The pathway of food through the digestive system.

The first 200 words of this essay...

Assignment 1

The pathway of food through the digestive system

The first phase is ingestion. This is when food enters the mouth and is chewed into small pieces. Saliva from the salivary gland pours into the mouth. This contains the enzyme amylase, which begins the process of digestion by breaking down starch into simple sugars. The tongue rolls the food into a ball called a bolus, which is pushed to the back of the throat.

The food passes through the throat into the Oesophagus. The bolus is squeezed down the Oesophagus by muscular walls. The gut contracts above the bolus and relaxes below the bolus so that the food is passed down through the Oesophagus into the stomach by waves of contractions called peristalsis.

When the food enters the stomach the muscular walls contract and relax to churn and mix up the food. The stomach produces hydrochloric acid for two reasons, firstly to kill any bacteria that might be in the food and secondly to provide the correct pH for the protease enzymes to work. The enzyme protease works best at pH 2. The protease enzyme is produced in the stomach. Protease begins the digestion