Discuss through comparing and contrasting the processes of chemical and physical digestion

Target Language or Knowledge:

Physical and chemical digestive processes are both required in order for food to be digested efficiently. Both physical and chemical digestion occur at various stages in the overall process of digestion. For example, both types of digestion occur in the mouth, where the process of digestion begins. Physical digestion occurs in the mouth through the processes of biting and chewing. These processes are important because they allow for the initial larger pieces of food to be broken down into smaller pieces. This is important because it creates a greater surface area for the enzymes involved in chemical digestion to act on and makes the food small enough for swallowing. As this occurs, chemical digestion also begins in the mouth with the secretion of saliva. Saliva contains an enzyme called amylase, which is able to break starch molecules down into smaller glucose molecules. This is necessary because starch molecules are too large to be absorbed through the walls of the digestive system, but glucose molecules are smaller and can be absorbed through the gut wall. Bile and Stomach Acid aid chemical digestion via enzymes. These both help to support the physical digestion (churning in the stomach) that has occurred by continuing to increase the surface area of food particles. Increase in surface area allows for efficient absorption of food molecules to be taken in (assimilation) into the body.

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