Understanding gastrointestinal secretions

The gastrointestinal tract is something that acts as a bridge between the mouth to the anus. It is the pathway for the digestive tract. The gastrointestinal secretions are secreted by the GI tract, especially by the gastric epithelium. The gastric epithelium is made up of two types of glands: the oxyntic gland and the pyloric gland. Oxyntic glands also called parietal cells are found in the fundus. It covers 80% of the stomach. Pyloric glands are called G cells and they are found in the antrum. It covers over 20% of the stomach. The secretions from the digestive system play a key role in formulating food intake. It aids in adsorption, assimilation, digestion, metabolism and excretion. Learn more about the gastrointestinal tract, cells involved in the gastrointestinal secretions, does caffeine increase gastrointestinal secretions, gastrointestinal secretions and their functions.

Cells of the gastrointestinal secretions:

The cells commonly associated with the production of gastrointestinal secretions that facilitates digestion are as follows:

• Chief cells: They are also called peptic or zymogenic cells found in the gastric glands. It secretes pepsinogen, chymosin gastric lipase and leptin.
• D cells: They can also be referred to as delta cells that are present widely in the pancreas, stomach and intestine. It is used in the secretion of  somatostatin 
• Enterochromaffin-like cells: These can be called ECL cells are a specific type of neuroendocrine cells that are found in the gastric epithelium and have the ability to secrete histamine.
• Enterochromaffin cells: These are the most familiar and highly existing forms of neuroendocrine cells present in the gastrointestinal tract including the appendix, colon and small intestine. It is involved in the production of ghrelin, serotonin, obestatin and atrial natriuretic peptide. 
• G cells: These cells are the mostly found type of neuroendocrine cells. It is found in the pyloric antrum and is also found in the pancreas and duodenum. It is involved in the secretion of gastrin.
• Mucous cells: They are the cells that entirely cover the walls of the digestive tract. They are found in the mucous membrane. It is involved in the production of mucus and bicarbonate.
• Parietal cells: These are also called oxyntic cells that are found on the epithelial cells of the stomach. They are involved in the secretion of acid, intrinsic factors and leptin.

Does caffeine increase gastrointestinal secretion?

The answer to the question does caffeine increase gastrointestinal secretions is no. Coffee is frequently claimed as a source or factor that triggers dyspeptic symptoms. But the actual fact discovered by a recent study states that there is no link connecting coffee and dyspepsia. Heartburn and heart congestion is the most widely mentioned symptom following the consumption of coffee. 

Coffee has been shown to induce and promote gastro-oesophageal reflux. Coffee increases gastrin production and stomach acid output. But, the studies and investigations associated with the influence on lower oesophagal sphincter pressure produce inconsistent and varying results. Coffee is also found to increase the adaptive flexibility and relaxation of the proximate stomach. It is also found to impede or slow down gastric emptying. 

Other studies on this show that coffee has no effect on stomach evacuation or small intestinal transit. Coffee has zero calories, and its impacts on the intestinal system cannot be attributed or directly linked to volume load, acidity and osmolality. Therefore, it must have therapeutic or pharmacological action. Caffeine cannot be blamed primarily for these gastrointestinal secretions and related issues. Coffee causes gastro-oesophageal reflux but has little effect on gastrointestinal secretions. 

Gastrointestinal secretions and their functions

The most common gastrointestinal secretions and their functions are listed below. They are:

• Gastric acid: It is required for protein metabolism,  absorption and assimilation of Ca+, vitamin B12, iron and thyroxine. It has been postulated that stomach acid decreases or reduces food allergy and sensitivity. Gastric acid can also help to avoid microbial contamination, bacterial growth and enteric illnesses.
• Pepsinogen: It is involved in the breakdown of food during digestion by metabolising the protein. It is the most abundant protein-digesting enzyme.
• Leptin: It is used to maintain energy balance in the body. It is helpful in monitoring the rate or level of food intake and energy consumption.
• Serotonin: It plays a key role in regulating appetite. It is associated with the secretion of acids during digestion.
• Histamine: It facilitates the secretion of gastric juice. It is also involved in providing protection from external pathogens.
• Gastrin: It plays a key role in the production of Hydrochloric acid. It is involved in gastric motility like muscular contractions. 
• Mucus: It is used in the lubrication of food and it also forms a protective layer over the stomach and epithelium.
• Obestatin: It mitigates or reduces gastrointestinal motility. It protects the system from inflammation.

Conclusion

Gastrointestinal secretions play a vital role in digestion. The efficiency of gastrointestinal secretions is found to diminish with age. Various researches are being performed in recent times about gastrointestinal secretions, diseases associated with the gastrointestinal secretions, various strategies to stimulate or suppress the secretion and treatment or cure for the diseases associated with it. Further development and study of gastrointestinal secretions can provide a wide range of information about digestion and associated functions.