| Enzyme | Site of action | Substrate | |
| 1. | Nucleases | Intestine | Nucleic acids |
| 2. | Pepsin | Stomach | Dipeptides |
| 3. | Salivary amylase | Mouth | Starch |
| 4. | Sucrase | Intestine | Sucrose |
| I: | is the largest gland of the body |
| II: | is situated in the abdominal cavity, just below the diaphragm |
| III: | has two lobes that are its structural and functional units |
| 1. | alkaline bile secreted by the liver cells |
| 2. | an enzyme, enterokinase, secreted by the intestinal mucosa |
| 3. | an enzyme, enterokinase, secreted by the duodenal Brunner’s glands |
| 4. | a hormone, secretin, secreted by the intestinal mucosa |
| 1. | Serosa is the outermost layer and is made up of a thin mesothelium with some connective tissues. |
| 2. | Muscularis is formed by skeletal muscles usually arranged into an outer circular and an inner longitudinal layer. |
| 3. | The sub-mucosal layer is formed of loose connective tissues containing nerves, blood and lymph vessels. |
| 4. | The innermost layer lining the lumen of the alimentary canal is the mucosa. |
| 1. | Parietal cells of gastric mucosa |
| 2. | Goblet cells |
| 3. | Paneth cells in the small intestine |
| 4. | Brunner’s gland in the duodenum |