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Dear student
8.
| Alimentary canal | Digestive system |
| The alimentary canal refers to the passage way for the food that we eat. It starts from the mouth and ends at the anus. It includes the organs like mouth, esophagus, stomach, small intestines, large intestines, rectum and anus | Digestive system refers to the system of organs that help in the digestion of food. Digestive system consists of the alimentary canal and the associated digestive glands like salivary glands, gastric glands, pancreas and liver that help in digestion. |
9. Digestion of starchy carbohydrates begins in mouth. It then takes place in stomach & in small intestine. Enzymes which carry out digestion are known as carbohydrolases & amylolytic enzymes.
1. Digestion in mouth:-Slightly acidic saliva, secreted by salivary glands contains salivary amylase or ptyalin. Chewing helps in proper mixing of food with salivary amylase.
This enzyme helps in digestion of up to 30% of carbohydrates. Mucus in saliva lubricates and adheres food particles into Bolus & this bolus is then transferred to stomach.
Action of salivary amylase is inhibited slowly by acidic gastric juices in stomach, it takes around 20 min to completely inhibit the enzyme.
2. Digestion in stomach:- In stomach the gastric juices contain no carbohydrolases so no digestion of carbohydrates takes place in stomach.
3. Digestion in small intestine:- digestion of food chyme takes place in 1st part of small intestine- Duodenum. Here it is mixed with 3types of secretions- (i) Bile juice- its a secretion of liver (II)Pancreatic juice- It contains pancreatic amylase & secreted by hepatopancreatic duct & (III) Intestinal juices-it contain enzymes like maltase, lipase, sucrase
Pancreatic amylase hydrolyse the remaining starch into disaccharides. it acts only in alkaline mediu which is provided by bile juice.
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