Question 1

What is the main difference between unicellular and multicellular exocrine glands?

Accepted Answer

Unicellular exocrine glands are individual secretory cells, such as goblet cells in the intestinal epithelium, that directly secrete mucin onto epithelial surfaces. Multicellular exocrine glands consist of groups of cells forming secretory units with ducts that deliver secretions to the surface. Multicellular glands are more complex and can be further classified based on duct and secretory unit morphology.

Question 2

How are multicellular exocrine glands classified based on duct structure?

Accepted Answer

Multicellular exocrine glands are classified as simple glands with unbranched ducts or compound glands with branched ducts. Simple glands have a single continuous duct, while compound glands have multiple branched ducts that deliver secretions from various secretory units to the epithelial surface.

Question 3

What are tubular glands and where are they found?

Accepted Answer

Tubular glands contain secretory units shaped as straight or coiled tubes. Examples include intestinal glands and sweat glands, which are simple tubular glands with a single duct, and gastric glands, which are simple branched tubular glands. Compound tubular glands are found in organs like the testes and male reproductive system.

Question 4

What distinguishes alveolar glands from tubular glands?

Accepted Answer

Alveolar or acinar glands have secretory units shaped as hollow sacs, unlike tubular glands with tube-shaped units. Sebaceous glands are simple branched alveolar glands, while mammary glands are compound alveolar glands with secretory sacs connected to branched ducts. Some glands like salivary glands contain both tubular and alveolar sacs.

Question 5

What is the function of goblet cells in the intestinal epithelium?

Accepted Answer

Goblet cells are unicellular exocrine glands that secrete mucin, a complex glycoprotein, onto the epithelial surface of the small and large intestines. This mucin forms a slimy protective mucus coat that lubricates and protects the intestinal lining from mechanical damage and pathogens.

Question 6

How do simple and compound tubuloalveolar glands differ from other multicellular glands?

Accepted Answer

Compound tubuloalveolar glands contain both tubular and alveolar secretory sacs connected to branched ducts, combining features of both gland types. Salivary glands exemplify this structure. This mixed morphology allows these glands to produce diverse secretions more efficiently than glands with only one secretory unit type.

Question 7

What role do ducts play in multicellular exocrine gland function?

Accepted Answer

Ducts in multicellular exocrine glands transport secretions produced by secretory units to the epithelial surface or organ lumen. The duct structure—whether simple and unbranched or compound and branched—determines how efficiently secretions are delivered and influences the gland's overall secretory capacity and function.

غدة خارجية الإفراز: الغدد ذات الخلية الواحدة و الغدد ذات الخلايا المتعددة

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