The pancreas is a compound (both exocrine and endocrine) elongated organ situated between the limbs of ' $U$ ' shaped duodenum.

Internal structure of pancreas consist of two parts, i.e., the exocrine and endocrine part.

(i) Exocrine part consists of rounded lobules called acini that are involved in the secretion of alkaline pancreatic juice of pH 8.4. The pancreatic juice is mainly involved in the digestion of starch, proteins, fats and nucleic acids.

(ii) Endocrine part is involved in the secretion of hormones like, insulin and glucagon that regulate glucose metabolism.

Small intestine is the principle organ for the absorption of nutrients. The process of digestion complete here only and the final products of digestion are absorbed through the mucosa into the blood stream.

The absorbed form of different food materials are

Food Material	Absorbed Form
Carbohydrate	Glucose
Protein	Amino acid
Fat	Fatty acid

Human digestive system consists of two main parts, alimentary canal and digestive glands.

Alimentary canal comprises of following parts

(i) Mouth (ii) Pharynx (iii) Oesophagus (iv) Stomach (v) Small intestine (vi) Large intestine (vii) Rectum (viii) Anus

Digestive glands include

(i) Salivary glands are situated just outside the buccal cavity and secrete salivary juice into it.

(ii) Liver is the largest gland in the body, situated in the abdominal cavity just below the diaphgram and has two lobes. It secreates bile which helps in the digestion of fats.

(iii) Pancreas is the compound organ situated between the limbs of U-shaped duodenum acting as endocrine and exocrine organ. The exocrine portion secretes pancreatic juice where endocrine portion secretes hormones like insulin and glucagon.

Gall Bladder is a pear-shaped sac-like structure, that is attached to the posterior surface of the liver by a connective tissue. The bile secreted by the hepatic cells of liver, passes through the hepatic ducts and gets stored and concentrated in the gall bladder. Non-functioning and removal of gall bladder would be bile to simply run in the continuous stream from the liver into the intestine. It would not be as concentrated as the bile started in gall bladder actually is. The body gradually adjust to it but a low fat diet is recommonded because fat digestion is significantly reduced after gall bladder removal.

(a) Absorption of amino acids and glycerol takes place in the small intestine.

(b) The faeces in the rectum initiate a neural reflex causing an urge for its removal.

(c) Skin and eyes turn yellow in liver infection.

(d) Rennin is a proteolytic enzyme found in infants gastric juice.

(e) Pancreatic juice and bile are released through hepato-pancreatic duct. (f) Dipeptides, disaccharides and glycerides are broken down into simple substances in the region of small intestine called duodenum.