A person had roti and dal for his lunch. Trace the changes in those during its passage through the alimentary canal.

Explanation

(1) Digestion of roti (carbohydrates) :
(a) Digestion of carbohydrates in oral cavity : In mouth chapati mixes with saliva. In saliva salivary Amylaze (ptylin) enzyme is present which converts starch of chapati into Maltose, Isomaltose and small dextrin (`alpha`-dextrin). 30% starch is hydrolysed in mouth.
Starch `underset"pH 6-8"overset"Salivary amylase"to` Maltose + isomaltose + `alpha`-dextrin.
(b) Digestion of carbohydrates in small intestine: From mouth to oesophagus and from there to stomach the path of half digested chapati is regulated by peristalsis (waves of alternate muscular contraction of oesphagus).
The food is stored in stomach for 4-5 hours. There is no enzyme present in gastrine causing digestion of carbohydrates. This half digested food is now known as chyme. Following process is seen in intestine.
(i) Process of pancreatic juice : The carbohydrate of chyme is hydrolysed into disachharide by pancreatic amylase.
Polysachharide (starch) `overset"amylaze"to` Disachharide .
(ii) The process of intestinal juice or succus entericus : Succus entericus possesses maltase, iso maltase, sucrase (invertase), lactase and a dextrin. These enzymes work on food and convert them into simple compounds like glucose, fructose or galactose.
Maltose `overset"Maltase"to` Glucose +Glucose
Isomaltose `overset"Isomaltase"to` Glucose + Glucose
Sucrose `overset"Sucrase"to` Glucose + Fructose
Lactose `overset"Lactase"to` Glucose + Galactose
`alpha`-dextrin `overset(alpha- "Dextrinase")to` Glucose .
(2) Digestion of protein : Proteins are made of amino acids, during its digestion protein decomposes and gets converted into amino acid.
There is no enzyme present for digestion of protein in saliva so protein is digested in stomach.
(a) Digestion of protein in stomach: Stomach generally stores food for 4-5 hours gastrin gland secretes gastric juice. It possesses HCI, inactive enzymes, pepsinogen and renin.
Following processes are done in stomach :
Pepsinogen (inactive) `overset"dil HCl"to` Pepsin
Protein `overset"Pepsin"to` Peptones + Proteoses
Prorenin (inactive) `overset"HCl"to` Renin (active)
(b) Digestion of protein in small intestine :
(i) Process of panereatic juice : Trypsinogen, chymotrypsinogen and procarboxy peptidase are associated with digestion of protein.
Trypsinogen `overset"Enterokinase"to` Trypsin
Proteins `overset"Trypsin"to` Dipeptide
Chymotrypsinogen `overset"Trypsin"to` Chymotrypsin
Peptones `overset"Chymotrypsin"to` Dipeptides
Procarboxypeptidase `overset"Trypsin"to` Carboxypeptidase
Proteoses `overset"Carboxypeptidase"to` Dipeptides
(ii) The action of intestinal juice succus entericus (intestinal juice) possesses enzyme enterokinase, amino peptise and dipeptise. It shows following processes
Peptides `overset"Amino peptidase"to` Amino acid
Dipeptides `overset"Dipeptidase"to` Amino acid
Megamolecules are converted into simple components. That is an end product of chapati and Dal which are absorbed by villies of intestine. Undigested food is removed as faeces.