Chapter 4
Question 33-Define gland, differentiate between exocrine and endocrine glands, and multicellular and unicellular glands.

1) Gland-Consists of one or more cells that make and secrete a particular product
2) Endocrine glands-They will eventually lose their ducts, and produce hormones, which are regulatory chemicals that are secreted by exocytosis directly into the extracellular space. Most endocrine glands have a lot of cells. The ones that don't are individual hormone producing cells, and scattered around the digestive tract.
Exocrine glands-There are many more exocrine glands than endocrine glands, but some of the products are the same. All exocrine glands excrete their products onto body surfaces or into body cavities. The glands could be anything like mucus, sweat, oil, and salivary glands. The liver has bile, and the pancreas has digestive glands.
3) Unicellular glands have something called a goblet cell. These cells are all around the epithelial linings of the intestinal and respiratory tracts. In humans all of these glands produce mucin a complex glycoprotein that dissolves in water when secreted.
Multicellular exocrine glands-They are more structurally complex. They have two parts, one which is an epithelium duct and a secretory unit consisting of secretory cells. These glands are either simple or compound. Simple ones have an unbranched duct, and compound ducts have branched duct. One way the exocrine gland secrets is by merocrine glands which secrete by exocytosis.The second way is by holocrine glands which store their products until they rupture.