Glossary of Terms & Definitions
Listed Alphabetically - "Z"

Zoellinger Ellison syndrome: A rare disorder caused by a tumor called a gastrinoma, most often occurring in the pancreas. The tumor secretes the hormone gastrin, which causes increased production of gastric acid leading to severe recurrent ulcers of the esophagus, stomach, and the upper portions of the small intestine.

Zygote: A single cell resulting from the union of male and female gametes; the fertilized ovum.