mahahaponerityksenä

Mahahaponerityksenä, often referred to as gastric acid secretion, is a physiological process involving the production and release of hydrochloric acid (HCl) by the parietal cells located in the stomach lining. This acidic environment plays a crucial role in digestion, primarily by activating pepsinogen into pepsin, an enzyme essential for protein breakdown. The low pH also helps in sterilizing ingested food, killing harmful bacteria and other pathogens.

The regulation of gastric acid secretion is a complex interplay of neural, hormonal, and paracrine signals. The cephalic phase, triggered by the sight, smell, or thought of food, initiates a neural response via the vagus nerve, stimulating parietal cells. The gastric phase, initiated by the presence of food in the stomach, involves the release of gastrin, a hormone that further enhances acid secretion. Histamine, released from enterochromaffin-like (ECL) cells in the stomach wall, also acts as a potent stimulator of parietal cells. Conversely, somatostatin and prostaglandins act as inhibitors, reducing acid output.

Disruptions in the normal regulation of gastric acid secretion can lead to various gastrointestinal disorders. Excessive acid production or impaired mucosal defense can result in conditions like peptic ulcers, gastroesophageal reflux disease (GERD), and Zollinger-Ellison syndrome. Conversely, insufficient acid production, known as hypochlorhydria or achlorhydria, can impair nutrient absorption, particularly of vitamin B12 and iron, and may increase susceptibility to certain infections. The balance of gastric acid secretion is therefore vital for maintaining digestive health.