Question

HCL is secreted by which of the following cells of the stomach?
(a) Chief cells
(b) Parietal cells (oxyntic cells)
(c) Peptic cells
(d) Goblet cells

Answer 1

Hint: The cells secreting HCL in the stomach are epithelial cells that are located in the gastric glands found in the lining of the fundus and the cardiac part of the stomach.

Complete answer:
Parietal cells or oxyntic or delomorphous cells are the epithelial cells. They secrete hydrochloric acid (HCl) and intrinsic factor. They contain an in- depth secretory network called canaliculi from which the HCl is secreted to transport into the stomach. The enzyme hydrogen- potassium ATPase is exclusive to the parietal cells and is involved in the transportation of the hydrogen ions.
- HCL production starts with a combination of water and carbon dioxide within the parietal cell cytoplasm to produce carbonic acid, catalyzed by carbonic anhydrase. Carbonic acid then spontaneously dissociates into a hydrogen ion and a bicarbonate ion.
- The hydrogen ion that was formed is transported into the stomach lumen via the hydrogen- potassium ATPase. This channel uses ATP energy to exchange potassium ions within the stomach with hydrogen ions within the parietal cell.
- The bicarbonate ion is transported out from the cell into the blood with the help of a transporter protein called anion exchanger which transports the bicarbonate ion out of the cell in exchange for a chloride ion. This chloride ion is then transported into the lumen of the stomach via a chloride channel.
- This leads to both hydrogen and chloride ions being present within the stomach lumen. Their opposing charges lead to them associating with each other to form hydrochloric acid (HCl) .
So, the correct answer is,’ Parietal cells’.

Note:
1. Our stomach secretes a sticky, neutralizing mucus that clings to the stomach walls. This mucus protects the stomach from being digested or burnt by its enzymes, or hydrochloric acid. Damage in the mucus layer can result in painful and unpleasant stomach ulcers.
2. Chief cells are responsible for secreting pepsinogen into the lumen of the gastric gland.
3. Parietal cells also play an important role in the absorption of vitamin $B_{12}$.