Human digestive systemClass XI

Process of DigestionThe Process of

Digestion is accomplished by mechanical and

Chemical process in different parts of the

alimentary canal.

Alimentary canal consists of –1. Buccal Cavity2. Oesophagus3. Stomach4. Small Intestine5.Large Intestine

Digestion in the Buccal Cavity30% of the Starch is

hydrolyzed by salivary amylase/Ptyalin at a

pH of 6.8 into maltose.

Pharynx & Oesophagus1.No digestion take place in Pharynx &

Oesophagus.2. Act as a Cannel through which the

food passes into the stomach.

Digestion in the StomachThe gastric juice is a mixture

of mucus, hydrochloric acid and protein digesting

enzymes. (Pepsinogen and Pro-renin)

Protien Proteoses and Peptones

Digestion in the Small Intestine1.Duodenum receives biles,

pancreatic juice and the intestinal juice.

2.Bile salts helps in the immlusification of fats and

activate lipases.3.Pancreatic juice contains –

Trypsinogens, Chymotrysinogen Procarboxypeptides, Amylase Lipase and Nucleases.

Protein Trypsin Shorter polypeptidesPeptonesProteoses Chymotrysin

Shorter carboxypeptidases dipeptidespolypeptides aminopeptidases

Dipeptides dipeptidases Aminoacids

Lipids Lipases Diglycerides +(Triglycerides) Fattyacids

Diglycerids Lipases Monoglycerides + Fattyacids

Monoglycerides Lipases Fattyacids + Glycerol

QUESTION’S FOR SLOW LEARNER

1. What do you mean by digestion?

2.Name the enzyme present in human saliva. What is it’s pH?

3.In which part of alimentary canal, no digestion takes place?

QUESTION’S FOR AVERAGE LEARNER

1.What is the role of liver, gall bladder and pancreas in the digestion process ?2. Why acidic environment in the stomach is needed for food digestion?3. Which emzyme is requierd to digest milk proteins in the stomach of infants ?

QUESTION’S FOR BRIGHT LEARNER

1. In human, starch digestion starts in Buccal cavity but stops in the stomach. Why?2. Why are villi present in ileum and not in the stomach ?