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Lab Exercise 5

Lab Exercise 5. Epithelial and Connective Tissues. Portland Community College BI 231. Tissues. Groups of cells similar in structure and function Each tissue is then further subdivided into categories. All organs are made of a combination of different tissues. The four types of tissues

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Lab Exercise 5

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  1. Lab Exercise 5 Epithelial and Connective Tissues Portland Community College BI 231

  2. Tissues • Groups of cells similar in structure and function • Each tissue is then further subdivided into categories. • All organs are made of a combination of different tissues. • The four types of tissues • Epithelial • Connective • Muscle • Nerve

  3. Epithelium • Covers all body surfaces, inside and out • Is anchored to connective tissue by a layer of glycoproteins and protein fibers called the basal lamina

  4. Epithelial TissueDistinguishing Characteristics • Cellularity: Composed almost entirely of cells • Polarity: apical and basal surfaces (top and a bottom) • Attachment: Supported by connective tissue (basement membrane) • Avascular: Contains no blood vessels: obtains nutrients by diffusion • Regeneration: Rapidly replaces lost cells by cell division

  5. Functions of Epithelia • Protection: Skin • Secretion: glands release secretions • Absorption: Uptake nutrients • Sensory: Taste buds • Filtration: In the kidneys

  6. Classification of Epithelia • First name: • Simple: one layer • Stratified: more than one layer • Second name: • Based on the shape of the top layer of cells • Squamous (flat) • Cuboidal (square) • Columnar (rectangle) • Two additional categories • Transitional • Pseudostratified

  7. Classification of Epithelia

  8. Classification of Epithelia • Squamous • Cuboidal • Columnar

  9. Simple Squamous Epithelium • Single layer of flattened cells with disc-shaped nuclei and sparse cytoplasm

  10. Simple Squamous Epithelium • Top View

  11. Simple Squamous Epithelium

  12. Simple Squamous Epithelium • Functions: • Diffusion • Alveoli in the respiratory system allows for exchange of O2 and CO2 • Filtration • Capillaries allow fluid and other substances out and holds blood cells and proteins in • Lubrication • Secretes lubricating substances in serosae

  13. Simple Cuboidal Epithelium • Single layer of cube like cells with large, spherical central nuclei

  14. Simple Cuboidal Epithelium

  15. Simple Cuboidal Epithelium • Functions: • Secretion • Glands such as the thyroid are composed of simple cuboidal epithelium and secrete hormones ect… • Absorption • In the kidney, the proximal convoluted tubule is composed of simple cuboidal epithelium and reabsorbs water and other nutrients from the filtered fluid

  16. Simple Columnar Epithelium • Single layer of tall cells with oval nuclei toward the basal surface • Goblet cells are often found in this layer

  17. Simple Columnar Epithelium

  18. Simple Columnar Epithelium

  19. Simple Columnar Epithelium • Functions • Secretion • Example: In the stomach, these cells secrete digestive enzymes • Absorption • Example: In the intestine, these cells absorb nutrients

  20. Stratified Squamous Epithelium • Composed of several layers of cells • Top layer flat • Bottom layers any shape • Function in protection of underlying areas subjected to abrasion

  21. Stratified Squamous Epithelium • Non-keratinized • Composed of several layers of cells • Top layer flat • Bottom layers any shape

  22. Stratified Squamous EpitheliumNon-Keratinized

  23. Stratified Squamous EpitheliumNon-Keratinized • Functions • Physical protection against abrasion and pathogens • Non-Keratinized is associated with “moist” areas • Mouth • Throat • Esophagus • Anus • Vagina

  24. Stratified Squamous EpitheliumKeratinized Looks “flakey” on the top

  25. Stratified Squamous EpitheliumKeratinized

  26. Stratified Squamous EpitheliumKeratinized • Functions • Physical Protection • Found only in the epidermis of the skin • Keratin is a protein that helps strengthen the cells against abrasion

  27. Pseudostratified Columnar Epithelium • Single layer of cells with different heights; some do not reach the free surface • Nuclei are seen at different levels • May be ciliated (PCCE) or non-ciliated

  28. Pseudostratified Columnar Epithelium

  29. Pseudostratified Columnar Ciliated Epithelium (PCCE)

  30. Pseudostratified Columnar Ciliated Epithelium (PCCE) • Functions • Protection • Example: Lines the upper respiratory tract. The cilia sweep debris toward the throat • Secretion • Example: May contain goblet cells (unicellular glands) that secrete mucus

  31. Transitional Epithelium • Several cell layers, basal cells are cuboidal • Apical cells are dome shaped when not stretched • Apical cells are flat when stretched • Only found in Urinary System • Functions: • Allows expansion and recoil after stretching

  32. Transitional Epithelium Distended bladder Empty bladder

  33. Stratified Cuboidal and Columnar • Typically two cell layers thick • Rare • Functions: • Secretion • Found in some sweat and mammary glands

  34. Stratified Cuboidal Epithelium

  35. Stratified Cuboidal Epithelium

  36. Stratified Columnar Epithelium • Limited distribution in the body • To tell the difference between this and pseudostratified columnar, look at the nucleus. • The nuclei are lined up in a straight row • Function • Protection • Found in the pharynx, male urethra, lining some glandular ducts, and anus

  37. Stratified Columnar Epithelium

  38. Stratified Columnar Epithelium

  39. Connective Tissue • 4 Types • Connective Tissue Proper • Bone • Blood • Cartilage

  40. Connective Tissue Features • Specialized cells • Matrix: Nonliving material between the cells that makes up most of the volume (ground substance + fibers) • Extracellular fibers • Ground substance: Composed chiefly of interstitial fluid, cell adhesion proteins, and proteoglycans • Specific composition varies between tissues (Blood=fluid, Cartilage=gel like, Bone=Solid)

  41. Connective Tissue Fibers • 3 types of fibers include collagen, elastic and reticular • Collagen Fibers:Fibrous protein molecules • Extremely tough • High tensile strength • Strongest type of fibers in connective tissue.

  42. Connective Tissue Fibers • Elastic Fibers: Form branching networks • Elastin: a rubber like protein that allow it to act like a rubber band and snap back to its original shape after it is stretched • Reticular Fibers:Forming delicate networks • Fine collagenous fibers (with a different chemical structure) branch extensively • Surround small blood vessels and support soft tissue organs

  43. Blast cells • Undifferentiated cells (blast = forming) • Fibroblasts- fount in loose and dense connective tissues (secrete matrix) • Chondroblasts in cartilage • Osteoblasts in bone • Hemocytoblasts in blood • ‘cytes’ are the mature forms

  44. Cells of Connective Tissue Proper • Reticular cells: specialized fibroblasts found in reticular connective tissue • Macrophages: Scavenger cells that engulf pathogens or damaged cells • Adipocytes: Fat cells • Plasma cells: produce antibodies • Mast cells: Stimulate local inflammation: contain histamine and heparin • Leukocytes: WBC involved in immunity

  45. Mesenchyme • Embryonic Connective tissue • Gel-like ground substance with fine protein fibers and immature cells; gives rise to all other connective tissues

  46. Areolar Connective Tissue (Loose) • Gel like matrix • Contains all 3 fiber types • Functions: • Wraps and cushions organs • Holds and conveys tissue fluid • Locations: • Under epithelial tissues • Packages organs • Surrounds capillaries

  47. Areolar Connective Tissue (Loose) Fibroblast Collagen fiber Macrophage Elastic fiber

  48. Adipose Tissue (Loose) • Function: • Storage of lipid molecules • Insulation

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