Gastric juice is a digestive fluid secreted by the gastric glands in the stomach. It plays a crucial role in the digestion and breakdown of food. The average human being secretes around 1.5 to 3 liters of gastric juice per day. Let's delve into the details of how this secretion occurs.

Composition of Gastric Juice:
Gastric juice is a complex mixture of various substances, including:

1. Hydrochloric Acid (HCl): This is the main component of gastric juice and helps in the breakdown of food and the activation of digestive enzymes.
2. Pepsinogen: This precursor enzyme is converted into pepsin by the acidic environment of the stomach. Pepsin helps in the digestion of proteins.
3. Mucus: It provides a protective layer to the stomach lining, preventing damage from the acidic environment.
4. Intrinsic Factor: It is necessary for the absorption of vitamin B12 in the small intestine.

Regulation of Gastric Juice Secretion:
The secretion of gastric juice is regulated by various factors, including:

1. Neural Regulation: The parasympathetic nervous system stimulates gastric juice secretion through the release of acetylcholine.
2. Hormonal Regulation: The hormone gastrin, released by the stomach's G cells, stimulates the release of gastric juice.
3. Presence of Food: The presence of food in the stomach triggers the release of gastric juice to aid in digestion.

Volume of Gastric Juice Secretion:
The volume of gastric juice secreted per day varies depending on factors such as diet, physical activity, and overall health. On average, an adult human secretes approximately 1.5 to 3 liters of gastric juice per day. However, this volume can increase during a meal due to increased stimulation of gastric glands.

Stomach Acid and pH:
The hydrochloric acid in gastric juice plays a vital role in digestion. It creates an acidic environment in the stomach with a pH ranging from 1.5 to 3.5. This low pH helps in the breakdown of proteins, activates pepsinogen into pepsin, and provides protection against harmful bacteria and pathogens.

Conclusion:
Gastric juice secretion is an essential process for the digestion of food in the stomach. It is a complex mixture of various substances, primarily hydrochloric acid, pepsinogen, mucus, and intrinsic factor. The volume of gastric juice secreted per day ranges from 1.5 to 3 liters, with variations depending on individual factors. The regulation of gastric juice secretion involves neural and hormonal factors, as well as the presence of food in the stomach. The acidic nature of gastric juice aids in the breakdown of food and provides protection against pathogens.

¶¶1.5 litres = 1500 ml....