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Glandular Epithelia: Description, Functions, and Presence

This chapter provides a detailed description of various types of glandular epithelia, including stratified squamous, stratified cuboidal, stratified columnar, transitional, endocrine, and exocrine glands. It explores their functions and presence in the body.

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Glandular Epithelia: Description, Functions, and Presence

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  1. CHAPTER 4 PART 2 STRATIFIED GLANDULAR

  2. DESCRIPTION FUNCTIONS PRESENCE Figure 4.2e

  3. ... with keratin (keratinized)… DRY

  4. KERATINIZED STRATIFIED SQUAMOUS

  5. DRY

  6. moist

  7. Stratified squamous epithelium

  8. ... without keratin (nonkeratinized)… MOIST

  9. Stratified Cuboidal E.T.

  10. Stratified Cuboidal E.T.

  11. Stratified Columnar E.T. • Several cell layers with cuboidal basal cells and columnar superficial cells • protection and secretion Figure 4.2f

  12. Transitional E.T. DESCRIPTION FUNCTIONS PRESENCE Figure 4.2g

  13. Transitional epithelium

  14. ... when the urinary bladder is full

  15. GLANDULAR EPITHELIA

  16. Glandular Epithelia • A gland is one or more cells that makes and secretes an aqueous fluid • Classified by: • Type of product release – • number of cells forming the gland

  17. Endocrine Glands (-crine: to secrete) • Ductless glands that secrete hormones (exocytosis) into blood or lymph. They travel to a target cell. • Target cell secretions include:

  18. Exocrine Glands • More numerous than endocrine glands • Secrete their products onto body surfaces (skin) or into body cavities • Examples include: • Unicellular exocrine – goblet cell • Multicellular exocrine - have a duct and secretory unit

  19. Goblet cell

  20. Multicellular Exocrine Glands • Classified according to: • Duct type • Structure of their secretory units Figure 4.3

  21. Structural Classification of Multicellular Exocrine Glands Figure 4.4a-d

  22. Structural Classification of Multicellular Exocrine Glands Figure 4.4e-g

  23. Modes of Secretion • Merocrine – “exocytosis” • Holocrine – “apoptosis” Figure 4.5

  24. Merocrine secretion

  25. Merocrine secretion • corresponds to the process of exocytosis. Vesicles open onto the surface of the cell, and the secretory product is discharged from the cell without any further loss of cell substance. Most glands – salivary, pancreas (enzymes), eccrine sweat

  26. Holocrinesecretion designates the breakdown and discharge of the entire secretory cell. It is only seen in the sebaceous glands of the skin.

  27. Apocrine secretion • designates part of the apical cytoplasm of the cells is lost together with the secretory product. The continuity of the plasma membrane is restored by the fusion of the broken edges of the membrane, and the cell is able to accumulate the secretory product anew. This mechanism was thought to be used by apocrine sweat glands, the mammary glands and the prostate.

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