1 / 63

Tissues: The living fabric

Tissues: The living fabric. Ch 4 a Epithelial Tissue. Tissues. Histology = Study of tissues Tissue = Groups of cells similar in structure and function The four types of tissues Epithelial - covering Connective - support Muscle - movement Nerve - control. Epithelial Tissue. 2 types

tarala
Download Presentation

Tissues: The living fabric

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. Tissues: The living fabric Ch 4 a Epithelial Tissue

  2. Tissues • Histology = Study of tissues • Tissue = Groups of cells similar in structure and function • The four types of tissues • Epithelial - covering • Connective - support • Muscle - movement • Nerve - control

  3. Epithelial Tissue • 2 types • Covering and lining epithelium • Glandular epithelium

  4. Epithelial TissueCovering and lining epithelium

  5. Epithelial Tissue • A sheet of cells that covers a body surface or lines a body cavity • Forms boundaries between different environments

  6. Epithelial Tissue Functions • Protection • Absorption • Filtration • Excretion • Secretion (from glands) • Sensory reception

  7. Characteristics of Epithelial Tissue • Cellularity – composed almost entirely of cells • Very little extracellular material • Special contacts – form continuous sheets held together by tight junctions and desmosomes

  8. Characteristics of Epithelial Tissue • Polarity – apical and basal surfaces • Apical = free upper surface exposed to exterior of body or cavity (some are slick, some have cilia, most have microvilli) • Basal = lower surface attached

  9. Characteristics of Epithelial Tissue • Basal surface attached to basement membrane • basal laminae – thin, adhesive, non-cellular • reticular laminae – fine network of collagen fibers belonging to the connective tissue underneath, non-cellular

  10. Characteristics of Epithelial Tissue • All epithelial tissue are supported by and rest upon connective tissue

  11. Characteristics of Epithelial Tissue • Avascular but innervated – contains no blood vessels but supplied by nerve fibers – nourished by diffusion • Regenerative – rapidly replaces lost cells by cell division

  12. Classification of Epithelia • Simple • stratified Figure 4.1a

  13. Classification of Epithelia • Squamous • Cuboidal • Columnar Figure 4.1b

  14. Epithelia: Simple Squamous • Single layer of flattened cells with disc-shaped nuclei and sparse cytoplasm

  15. Epithelia: Simple Squamous • Functions • Diffusion and filtration • Provide a slick, friction-reducing lining in lymphatic and cardiovascular systems • Present in the kidneys, lungs, lining of heart, blood vessels, lymphatic vessels

  16. Epithelia: Simple Squamous Figure 4.2a

  17. Epithelia: Simple Cuboidal • Single layer of cubelike cells with large, spherical central nuclei • Function in secretion and absorption • Present in kidney tubules, ducts and secretory portions of small glands, and ovary surface

  18. Epithelia: Simple Cuboidal • Single layer of cubelike cells with large, spherical central nuclei • Function in secretion and absorption • Present in kidney tubules, ducts and secretory portions of small glands, and ovary surface Figure 4.2b

  19. Epithelia: Simple Columnar • Single layer of tall cells with oval nuclei; many contain cilia • Goblet cells are often found in this layer • Cells that secrete a protective lubricating mucus • Function in absorption and secretion

  20. Epithelia: Simple Columnar • Nonciliated type line digestive tract and gallbladder • Ciliated type line small bronchi, uterine tubes, and some regions of the uterus • Cilia help move substances through internal passageways

  21. Epithelia: Simple Columnar Figure 4.2c

  22. Epithelia: Pseudostratified Columnar • Single layer of cells with different heights; some do not reach the free surface • Nuclei are seen at different layers

  23. Epithelia: Pseudostratified Columnar • Function in secretion and propulsion of mucus • Present in the male sperm-carrying ducts (nonciliated) and trachea (ciliated)

  24. Epithelia: Pseudostratified Columnar • Single layer of cells with different heights; some do not reach the free surface • Nuclei are seen at different layers • Function in secretion and propulsion of mucus • Present in the male sperm-carrying ducts (nonciliated) and trachea (ciliated) Figure 4.2d

  25. Epithelia: Stratified Squamous • Thick membrane composed of several layers of cells • Function in protection of underlying areas subjected to abrasion

  26. Epithelia: Stratified Squamous • Forms the external part of the skin’s epidermis (keratinized cells), and linings of the esophagus, mouth, and vagina (nonkeratinized cells)

  27. Epithelia: Stratified Squamous • Thick membrane composed of several layers of cells • Function in protection of underlying areas subjected to abrasion • Forms the external part of the skin’s epidermis (keratinized cells), and linings of the esophagus, mouth, and vagina (nonkeratinized cells) Figure 4.2e

  28. Epithelia: Stratified Cuboidal • Stratified cuboidal • Quite rare in the body • Found in some sweat and mammary glands • Typically two cell layers thick

  29. Epithelia: Stratified Columnar • Stratified columnar • Limited distribution in the body • Found in the pharynx, male urethra, and lining some glandular ducts • Also occurs at transition areas between two other types of epithelia

  30. Epithelia: Transitional • Several cell layers, basal cells are cuboidal, surface cells are dome shaped • Stretches to permit the distension of the urinary bladder • Lines the urinary bladder, ureters, and part of the urethra

  31. Epithelia: Transitional • Several cell layers, basal cells are cuboidal, surface cells are dome shaped • Stretches to permit the distension of the urinary bladder • Lines the urinary bladder, ureters, and part of the urethra Figure 4.2f

  32. Epithelial TissueGlandular Epithelia

  33. Epithelia: Glandular • A gland is one or more cells that makes and secretes an aqueous fluid

  34. Epithelia: Glandular • Glands Classified by: • Site of product release – • Endocrine (internally secreting) or Exocrine (externally secreting) • Relative number of cells forming the gland – • Unicellular (one cell) & Multicellular (many cells)

  35. Endocrine Glands • Ductless glands that produce hormones • Secretions include amino acids, proteins, glycoproteins, and steroids

  36. Exocrine Glands • More numerous than endocrine glands • Secrete their products onto body surfaces (skin) or into body cavities

  37. Exocrine Glands • Examples include mucous, sweat, oil, and salivary glands, the liver (which secrets bile), the pancreas (which secrets enzymes) and others

  38. Unicellular Exocrine Glands • The only important unicellular exocrine gland is the goblet cell • Found in linings of intestinal and respiratory tracts • Secrets mucus

  39. Multicellular Exocrine Glands • Multicellular exocrine glands are composed of a duct and secretory unit • Classified according to: • Simple or compound duct type • Structure of their secretory units

  40. Structural Classification of Multicellular Exocrine Glands Figure 4.3a-d

  41. Structural Classification of Multicellular Exocrine Glands Figure 4.3e-g

  42. Modes of Secretion • Merocrine – products are secreted by exocytosis (e.g., pancreas, sweat, and salivary glands) • Holocrine – products are secreted by the rupture of gland cells (e.g., sebaceous glands)

  43. Modes of Secretion Merocrine Holocrine Figure 4.4

  44. http://www.youtube.com/watch?v=7z2vYr5YjD8

  45. Simple cuboidal epithelium

  46. Simple cuboidal epithelium

More Related