1 / 35

Epithelial Tissue Types and Connective Tissue Classes

This text provides a detailed description of different types of epithelial tissues, including transitional epithelium and exocrine glands, as well as the classes of connective tissue, such as connective tissue proper and cartilage. It covers the functions, locations, and features of these tissues.

sammyc
Download Presentation

Epithelial Tissue Types and Connective Tissue Classes

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. PART 2 Tissues

  2. Transitional Epithelium • Description • Basal cells usually cuboidal or columnar • Superficial cells dome-shaped or squamous • Function – stretches and permits distension of urinary bladder • Location • Lines • Ureters, urinary bladder • Proximal urethra

  3. Transitional Epithelium Figure 4.3h

  4. Exocrine Glands • Ducts carry products of exocrine glands to epithelial surface • Include the following diverse glands • Mucus-secreting glands • Sweat and oil glands • Salivary glands • Liver and pancreas

  5. Unicellular Exocrine Glands (The Goblet Cell) • Goblet cells produce mucin • Mucin + water  mucus • Protects and lubricates many internal body surfaces • Goblet cells are a unicellular exocrine gland

  6. Goblet Cells Figure 4.5

  7. Multicellular Exocrine Glands • Have two basic parts • Epithelium-walled duct • Secretory unit

  8. Multicellular Exocrine Glands • Classified by structure of duct • Simple • Compound • Categorized by secretory unit • Tubular • Alveolar • Tubuloalveolar

  9. Types of Multicellular Exocrine Glands Figure 4.6

  10. Endocrine Glands • Endocrine glands are ductless glands • Secrete substances directly into bloodstream • Produce molecules called hormones

  11. Lateral Surface Features – Cell Junctions • Factors holding epithelial cells together • Adhesion proteins link plasma membranes of adjacent cells • Contours of adjacent cell membranes • (Like puzzle pieces) • Special cell junctions

  12. Lateral Surface Features – Cell Junctions • Tight junctions (zona occludens) – close off intercellular space • Found at apical region of most epithelial tissues types • Some proteins in plasma membrane of adjacent cells are fused • Prevent certain molecules from passing between cells of epithelial tissue

  13. Tight Junction Figure 4.7a

  14. Lateral Surface Features – Cell Junctions • Adherens junctions (zonula adherens) – anchoring junction • Transmembrane linker proteins attach to actin microfilaments of the cytoskeleton and bind adjacent cells • With tight junctions, form the tight junctional complex around apical lateral borders of epithelial tissues

  15. Lateral Surface Features – Cell Junctions • Desmosomes – two disclike plaques connected across intercellular space • Plaques of adjoining cells are joined by proteins called cadherins • Regulate cell shape/structure by cell-cell interactions • Class of calcium-dependent adhesion molecules

  16. Lateral Surface Features – Cell Junctions • Proteins interdigitate into extracellular space • Intermediate filaments insert into plaques from cytoplasmic side • Also found in the heart

  17. Desmosome Figure 4.7b

  18. Lateral Surface Features – Cell Junctions • Gap junctions – passageway between two adjacent cells • Let small molecules move directly between neighboring cells • Cells are connected by hollow cylinders of protein • Function in intercellular communication

  19. Gap Junction Figure 4.7c

  20. Basal Feature: The Basal Lamina • Noncellular supporting sheet between the ET and the CT deep to it • Consists of proteins secreted by ET cells

  21. Basal Feature: The Basal Lamina • Functions • Acts as a selective filter, determining which molecules from capillaries enter the epithelium • Acts as scaffolding along which regenerating ET cells can migrate • Basal lamina and reticular layers of the underlying CT deep to it form the basement membrane

  22. Epithelial Surface Features • Apical surface features • Microvilli – fingerlike extensions of plasma membrane • Abundant in ET of small intestine and kidney • Maximize surface area across which small molecules enter or leave • Act as stiff knobs that resist abrasion

  23. Epithelial Surface Features • Apical surface features • Cilia – whiplike, highly motile extensions of apical surface membranes • Contains a core of nine pairs of microtubules encircling one middle pair • Axoneme – a set of microtubules • Each pair of microtubules – arranged in a doublet • Microtubules in cilia – arranged similarly to cytoplasmic organelles called centrioles • Movement of cilia – in coordinated waves

  24. A Cilium Figure 4.8

  25. Classes of Connective Tissue • Most diverse and abundant tissue • Main classes • Connective tissue proper • Cartilage • Bone tissue • Blood • Cells separated by large amount of extracellular matrix • Common embryonic origin – mesenchyme • Extracellular matrix is composed of ground substance

  26. Connective Tissue Proper • Has two subclasses • Loose connective tissue • Areolar, adipose, and reticular • Dense connective tissue • Dense irregular, dense regular, and elastic

  27. Classes of Connective Tissue Figure 4.9

  28. Areolar Connective Tissue – A Model Connective Tissue • Areolar connective tissue • Underlies epithelial tissue • Surrounds small nerves and blood vessels • Has structures and functions shared by other CT • Borders all other tissues in the body • Is a “model” connective tissue – why?

  29. Major Functions of Connective Tissue • Structures within areolar CT and function • Support and binding of other tissues • Holding body fluids (interstitial fluid  lymph) • Defending body against infection • Storing nutrients as fat

  30. Areolar Connective Tissue • Fibers provide support • Three types of protein fibers in extracellular matrix • Collagen fibers • Reticular fibers • Elastic fibers • Fibroblasts produce these fibers

  31. Areolar Connective Tissue • Description • Gel-like matrix with all three fiber types • Cells of areolar CT • Fibroblasts, macrophages, mast cells, and white blood cells • Function • Wraps and cushions organs • Holds and conveys tissue fluid • Important role in inflammation

  32. Areolar Connective Tissue • Locations • Widely distributed under epithelia • Packages organs • Surrounds capillaries

  33. Areolar Connective Tissue Figure 4.12b

  34. Areolar Connective Tissue • Tissue fluid (interstitial fluid) • Watery fluid occupying extracellular matrix • Tissue fluid derives from blood • Ground substance • Viscous, spongy part of extracellular matrix • Consists of sugar and protein molecules • Made and secreted by fibroblasts

  35. Areolar Connective Tissue • Main battlefield in fight against infection • Defenders gather at infection sites • Macrophages • Plasma cells • Mast cells • White blood cells • Neutrophils, lymphocytes, and eosinophils

More Related