A person had roti and dal for his lunch. Trace the changes in these during the passage via alimentary canal.
Please find below the solution to the asked query
The roti and dal are rich sources of carbohydrate and protein respectively. The digestion of carbohydrates and proteins takes place in the following way:
1. Digestion of carbohydrates:
Digestion of carbohydrates occurs in mouth and small intestines.
Digestion in Mouth
It begins in mouth. Mouth contains salivary glands that secrete saliva that contains enzymes like salivary amylase, lysozyme and electrolytes. Salivary amylase basically helps in carbohydrate (starch) digestion up to 30%. It converts starch into maltose.
Digestion in Small intestines:
The digestion of food takes place in duodenum, which is the first part of small intestine. The small intestine receives digestive juices from liver (bile juice) and pancreas (pancreatic juice). Small intestine itself also secretes digestive juices. Three of the major enzymes present in the pancreatic juice are − trypsin, amylase and lipase.
The amylase converts remaining starch into disaccharides.
After being partially digested, the food moves to the second part of small intestine where it is acted upon by enzymes such as maltase, sucrase, and lactase. These enzymes convert maltose/lactose and sucrose into glucose/galactose and fructose.
The digestion of proteins begins in the stomach and is completed in the small intestine
Digestion in stomach
digestive juice secreted in the gastric glands present on the stomach walls is called gastric juice. The food that enters the stomach becomes acidic on mixing with this gastric juice.
The main components of gastric juice are hydrochloric acid, pepsinogen, mucus, and rennin. Hydrochloric acid dissolves the bits of food and creates an acidic medium so that pepsinogen is converted into pepsin. Pepsin is a protein- digesting enzyme. It is secreted in its inactive form called pepsinogen, which then gets activated by hydrochloric acid. The activated pepsin then converts proteins into proteases and peptides.
Rennin is a proteolytic enzyme,released in an inactive form called prorennin. Rennin plays an important role in the digestion of milk in children.
Digestion in small intestines
The proteins, proteoses and peptides (partially hydrolysed proteins) on reaching the small intestines are acted upon by the proteolytic enzymes of pancreatic juice.
The enzymes of the intestinal juice like dipeptidases now act upon the dipeptides and converts them into absorbable form i.e amino acids.
Hope this information will clear your doubts about the topic.
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