Parietal Cells

Definition

Parietal cells are a type of epithelial cells located in the lining of the stomach. They are responsible for producing hydrochloric acid (HCl) and the intrinsic factor, which are essential for the digestion and absorption of nutrients, particularly vitamin B12.

5 Must Know Facts For Your Next Test

1. Parietal cells contain an extensive network of secretory canaliculi, which increase the surface area for acid secretion.
2. The production of HCl by parietal cells is stimulated by various factors, including histamine, acetylcholine, and gastrin.
3. Parietal cells also secrete bicarbonate ions to help neutralize the acidity of the stomach contents as they move into the small intestine.
4. Impairment of parietal cell function can lead to conditions like achlorhydria (lack of stomach acid) or pernicious anemia (vitamin B12 deficiency).
5. Histamine blockers and proton-pump inhibitors work by targeting the acid-secreting mechanisms of parietal cells to reduce stomach acid production.

Review Questions

• Explain the role of parietal cells in the digestive process and their importance for nutrient absorption.
  • Parietal cells play a crucial role in the digestive process by secreting hydrochloric acid (HCl) and the intrinsic factor. HCl helps break down food, activate digestive enzymes, and create an acidic environment in the stomach, which is essential for the proper digestion and absorption of nutrients. The intrinsic factor secreted by parietal cells is necessary for the absorption of vitamin B12 in the small intestine. Without the proper functioning of parietal cells, conditions like achlorhydria (lack of stomach acid) and pernicious anemia (vitamin B12 deficiency) can develop, leading to various digestive and nutritional problems.
• Describe how histamine blockers and proton-pump inhibitors (PPIs) interact with parietal cells to reduce stomach acid production.
  • Histamine blockers and proton-pump inhibitors (PPIs) target the acid-secreting mechanisms of parietal cells to reduce stomach acid production. Histamine blockers, such as ranitidine and cimetidine, work by inhibiting the action of histamine, which is one of the primary stimulants of acid secretion by parietal cells. PPIs, like omeprazole and esomeprazole, directly block the proton pumps (H+/K+ ATPase) within parietal cells, preventing the final step in the production of hydrochloric acid. By reducing the amount of stomach acid, these medications help alleviate conditions like gastroesophageal reflux disease (GERD), peptic ulcers, and other acid-related disorders.
• Analyze the potential consequences of impaired parietal cell function and the importance of maintaining their proper functioning for overall digestive health.
  • Impairment of parietal cell function can lead to several serious health consequences. Reduced or absent acid secretion by parietal cells, a condition known as achlorhydria, can result in inadequate breakdown of food, impaired activation of digestive enzymes, and an increased risk of bacterial overgrowth in the small intestine. Additionally, the lack of intrinsic factor secreted by parietal cells can cause pernicious anemia, a type of megaloblastic anemia due to vitamin B12 deficiency. This can lead to neurological symptoms, such as numbness and tingling in the extremities, as well as digestive issues and an increased risk of certain infections. Maintaining the proper functioning of parietal cells is crucial for overall digestive health, nutrient absorption, and the prevention of various gastrointestinal disorders. Therapies that target parietal cell function, such as histamine blockers and proton-pump inhibitors, can help manage acid-related conditions and support optimal digestive function.

Related terms

Intrinsic Factor: A glycoprotein secreted by parietal cells that is necessary for the absorption of vitamin B12 in the small intestine.

Hydrochloric Acid (HCl): A strong acid produced by parietal cells that helps break down food, activate digestive enzymes, and create an acidic environment in the stomach.

Gastric Pits: Microscopic depressions in the stomach lining where parietal cells and chief cells are located, responsible for secreting gastric juices.