Histology: Tissues

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Histology: Tissues

  1. 1. 4-1 Histology: The Study of Tissues
  2. 2. 4-2 Tissues and Histology • Tissue Level of Organization – Epithelial – Connective – Muscle – Nervous • Histology: Microscopic Study of Tissues
  3. 3. 4-3 Embryonic Tissue • Germ layers – Endoderm • Inner layer • Forms lining of digestive tract and derivatives – Mesoderm • Middle layer • Forms tissues as muscle, bone, blood vessels – Ectoderm • Outer layer • Forms skin and neuroectoderm
  4. 4. 4-4 Epithelium Characteristics • Consists almost entirely of cells • Covers body surfaces and forms glands • Has free and basal surface • Specialized cell contacts • Avascular • Undergoes mitosis
  5. 5. 4-5 Functions of Epithelia • Protecting underlying structures • Acting as barriers • Permitting the passage of substances • Secreting substances • Absorbing substances
  6. 6. 4-6 Classification of Epithelium • Simple – Squamous, cuboidal, columnar • Stratified – Squamous, cuboidal, columnar • Pseudostratified – columnar • Transitional – Cuboidal to columnar when not stretched and squamouslike when stretched
  7. 7. 4-7 Types of Epithelium
  8. 8. 4-8 Types of Epithelium
  9. 9. 4-9 Types of Epithelium
  10. 10. 4-10 Types of Epithelium
  11. 11. 4-11 Types of Epithelium
  12. 12. 4-12 Types of Epithelium
  13. 13. 4-13 Types of Epithelium
  14. 14. 4-14 Types of Epithelium
  15. 15. 4-15 Functional Characteristics • Cell layers and shapes – Diffusion, Filtration, Secretion, Absorption, Protection • Cell surfaces – Microvilli: Increase surface area absorption or secretion – Cilia: Move materials across cell surface • Cell connections – Desmosomes, tight, gap • Glands – Exocrine: Have ducts – Endocrine: Have no ducts
  16. 16. 4-16 Cell Connections • Functions – Bind cells together – Form permeability layer – Intercellular communication • Types – Desmosomes – Tight – Gap
  17. 17. 4-17 Exocrine Glands • Unicellular – Goblet cells
  18. 18. 4-18 Multicellular Exocrine Glands
  19. 19. 4-19 Exocrine Glands and Secretion Types • Merocrine – Sweat glands • Apocrine – Mammary glands • Holocrine – Sebaceous glands
  20. 20. 4-20 Connective Tissue • Abundant • Consists of cell separated by extracellular matrix • Diverse • Performs variety of important functions
  21. 21. 4-21 Functions of Connective Tissue • Enclosing and separating as capsules around organs • Connecting tissues to one another as tendons and ligaments • Supporting and moving as bones • Storing as fat • Cushioning and insulating as fat • Transporting as blood • Protecting as cells of the immune system
  22. 22. 4-22 Connective Tissue Cells • Specialized cells produce the extracellular matrix – Suffixes • -blasts: create the matrix • -cytes: maintain the matrix • -clasts: break the matrix down for remodeling • Adipose or fat cells • Mast cells that contain heparin and histamine • White blood cells that respond to injury or infection • Macrophages that phagocytize or provide protection • Stem cells
  23. 23. 4-23 Extracellular Matrix • Components – Protein fibers • Collagen which is most common protein in body • Reticular fill spaces between tissues and organs • Elastic returns to its original shape after distension or compression – Ground substance • Shapeless background – Fluid
  24. 24. 4-24 Connective Tissue Categories • Embryonic or mesenchyme • Adult – Loose – Dense – Connective tissue with special properties – Cartilage – Bone – Blood
  25. 25. 4-25 Loose Connective Tissue • Also known as areolar tissue • Loose packing material of most organs and tissues • Attaches skin to underlying tissues • Contains collagen, reticular, elastic fibers and variety of cells
  26. 26. 4-26 Dense Connective Tissue • Dense regular – Has abundant collagen fibers • Tendons: Connect muscles to bones • Ligaments: Connect bones to bones • Dense regular elastic • Ligaments in vocal folds • Dense irregular • Scars • Dense irregular collagenous • Forms most of skin dermis • Dense irregular elastic • In walls of elastic arteries
  27. 27. 4-27 Dense Regular Connective Tissue
  28. 28. 4-28 Dense Irregular Connective Tissue
  29. 29. 4-29 Connective Tissue with Special Properties • Adipose tissue – Consists of adipocytes – Types • Yellow (white) – most abundant, white at birth and yellows with age • Brown – found only in specific areas of body as axillae, neck and near kidneys • Reticular tissue – Forms framework of lymphatic tissue – Characterized by network of fibers and cells
  30. 30. 4-30 Adipose Tissue
  31. 31. 4-31 Reticular Tissue
  32. 32. 4-32 Cartilage • Composed of chondrocytes located in spaces called lacunae • Next to bone firmest structure in body • Types of cartilage – Hyaline – Fibrocartilage – Elastic
  33. 33. 4-33 Hyaline Cartilage • Found in areas for strong support and some flexibility – Rib cage and cartilage in trachea and bronchi • Forms most of skeleton before replaced by bone in embryo • Involved in growth that increases bone length
  34. 34. 4-34 Fibrocartilage • Slightly compressible and very tough • Found in areas of body where a great deal of pressure is applied to joints – Knee, jaw, between vertebrae
  35. 35. 4-35 Elastic Cartilage • Rigid but elastic properties – External ears, epiglottis
  36. 36. 4-36 Bone • Hard connective tissue that consists of living cells and mineralized matrix • Organic and inorganic • Types – Cancellous or spongy bone – Compact bone
  37. 37. 4-37 Bone
  38. 38. 4-38 Blood • Matrix between the cells is liquid • Hemopoietic tissue – Forms blood cells – Found in bone marrow • Yellow • Red
  39. 39. 4-39 Bone Marrow
  40. 40. 4-40 Muscle Tissue • Characteristics – Contracts or shortens with force – Moves entire body and pumps blood • Types – Skeletal • Striated and voluntary – Cardiac • Striated and involuntary – Smooth • Nonstriated and involuntary
  41. 41. 4-41 Skeletal Muscle
  42. 42. 4-42 Cardiac Muscle
  43. 43. 4-43 Smooth Muscle
  44. 44. 4-44 Nervous Tissue • Found in brain, spinal cord and nerves • Ability to produce action potentials • Cells – Nerve cells or neurons • Consist of dendrites, cell body, axons • Consist of multipolar, bipolar, unipolar – Neuroglia or support cells
  45. 45. 4-45 Neurons
  46. 46. 4-46 Neuroglia

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