Question

Mention the role of the different parts of alimentary canal

Answer 1

Alimentary canal, also called digestive tract, pathway by which food enters the body and solid wastes are expelled. The alimentary canal includes the mouth, pharynx, esophagus, stomach, small intestine, large intestine, and anus.

Oral Cavity
The upper portion of alimentary canal is mouth. It is bounded by lips and contains cheeks, gums, teeth, tongue and muscles. The teeth in the mouth chew and masticate the food. It increases the surface area of the food so that various enzymes can act on it more effectively.

Tongue it is a muscular sensory organ, with taste buds on it. It helps in tasting the food and also helps in the movement in the cavity. In adult man 32 teeth are found which perform different functions. Formation of teeth takes place twice in man. The first set, called the milk teeth, starts appearing at the age of 6 months. This continues up to 2-3 years. Cutting, biting and chewing of food are the main functions of teeth.

The oral cavity passes into a pharynx. The masticated and partially digested food then goes down into the stomach through a tube called oesophagus.

Oesophagus:
It is a muscular, tubular part of the alimentary canal. It is about ten inches long. It corresponds to the neck region of man. It represents the narrowest portion of the alimentary canal. By peristalsis (a type of muscle movement) the food passes down the oesophagus.

Stomach:
It is located below the diaphragm and appears as a sac-like structure. It serves as the storehouse of food where partial digestion takes place. The wall of the stomach is muscular and contains many small gastric ducts. About 40 million gastric glands are found in the wall of the stomach.

Small intestine:
The small intestine is about 6 metres in length and 2.5 centimetres in thickness. There are three divisions of the small intestine: duodemum, jejunum and tleum. Duodenum is the first part which begins from the pyloric stomach, and is C-shaped. In the middle of the duodenum two different ducts open through a common aperture. One of the ducts is the common bile duct and the other is the pancreatic duct. Bile juice is poured into the duodenum through the common bile duct.

Large intestine:
The ileum passes behind into the egressive (outgoing) zone of the digestive tract commonly called the large intestine, which in man is about 1.5 m in length. The large intestine can be divided into two parts: anterior, colon and posterior, rectum. At the junction of iloeum and colon, there is a blind (one end closed) out pushing called caecum. The free end of this caecum forms a process which is termed the vermiform appendix (vermes=worm, vermiform = worm-shaped). In man, the vermiform appendix has outlived its usefulness i.e., it is a vestigial organ.

Answer 2

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Write different parts of alimentary canal are :

• Bucal  Cavity - Mouth, also called oral cavity or buccal cavity, in human anatomy, orifice through which food and air enter the body.
• The mouth opens to the outside at the lips and empties into the throat at the rear; its boundaries are defined by the lips, cheeks, hard and soft palates, and glottis.
• Foodpipe or oesophagus - The food pipe (oesophagus) is part of your digestive system. It is the tube that carries food from your mouth to your stomach. It lies behind the windpipe (trachea) and in front of the spine.
• Stomach - the organ in your body where food goes after you have eaten it
• Small intestine - the part of the intestine that runs between the stomach and the large intestine; the duodenum, jejunum, and ileum collectively.
• Large intestine - The long, tube-like organ that is connected to the small intestine at one end and the anus at the other. The large intestine has four parts: cecum, colon, rectum, and anal canal. Partly digested food moves through the cecum into the colon, where water and some nutrients and electrolytes are removed.
• Rectum and Anus - The rectum is a chamber that begins at the end of the large intestine, immediately following the sigmoid colon, and ends at the anus (see also Overview of the Anus and Rectum).

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