  26. 7. Transitional Epithelium • resembles stratified squamous epithelium, but surface cells are rounded and often bulge above surface (dome-shaped)

  27. distensible e.g. urinary bladder and tract lining

  28. Connective Tissue • found throughout the body, and as parts of various organs • composed of connective tissue cells + extracellular matrix • extracellular matrix = fibers + ground substance [fluid-solid]

  29. Functions: • protects internal organs, provide support, connect organs together • provide framework • fill spaces • produce blood cells • provide immune protection • tissue repair

  30. Composition 1. Fibers Collagen Fibers as seen with a scanning electron microscope

  31. a) collagenous fibers • interwoven strands of collagen (protein) • most abundant protein • thick fibers with great tensile strength • white & wavy appearance e.g. tendons, ligaments, deep layer of the skin Close-up of a single fiber

  32. b) elastic fibers • made of elastin protein • coiled structure to stretch and snap back like a rubber band • e.g. lungs, arteries, and skin

  33. c) reticular fibers • very thin collagen fibers that branch extensively • form frameworks for organs e.g. liver

  34. 2. Ground substance • Gelatinous material between the connective tissue cells and fibers [fluid to semi-solid to solid]

  35. Types of Connective Tissues

  36. A) Fibrous connective tissues

  37. a) areolar connective tissue 1) Loose Connective Tissue • Loose arrangement of all 3 fiber types

  38. : e.g. under epithelia, surrounding blood vessels, nerves, between muscles

  39. b) reticular tissue • loose network of reticular fibers • form a scaffold-like framework for lymphatic organs. e.g. lymph nodes, spleen

  40. c) adipose tissue • adipocytes – large, clear cells with thin margins. • Subcutaneous fat beneath skin, breast, heart, eyes

  41. Functions of adipose tissue: • Energy storage • Thermal insulation • Shock absorption • Protective cushioning

  42. a) Dense Regular CT 2. Dense Connective Tissue • Densely packed, parallel, often wavy collagenous fibers • Little open space e.g. ligaments bind bone to other bones tendons attach skeletal muscles to bone

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