Digestion of Protein Starts in the Stomach

Food entering the stomach stimulates

the release of gastrin a hormone which stimulates the secretion of digestive juices from cells in the lining of the

stomach wall.

Pepsinogen

Diagrammatic representation of a stomach.

Pyloric Sphincter

Gastric juiceOesophagus

HCl

Pepsinogen

Proteins Polypeptide

Pepsin

Parietal cells

Pepsinogen

Chief cells

Hydrochloric Acid

• Peptic cells secrete pepsinogen

Pepsinogen Pepsin

Pepsin ProteinPolypeptide

converts in to

In the presence of stomach acid is converted to

 T

 C

Pancreas Pancreatic duct T

Ts

 E

Small Intestine

C

 Cs

 P

 Pp

T

E

Ts

C

Cs

Trypsinogen

Enterokinase

Trypsin

ChymotrypsinogenChymotrypsin

P Protein Pp Polypeptides Simpkins & Williams, 1987

 P

• The enzyme peptidase is released from the small intestine wall.

Peptidase

Protein

Amino Acids

Converts

in to

Glucose

Amino Acid

Dipeptide

Tripeptide

Fructose

Bile Salts

Facilitated Transport

Active Transport

Blood C

apillary

Simple Diffusion

Lacteal

Absorption of Amino Acids in the Small IntestineS-cool. 2005.

References

• Simpkins & Williams, 1998 Advanced Human Biology. Italy: Collins Educational.

• http://www.s-cool.co.uk/topic_quicklearn.asp?loc=ql&topic_id=14&quicklearn_id=2&subject_id=3&ebt=&eb, 19.04.05.