Chyme in Human Digestion

Digestion is the process by which food that we eat is digested. The food is acted upon by various enzymes in the digestive system and this helps to break down the food into smaller subunits. These subunits have carbohydrates, fats, starch and proteins and thus they help in providing energy. For 4-5 hours the food is stored in the stomach and after that, it gets mixed with acidic acids of the stomach. The mixing takes place with the help of churning movements of the muscular walls of the stomach and then this food mixed with gastric juices is called chyme. This forms the basic chyme definition and chyme meaning. Chyme in the stomach is known as stomach chyme. To understand more about whats chyme we need to learn about the process of digestion. 

Digestion of Food

The digestion of food is accomplished by chemical and mechanical processes. The actual fragmentation of large pieces of food into smaller pieces that digestive enzymes can enter is referred to as mechanical digestion. Enzymes in chemical digestion break down food into small molecules that the body can access.

Digestion in Mouth

Chyme meaning can be understood from the process where the digestion in the human body starts. Mastication of food and facilitation of swallowing is performed by the buccal cavity. The teeth along with tongue and saliva also help in the mixing of food. Mucus helps in lubricating and adhering the masticated food particles into a bolus. The bolus is just a mass of food. The saliva is secreted by salivary glands into the oral cavity and it contains electrolytes like calcium, sodium and potassium ions and enzymes. The enzymes are salivary amylase and lysozyme. Ptyalin is another name for salivary amylase. This enzyme is absent from the saliva of many mammals like cows and buffaloes and carnivores animals like lions and tigers. 

Pigs have amylase in their saliva. The oral cavity initiates the process of digestion. It is done by hydrolytic action of the carbohydrate splitting enzyme, the salivary amylase. This enzyme hydrolyses about 30 percent of starch into a disaccharide-maltose. The lysozyme present in the saliva acts as an antibacterial agent that prevents infections. This mass of food(bolus) is then pushed down through the pharynx into the oesophagus. This process is called swallowing or deglutition. Through successive waves of muscular contractions, the bolus is moved down the oesophagus. These muscular contractions are called peristalsis. There is a sphincter between the oesophagus and stomach called the gastro-oesophagal sphincter. It controls the passage of food into the stomach.

Gastric Glands

The gastric glands play an important role in the formation of chyme food. The mucosa of the stomach has gastric glands. They have three major types of cells namely

• Mucous neck cells secrete mucus. 

• Peptic or chief cells that secrete pepsinogen.

• Parietal or oxyntic cells that secrete HCl and intrinsic factors. 

Digestion in the Stomach

We have a rough idea about chyme from the chyme definition part above. Chyme is formed in the stomach. Stomach stores the food for 5-6 hours. The thorough mixing of food with the gastric enzymes is called the chyme. This is the exact chyme medical definition and chyme definition anatomy. The pepsinogen is activated by hydrochloric acid and then it gets converted into active enzyme pepsin, the proteolytic enzyme of the stomach. Pepsin converts proteins into proteases and peptones. The mucus helps in protecting the stomach wall from concentrated hydrochloric acid. HCl provides the optimal pH for pepsins. Non-secretion of HCl or gastrectomy can lead to iron deficiency anaemia. Therefore, the mixing of the gastric juices along with food particles forms chyme. 

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                                        Figure: Chyme formation.

Digestion in the Small Intestine

The pancreatic juice contains enzymes. These are present in an inactive form and are activated later. trypsinogen, chymotrypsinogen, amylases, procarboxypeptidase, lipases and nucleases. Trypsinogen is activated by an enzyme that is enterokinase. This is secreted by the intestinal mucosa. The bile released into the duodenum consists of bile pigments. Bilirubin and biliverdin are bile pigments. Bile salts are sodium bicarbonate, sodium glycolate, sodium taurocholate. The bile also has cholesterol and phospholipids. Bile has no enzyme and it helps in the emulsification of fats. Emulsification means that they help in the breakdown of fats into very small micelles. Micelle is a combination of fatty acids, monoacylglycerols and bile salts. Bile also helps in activating the lipases. Goblet cells secrete mucus and are secreted by mucosal epithelium. The intestinal juice contains a variety of enzymes like disaccharides, maltase, dipeptidases, lipases, nucleosidases, etc. The mucus along with the bicarbonates from the pancreas protects the intestinal mucosa from acid as well as provide an alkaline medium for efficient enzymatic actions. Submucosal glands like Brunner’s glands also help in this process. 

Conclusion

We can conclude that chyme means the mixing of gastric juices with the food. This process takes place in the stomach. Further, this chyme is transferred to the small intestines for further digestion to take place. The process of digestion in the human body helps in breaking down food into smaller particles and then extract energy from it.