Nutrition and Digestion - Digestive System

Running head; NUTRITION AND DIGESTION
NUTRITION AND DIGESTION
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NUTRITION AND DIGESTION1
Introduction
Understanding the structure and function of the digestive system assists in understanding
how diet is closely associated with nutrient consumption and overall health outcomes (Gazouli
and Theodoropoulos 2019). The following paper will extensively and elaborately discuss on the
major structures and functions of the digestive system as well as how food tests can determine
the nutrient quality of specific food items in the diet.
Discussion
Structure and Function of Alimentary Canal
The alimentary canal comprises of a long tube which begins from the mouth and extends
till the rectum and comprises of a number of accessory glands and organs (Boland, Golding and
Singh 2014). The following are the key structures which can be found in the alimentary canal
along with their associated functions (Williams 2015). These have highlighted in Figure 1.
 Mouth and Oral Cavity: The digestion of food begins in the oral cavity or mouth which
comprises of structures like teeth, salivary glands and the tongue. The teeth masticates
food into small particles while the tongue mixes the food with salivary. Salivary glands
produce saliva which break down starches in the food by amylase enzyme. The tongue ad
epiglottis then pushes the bolus towards the throat down the esophagus.
 Esophagus: Longitudinal and circular muscular structures perform peristalsis by
constructing the esophageal structure front and behind of the food to push food further
towards the stomach.
 Stomach: The stomach comprises of three structural regions, known as the cardiac,
fundus and pylorus. Food enters the stomach through the cardiac sphincter. Food

NUTRITION AND DIGESTION2
undergoes digestion by the stomach via secretion of gastrin from the fundus region while
the cardiac regions secret mucous to protect the stomach lining from being damaged by
acids. Once the food has been churned and mixed to form chime, it is then pushed
towards the intestines by the pyloric sphincter.
 Small Intestine: The small intestine contain structures like the duodenum, jejunum and
ileum. The duodenum receives bile salts and enzymes from the pancreas which break
down fats, carbohydrates and lipids in the food. Villi or small finger like structures lining
the small intestine absorb nutrients released from the food during digestion to be
transported via circulation to the cells and issues.
 Large Intestine: Food which remains undigested travels to the large intestine where
water is absorbed and undigested epithelial cells, bacteria and fiber undergo storage in the
rectum for excretion by the anus (Williams 2015).
Figure 1: Structure of the Digestive System