Page 641 - Atlas of Histology with Functional Correlations

FIGURE 16.14 ■ Pancreatic islet (special preparation). Stain: Gomori chrome

alum hematoxylin and phloxine. High magnification.

FUNCTIONAL CORRELATIONS 16.3 ■

Endocrine Pancreas

The endocrine components of the pancreas are the pancreatic islets (of
Langerhans) that secrete two major hormones that regulate blood glucose

levels and glucose metabolism.

Alpha cells produce the hormone glucagon that is released in response
to low blood glucose levels. Glucagon elevates blood glucose levels by
accelerating the conversion of glycogen, amino acids, and fatty acids in the
liver cells into glucose for release into the bloodstream.

Beta cells produce the hormone insulin, whose release is stimulated by
elevated blood glucose levels after a meal. Insulin lowers blood glucose
levels by accelerating transmembrane transport of glucose into hepatocytes,
muscle cells, and adipose cells. Insulin also accelerates the conversion of

glucose into glycogen in hepatocytes. The effects of insulin on blood glucose
levels are exactly opposite to that of glucagon.

Delta cells secrete the hormone somatostatin. This hormone decreases
and inhibits secretory activities of both alpha (glucagon-secreting) and beta

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