Difference Between Physical and Chemical Digestion

Physical vs Chemical Digestion

The process of breaking down foods in the elementary track to gain nutrients in the food is known as digestion. The obtained nutrients in this process are then absorbed into the circulatory system and circulated all over the body with the blood. These nutrients are essential for providing energy or for synthesis of specific substances that the body needs. Digestion is basically taken place by physical and chemical means. Both types of digestion are important to increase the rate of digestion and to provide a proper nutrient absorption. Normally the foodstuffs are bulky and difficult to extract nutrients directly from them. Therefore, it is necessary to chop the food down first using physical processes and then hydrolyze the nutrients enzymatically to smaller molecules using chemical processes.

Physical Digestion

Physical digestion is the breaking down of food particles into smaller particles by physical processes such as chewing, smashing etc. It is mainly achieved by teeth, stomach contractions and bile. Physical digestion increases the surface area for enzymatic reactions, hence increases the rate of chemical reaction indirectly.

Chemical Digestion

The process of transforming food into smaller particles through the enzymatic reactions is referred to as chemical digestion. Enzymes are used to catalysis the reactions by splitting chemical bonds in the process of hydrolysis. There are three types of digestive enzymes, namely; carbohydrates, lipases, and proteases, which hydrolysis carbohydrates, fats, and proteins respectively. These enzymes are found in saliva, gastric juice, pancreatic juice, and intestinal juice, secreted by the salivary glands, gastric glands, pancreases, and wall of the small intestine respectively. Secretion of digestive enzymes is initiated by expectation, reflex stimulation, hormones or direct mechanical stimulation.

What is the difference between Physical Digestion and Chemical Digestion?

• Physical digestion involves physical changes while chemical digestion involves chemical changes in food.

• Physical digestion helps to break down large food particles into smaller particles, whereas chemical digestion breaks large particles into small molecules.

• Chemical digestion involves enzymes and enzymatic actions, whereas physical digestion involves physical actions including chewing, mashing and breaking food.

• Physical digestion increases available surface area for chemical digestion and increase rate of enzymatic reactions, whereas chemical digestion allows absorbing smaller food molecules into the blood stream.

• Teeth, gut muscles and the action of solutions like bile help to achieve physical digestion while chemical digestion is achieved by digestive enzymes.