Saturday, March 5, 2016

HUMAN DIGESTIVE SYSTEM- PART-1





Children we are going to learn about human digestive system and its function. Human digestive system starts from Mouth, buccal cavity, pharynx, oesophagus, stomach, small intestine, large intestine, rectum and anus are the parts in the human digestive system.
Mouth, salivary glands and their functions Mouth is only an opening of the digestive system. Taking in of food digestive system. Taking in of food through mouth is called ingestion. The cavity or space in the mouth is called oral cavity or buccal cavity.
Digestion starts in buccal cavity. Teeth, tongue and openings of three pairs of salivary gland are present in baccual cavity.
Physical and chemical nature of the food changes when it is masticated with the help of teeth and mixed with saliva.
There are four types of teeth in man- incisors, canines, premolars and molars- each for a specific functions.
The arrangement of teeth is same on the upper and lower jaws.An adult human has thirty two teeth – 8 incisors, 4 canines, 8 premolars, and 12 molars.
Tongue is muscular and pushes the food on to the teeth during mastication. Taste buds on the tonge sense the taste of food.
Three pairs of salivary glands are present in the buccal cavity. They are parotid, sub-lingual and sub-maxillary glands .
Parotid glands are present near the ear. Secretion from these glands is sent into buccal cavity through ducts.
Other two pairs of glands open below the tongue through ducts. Saliva is released when food is present in buccal cavity. It is also released at the sight, smell and even thought of food. Saliva contains large amount of waste small amounts of salts and mucous.
Saliva is slightly alkaline in nature. It contains an enzymes called salivary. Amylase converts starch into dextrin and maltose sugar. As the food stays only for short time in the buccal cavity, starch is partly digested here.
Mucous present in the saliva makes the food sticky and helps its passage easy through pharynx. The food in buccal cavity undergoes mainly physical changes. Saliva is also useful as a solvent for dissolving the chemical substance present in food.

THANKYOU,
NANDITHA AKUNURI

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