What happens to salivary amylase when it arrives with the bolus in the stomach? Because of this, what happens to carbohydrate digestion? (Hint: Look up the optimum pH for amylase and what is the pH of the gastric juices)

Salivary amylase becomes inactive in stomach. Carbohydrate digestion halts until the bolus enters small intestine.

Explanation:

Salivary amylase is present in saliva and breaks down starch in food thus it helps in carbohydrate digestion. The optimum pH for its working is 6.8. As the bolus enters the stomach, pH drops drastically. Gastric juice has pH around 3. Salivary amylase is not able to function in such a low pH and becomes inactive in stomach. As a result, carbohydrate digestion halts in stomach. Gastric juice has its own amylase but it does not digest the starch much.

As the bolus enters the small intestine, the acidic pH is restored to neutral value. Carbohydrate digestion restarts with the help of pancreatic amylase.