Question

What is digestion?starting from the mouth. State the various steps involved in digestion.​

Answer 1

⠀⠀ıllıllı ᎪΝՏᏔᎬᎡ ıllıllı

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The process of breaking down for conversion of food into very fine and soluble particles is called digestion.

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Various various steps involved in digestion are:

Step 1:

Mouth ➠ Saliva ➠ Saliva helps to moisten and soften the food so that it can be easily swallowed.

Step 2:

Food Pipe ➠ Food Pipe is a muscular organ that helps in contribution of its muscles is responsible for pushing the food down into the stomach.

Step 3:

Stomach ➠ In stomach the food gets mixed with the gastric juice, secreted by the gastric glands of the stomach. Gastric juice helps in digestion of food.

Step 4:

Liver and Pancreas ➠ Liver secrete bile juice and pancreas secreted pancreatic juice which contains certain enzymes that help in the digestion of food.

Step 5:

Small Intestine ➠ The small intestine absorbs nutrients from the digested food and take them to all the cells of the body, through the blood capillaries.

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Answer 2

Answer:

Digestion is the process of breakdown of complex organic substances into simple inorganic ones with the help of enzymes.

Explanation: THE PROCESS OF DIGESTION

1. It first starts off at the mouth which is rather called 'The Munching Machine'. In the mouth the teeth help in chewing, shredding & cutting the food. While the teeth crush food saliva is secreted from the three salivary glands [ namely : Sublingual, Submaxillary & Parotid ].This saliva contains the enzyme - Salivary Amylase or Ptyalin. This enzyme digests the Starch/Carbohydrates. This process of chewing the food and mixing of it with the saliva is called Mastication. After mastication, a slurry mass of food called Bolus gets formed.
2. This Bolus then passes through the Oesophagus (or) Esophagus. This Oesophagus is a tube like structure which connects the buccal cavity (mouth) and the stomach. In the Oesophagus no digestion takes place but just food passes through it. At the opening of the stomach there is a sphincter muscle  which regulates the movement  of bolus into the stomach.

  3.  The Stomach is a bag like organ where digestion of food continues.                           Inside the stomach, stomach acid( HCl ) is secreted from stomach walls. The food is churned along with HCl. HCl makes the condition  the stomach into acidic which facilitates the action of the enzyme Pepsin which digests the proteins. After digestion at the stomach a smooth porridge like consistency called Chyme is formed. At the opening of the Duodenum(first part of the small intestine) the Pyloric sphincter muscle is present which regulates the movement of chyme into the duodenum.

  4.  Inside the small intestine, bile juice(from liver) which converts large fat molecules to small fat globules [This process is called emulsification], pancreatic juice ( which has enzymes - trypsin[digests protein], lipase[fats] & amylase[carbs] ) & intestinal juice are secreted.  The juice Succus entericus is secreted. The small intestine is coiled to increase surface area for absorption. It has thousands of finger-like projections called villi & smaller ones called microvilli which also help in increasing the surface area for absorption.

  5.  This digested food then passes through the large intestine. Here no digestion but absorption of water takes place( there are no villi and microvilli in the large intestine ). The undigested final product is called the faecal material. This material is stored in the last part of the large intestine - Rectum. And when time comes it is excreted out through the Anus.

This process of excreting out faeces through the anus is called defaecation.

The long tube extending from the mouth to the anus is called Alimentary canal