Hovedcellene

Hovedcellene, also known as chief cells, are a type of cell found in the gastric glands of the stomach lining. These cells are primarily responsible for the synthesis and secretion of pepsinogen, the inactive precursor to the enzyme pepsin. Pepsin is crucial for the initial digestion of proteins in the stomach. Hovedcellene also produce gastric lipase, an enzyme that begins the digestion of fats.

The secretion of pepsinogen from hovedcellene is regulated by several factors. Vagal stimulation, the presence of gastrin, and the release of acetylcholine can all stimulate their activity. Conversely, somatostatin and secretin tend to inhibit pepsinogen release. The environment within the stomach also plays a role; as the stomach becomes more acidic, pepsinogen is converted to its active form, pepsin.

Morphologically, hovedcellene are characterized by their basally located nuclei and abundant rough endoplasmic reticulum, which is indicative of their high protein synthesis activity. Their apical cytoplasm contains numerous zymogen granules, which store the pepsinogen. These granules are released by exocytosis in response to appropriate stimuli.

In summary, hovedcellene are essential components of the stomach's digestive machinery, producing enzymes vital for breaking down proteins and fats. Their function is tightly regulated to ensure efficient digestion while protecting the stomach lining.