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Tissues and a Introduction to the Epithelium

Tissues and a Introduction to the Epithelium. Levels of Organization. atoms→molecules→organelles→cells →tissues. In the body, tissues can be classified into the following functions: Epithelial – cover 1 Connective – support 2 Movement – muscle 3 Control – nervous 4.

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Tissues and a Introduction to the Epithelium

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  1. Tissues and a Introduction to the Epithelium

  2. Levels of Organization atoms→molecules→organelles→cells →tissues

  3. In the body, tissues can be classified into the following functions: Epithelial – cover 1 Connective – support 2 Movement – muscle 3 Control – nervous 4

  4. Epithelial Tissues • Epithelial cells can be classified into 2 types, those that cover surfaces and cavities and those that form a glandular function.

  5. Epithelial tissues have the following functions: • Protection • Absorption • Filtration • Excretion • Secretion • Sensory Reception

  6. Characteristics of epithelial tissues: • Epithelial cells have an upper or free surface.

  7. Characteristics of epithelial tissues: • Epithelial cells have an upper or free surface. • This is known as the Apical Surface

  8. Polarity • The apical surface can be modified by microvilli or cilia. • Microvilli are seen with cells associated with absorption.

  9. Polarity • The microvilli can be so thick that it can be described as a brush boarder.

  10. Polarity • The bottom side of the epithelial cell is called the basal surface. • It is supported by a non cellular, adhesive sheet called the basal lamina.

  11. Epithelial cells have contact with each other. These lateral contacts are the desmosomes and tight junctions. Specialized Contacts

  12. Specialized Contacts • The tight junction forms an impermeable junction between each cell and thus prevents diffusion between the cells.

  13. Specialized Contacts • The desmosomes help hold the cell’s shape with anchoring junctions scattered between each cell.

  14. Connective Tissue Support • The basilar surface attached to a connective tissue net work. • There are two parts. The first is the basal lamina secreted from the epithelial cell. • The second is the reticular lamina that is made of collagen which is produced by fibroblasts.

  15. Connective Tissue Support • Together the basal lamina and reticular lamina form the basement membrane. • This forms the foundations which anchor the epithelial cells.

  16. Avascular but Innervated • Epithelial cells do not have a blood supply • They depend on diffusion for the delivery of nutrients and removal of wastes. • They do have a nerve supply, innervated, for sensory function.

  17. Regeneration • Do to their protective function; epithelial cells need to be continually replaced. • Mitotic figures are not uncommon.

  18. Cancer • Many cancers are of epithelial origin. • The greater the mitotic index, the greater the chance of cancer.

  19. Cancer Types

  20. Cancer Types • Lung cancer caused by smoking typically starts in the bronchial epithelium

  21. 1 Picture & 1000 words

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