Tissues: The Living Fabric

• Function• Location– Basal cells are cuboidal or columnar– Surface cells are dome-shaped or squamouslike depending on the degree of stretch of theorgan– Allows distention of urinary organs– Ureters, bladder and parts of urethra• Glandular Epithelia• Glands make and secrete watery substances referred to as secretions• Two types exist– Endocrine (ductless) glands• Release secretions directly into the blood stream or lymph– Exocrine glands (glands have ducts)• Release secretions onto body surface or into body cavities• Classification of Exocrine Glands• Unicellular– Goblet cell• Multicellular– Have a secretory portion (acinus) and duct• Structurally classified as simple (straight duct) or compound (branchedduct)• Classified based on secretory units as tubular (tube-shaped acinus), alveolar(flasklike acinus), and tubuloalveolar if both are present.– Figure 4.4b Goblet cell (unicellular exocrine gland).• Multicellular– Classified based on secretory mode as:• Merocrine – secretes by exocytosis• Holocrine - secretory cells rupture to release secretion• Apocrine – apical portion of secretory cell ruptures to release secretion