Structure and Functions of the Digestive System

Running head: BIOLOGY 1
Biology
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BIOLOGY 2
Introduction
The digestive system contains the gastrointestinal tract along with the accessory
digestive organs that operate together to chemically and mechanically digest food, absorb water
along with nutrients and eliminate wastes. Its functions include ingestion, digestion, absorption,
assimilation, and egestion. This essay explains how the structure of each organ of the digestive
system relates to these functions.
Ingestion is the consumption of substances through the mouth into the gastrointestinal
tract. The structures of the mouth which are muscles, mechanical and chemical action and moist
relate to ingestion (Iguchi et al., 2015). The cheeks make up the side walls of the mouth, and
their outer covering is skin while their inner coating is a mucous membrane. In between the skin
and the mucous membrane are connective tissues and buccinators muscles whereby these
muscles along with orbicularis oris muscle in the lips contract helping the food when being
chewed not to fall out of the mouth.
In the mouth, food is broken down by a crushing action by teeth into small pieces and
then moistened by saliva which is secreted by the parotid, sublingual and submaxillary glands
(Iguchi et al., 2015). The epiglottis averts food from entering the larynx at the upper part of the
respiratory system, and once the food is swallowed, it flows through the esophagus which is long
and by a series of muscular contractions known as peristalsis it reaches the stomach. In the
esophagus, there is no digestion that takes place.
Another function of the digestive system is digestion which occurs in the stomach
(O'Connor & O'Moráin, 2014). It is referred to as the breakdown of large insoluble food particles
into small water-soluble food particles so that they can be absorbed into the watery blood