The human digestive system comprises of a long continuous conduit known as a gastrointestinal tract that extends from the mouth to the anus. It consists of a number of organs and auxiliary structures which processes food (process known as digestion), both mechanically (using muscles) and chemically (using digestive enzymes) into smaller water-molecules, e.g. sugars, which are then absorbed into the body which are then be utilised by the body to produce energy and other nutrients which the body requires to survive.
The process of obtaining nourishment is instigated by the ingestion (intake) of food and/or liquid entering the gastrointestinal tract through the mouth. In the mouth, the food will encounter the tongue, which will analyse the ingested material to see if it safe for the body to consume or if it needs to be rejected (toxic or poisonous). The sensory receptors on the tongue detect sweet, salt, bitter and sour taste and this stimulates the three pairs of salivary glands to produce saliva and secrete it into the mouth. Saliva is a water-based liquid that contains mucus and enzymes, …show more content…
This is a globular mass of partially digested materials. This ensures that the ingested material is slippy and easy to swallow. The tongue then moves the bolus towards the pharynx, a muscular conduit, during swallowing. The pharynx is shared with the ingested materials and liquids, going to the stomach, and air, going to the lungs. A flap of cartilage at the back of the tongue, called the epiglottis, prevents ingested materials from entering the trachea. Muscles in the wall of the pharynx push ingested materials into the oesophagus. The oesophagus is a narrow muscular tube that uses peristalsis (contraction of the muscles in waves) to transport the bolus and any liquids from the pharynx to the stomach. No digestive processes take place in the