Gastric glands present in the wall of the stomach do NOT release: 

The correct answer is saliva.

Key Points

• The gastric glands in the stomach are responsible for secreting various substances that aid in digestion.
• These glands release pepsinogen, which is converted to pepsin in the presence of hydrochloric acid.
• Hydrochloric acid (HCl) is secreted by the parietal cells in the gastric glands and helps in maintaining an acidic environment.
• Mucus is also secreted by the gastric glands to protect the stomach lining from the corrosive effects of HCl and digestive enzymes.
• Saliva is not secreted by the gastric glands; it is produced by the salivary glands located in the mouth.

Additional Information

• Pepsinogen: An inactive enzyme precursor secreted by the chief cells in the stomach, which is activated to pepsin by the acidic environment.
• Hydrochloric Acid (HCl): Produced by the parietal cells in the stomach, it creates an acidic environment, which is essential for the activation of pepsin and for killing pathogens.
• Mucus: Secreted by the mucous cells in the stomach lining, it forms a protective barrier to prevent the stomach lining from being digested by gastric juices.
• Saliva: A digestive fluid produced by the salivary glands in the mouth, containing enzymes like amylase that begin the process of digestion.
• Gastric Glands: Located in the lining of the stomach, these glands include mucous cells, parietal cells, and chief cells, each secreting different substances necessary for digestion.