$A$ person had roti and dal for his lunch. Trace the changes in those during its passage through the alimentary canal. What are the various enzymatic types of glandular secretions in our gut helping digestion of food? What is the nature of end products obtained after complete digestion of food?

(N/A) $(1)$ Digestion of roti (carbohydrates):
$(a)$ Digestion of carbohydrates in oral cavity: In the mouth, chapati mixes with saliva. Saliva contains the enzyme salivary amylase (ptyalin), which converts the starch of the chapati into maltose, isomaltose, and small dextrins ($\alpha$-dextrin). About $30\%$ of starch is hydrolyzed in the mouth.
$\text{Starch} \xrightarrow[pH 6.8]{\text{Salivary amylase}} \text{Maltose} + \text{Isomaltose} + \alpha\text{-dextrin}$
$(b)$ Digestion of carbohydrates in the small intestine: The food moves through the esophagus to the stomach via peristalsis. The food is stored in the stomach for $4-5$ hours. There are no carbohydrate-digesting enzymes in gastric juice. This partially digested food is called chyme.
$(i)$ Pancreatic juice: Pancreatic amylase hydrolyzes the carbohydrates in chyme into disaccharides.
$\text{Polysaccharide (starch)} \xrightarrow{\text{Amylase}} \text{Disaccharides}$
$(ii)$ Intestinal juice (succus entericus): Succus entericus contains maltase, isomaltase, sucrase (invertase), lactase, and $\alpha$-dextrinase. These enzymes convert disaccharides into simple sugars like glucose, fructose, or galactose.
$\text{Maltose} \xrightarrow{\text{Maltase}} \text{Glucose} + \text{Glucose}$
$\text{Isomaltose} \xrightarrow{\text{Isomaltase}} \text{Glucose} + \text{Glucose}$
$\text{Sucrose} \xrightarrow{\text{Sucrase}} \text{Glucose} + \text{Fructose}$
$\text{Lactose} \xrightarrow{\text{Lactase}} \text{Glucose} + \text{Galactose}$
$\alpha\text{-dextrin} \xrightarrow{\alpha\text{-Dextrinase}} \text{Glucose}$
$(2)$ Digestion of protein (dal):
$(a)$ Digestion in the stomach: Gastric glands secrete gastric juice containing $HCl$ and inactive enzymes (pepsinogen and prorenin).
$\text{Pepsinogen} \xrightarrow{HCl} \text{Pepsin}$
$\text{Protein} \xrightarrow{\text{Pepsin}} \text{Peptones} + \text{Proteoses}$
$(b)$ Digestion in the small intestine:
$(i)$ Pancreatic juice: Trypsinogen is activated by enterokinase to trypsin, which then activates other enzymes.
$\text{Trypsinogen} \xrightarrow{\text{Enterokinase}} \text{Trypsin}$
$\text{Proteins} \xrightarrow{\text{Trypsin}} \text{Dipeptides}$
$(ii)$ Intestinal juice: Contains aminopeptidases and dipeptidases that break down peptides into amino acids.
$\text{Dipeptides} \xrightarrow{\text{Dipeptidase}} \text{Amino acids}$
Final end products are glucose, fructose, galactose (from carbohydrates) and amino acids (from proteins), which are absorbed by the intestinal villi.