Regulation of Gastric Secretions

Gastric juice is produced continuously, but the rate varies considerably from time to time and is controlled both neurally and hormonally. More specifically, within the gastric glands, specialized cells closely associated with the parietal cells secrete the hormone somatostatin, which inhibits acid secretion. However, acetylcholine (ACh) released from nerve endings in response to parasympathetic impulses arriving on the vagus nerves suppresses the secretion of somatostatin and stimulates the gastric glands to secrete large amounts of gastric juice, which is rich in hydrochloric acid and pepsinogen. These parasympathetic impulses also stimulate certain stomach cells, mainly in the pyloric region, to release a peptide hormone called gastrin, which increases the secretory activity of gastric glands (fig. 17.21). Furthermore, parasympathetic impulses and gastrin promote release of histamine from gastric mucosal cells, which, in turn, stimulates additional gastric secretion.

A light micrograph of cells associated with the gastric glands (50x micrograph enlarged to 100x).

Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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