CHAPTER 5 ( DIGESTIVE SYSTEM )

   Like other living oraganism, human need food to stay alive and to do activities. Human eats almost all kinds of food. However, there are some poeple who only consume vegetables, called vegetarian. Are the food cunsumed by the vegetarian enought to fulfil their bodies need of nutrition? Then, wahan food should we consume to keep our body health and balence?

   Food is the basic need to maintain human life. Do you know how much food you eat in a year? A scintist did a research on the amount of foods consumed by a certain female. Apparently, in a year, she has eaten up to 700 kgs of food. Yet, although she ete so much , her body weight didi not show any changes sinces the research was done. How does the body perform such amazing process?

A.Nutrients substance needed by the body

   Do you know why our body needs food everyday?

   Food is the vital need for living organism, especially human. The main roles of food for human are for growth and development. To repair and replace the damage cells, as the source of energy, to mintain the body temperature, and to maintain the balance of body metabolism.

   Good food is not those that can make us full, but the foood that can fulfil all the nutrition needed by our body. Eating the right food will help us to grow optimal,healthy,and not easily get sick. Food contains nutrients or substances with various function, for example carbohydrate, protein, fat, vitamin, and mineral.

1.Protein

   Protein is composed by smaller units called amino acids. Abous 20 types of amino acids are needed by the body, eight of them cannot be made by the body and called as essential amino acids. Essential amino acis canbe gained from the food. Meanwhile, the non-essential amino acids are amino acids that can be synthesized by the body.

   There are two types of protein in the food, i.e. animal protein derived from animal and vegetable protein derived from plant. Some example of animal protein are meat, milk, and egg. Some examples of vegetable protein are nuts and vegetables.

	Protein have many function in the body, such as the following.

- Built the body and repair the damaged cells

- From enzymes, hormones, and antibodies in the body

- From collagen compounds and albumin in the body

- From actin and myosin for muscle contraction

- As the source of energy for the body activities

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