Expert: John Locke - 4/2/2010

Question
Discuss the validity of the followingg statement:
A tissue contains group of cells where each group has quite a different function

Answer
This statement is essentially true: a tissue comprises a group of cells that share a similar function but with different individual roles. There is some subtlety here that I'd like to describe, and it is most easily seen with an example. Consider the pancreas: there are several distinct cell types within pancreatic tissue, clustered into groups that serve complimentary functions. Nonetheless, it is possible to identify groups of cells that serve quite different functions within the tissue.

The endocrine pancreas produces somatostatin, glucagon, and insulin; these hormones all antagonize each other and are secreted from different cells, but the cells that secrete them are clustered together into small groups. These groups of cells serve the same ultimate purpose--the regulation of blood glucose levels--but arguably have different functions because of the different products they produce. The exocrine pancreas is similar. Acinar cells of the pancreatic ducts produce digestive enzymes, while the centroacinar cells produce bicarbonate. They are serving a common goal (the digestion of food), but with different individual functions. That, I would argue, is the best conceptual way to understand tissue: arrangements of cells that are working toward a common purpose but with a variety of individual functions.