March 4, 2014

10th Biology - Nutrition in Human Beings- New Syllabus

Nutrition in Human Beings: Human digestive system is very complex in nature where different parts are involved and perform different functions by using various digestive juices and enzymes.

Let us observe the figure of digestive system. The alimentary canal is basically
a long tube extending from the mouth to the anus we can see that this tube
has different parts. Various regions are specialized to perform different functions.
• What happens to the food once it enters our body?
• How it get digestive in the alimentary canal? let us discuss. We eat various types of food which has to pass through the same digestive tract. The process of taking food in the body is called ingestion. Naturally the food has to be processed to generate particles which are small enough to be picked up by our body. The texture
also needs to be such that it may be easily absorbed.

Steps in the passage of food through alimentary canal or gut. Food is masticated by our teeth in the mouth and mixed with saliva to make it wet and slippery it helps in smooth passage through our alimentary canal to the stomach. Saliva is secreted by three pairs salivary glands located at the side of the jaw and below the tongue. They contains an enzyme amylase (ptyalin) which helps in the breakdown of complex carbohydrates to simple ones). Such process of breaking down of complex food

substances into the simple substances so that they can be used by the body with the help of enzymes is called digestion. The tongue helps in mixing the food and pushing it into the next part. The lower jaw also helps in the whole process. To know the chemical nature of saliva, let us do the litmus paper activity.

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