Question

1.
In human alimentary canal, name the site of complete digestion of various components of food.
loin the procese of digestion​

Answer 1

Answer:-

In human alimentary canal, the site of complete digestion of various components of food is small intestine.

Explanation of process of digestion:-

• The digestion of food starts in mouth.
• The teeth help in breaking down the food in small particles.
• The enzyme salivary amylase present in saliva which is produced by salivary glands helps in the conversion of starch into sugar.
• Further, the food reaches the stomach.
• The gastric glands in the stomach produce three essential things responsible for proper digestion.
• It produces pepsin which helps in the digestion of proteins.
• It produces hydrochloric acid which helps in the proper functioning of pepsin by making the medium of food acidic.
• The gastric glands also produces mucus. It helps in protecting the the walls of the stomach from the action of hydrochloric acid.
• The food father passes into small intestine.
• In the initial part of small intestine which is called as duodenum, the food is mixed with bile juice produced by liver and pancreatic Juice produced by pancreas.
• The bile juice makes the acidic medium of the food alkaline which helps in the proper digestion of food with the help of pancreatic juice. This also doesn't allow the acidic medium of the food to destroy the walls of small intestine.
• The pancreatic juice contains lipase and trypsin. The lipase breaks down fats and trypsin breaks down proteins.
• Further in the small intestine, the food is digested with the help of intestinal juice.
• The intestinal juice converts carbohydrates into glucose, fats into fatty acids and glycerol, and proteins into amino acids.
• The walls of small intestine have several finger like projections which are usually called as villi.
• These villi helps in the process of absorption and assimilation.
• It is connected with blood vessels and it also increases the surface area for the absorption of digested food.
• The digested food is absorbed here and the blood helps in transporting the absorbed food to all the cells in the body.
• Then, the undigested food passes into the large intestine where the water is absorbed and waste material is further removed through anus.

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Answer 2

Answer:

The complete digestion takes place in small intestine.

Explanation:

Mechanism of Digestion of Food

• Food digestion process begins in the mouth. Food is complex in nature.
• To breakdown food and absorb it, we need biological catalyst known as enzymes.
• Mouth contains salivary glands that secrete saliva. Saliva contains an important enzyme known as salivary amylase that breaks down starch into simple sugars.
• The food is mixed thoroughly with saliva and moved around the mouth while chewing by the muscular tongue.
• The food then passes via esophagus into the stomach. The movement of the food inside the esophagus occurs via rhythmic contraction of muscles, this is known as peristalsis OR peristaltic movement.
• The stomach is a large organ which expands when food enters it. The muscular walls of the stomach help in mixing the food thoroughly with more digestive juices.
• Stomach contains gastric glands that secrete mucus, hydrochloric acid and pepsin.  
• Pepsin is a protein digesting enzyme.  
• The hydrochloric acid creates an acidic medium which facilitates the action of the enzyme pepsin.  
• The mucus protects the inner lining of the stomach from the action of the acid under normal conditions
• The exit of food from the stomach is regulated by a sphincter muscle which releases it in small amounts into the small intestine.
• After stomach, food then enters into small intestine. This is the longest part of the alimentary canal which is fitted into a compact space because of extensive coiling.
• Small intestine is larger in herbivores due to cellulose digestion compared to carnivores. Herbivores eating grass need a longer small intestine to allow the cellulose to be digested. Meat is easier to digest, hence carnivores like tigers have a shorter small intestine
• Complete digestion of carbohydrates, proteins and fats occurs in small intestine.
• Small intestine receives secretions from pancreas and bile from the liver. The food coming from the stomach is acidic and has to be made alkaline for the pancreatic enzymes to act.
• Bile helps in emulsification of fats.  
• Pancreas secrete enzymes such as trypsin for protein digestion and lipase for breaking down emulsified fats.  
• Intestinal wall also contains glands that secrete intestinal juice. The enzymes present in it finally convert the proteins to amino acids, complex carbohydrates into glucose and fats into fatty acids and glycerol
• Small intestine has villi that increases the surface area for the absorption of food. The villi are richly supplied with blood vessels which take the absorbed food to each and every cell of the body, where it is utilized for obtaining energy, building up new tissues and the repair of old tissues.
• The un absorbed food is then transferred to large intestine where water is absorbed.
• Undigested food is then expelled out from the anus. The exit of this waste material is regulated by the anal sphincter.