ESSAY: Gastrointestinal System

1. Discuss the process of digestion by explaining the following:

• Where does it begin?

• What are the roles and functions of saliva, the stomach, and the accessory organs?

ANSWER

Gastrointestinal System

            A digestive system is a unique system made up of gastrointestinal tract and its associated accessory organs, which is responsible for food processing, nutrients absorption, and waste elimination. The gastrointestinal tract, also known as GI tract or digestive tract, is an organ system within humans and some animals that take food, digest it to extract and absorb nutrients and energy, before it expels the remaining foods (wastes) as feces (McErlean, 2016). The gastrointestinal system is made up of organs such as the mouth, esophagus, the stomach, and small and large intestines, including the anus (McErlean, 2016). The digestive system is also made up of solid organs such as the pancreas, liver, and gallbladder.

           Digestion starts in the mouth following the secretion of digestive enzymes and saliva. Food particles are then formed into boluses through a mechanism known as mastication before it is swallowed through the esophagus. It is in the esophagus region that food enters the stomach via a peristalsis action. Pepsin and hydrochloric acid make the gastric juice, and they have the ability to damage the stomach walls, thus mucus is constantly released for protection (McErlean, 2016). More secretion of enzymes is made in the stomach for a further breakdown of food. This is combined with the stomach’s churning action.

           Food partially digested enters the duodenum. The region receives food products as a semi-liquid, thick chyme. The chyme enters the small intestines, a region where significant digestion process takes place. In it is this region that the digestion process takes place with assistance from the secretion of bile, intestinal juice, and pancreatic juice (McErlean, 2016). The intestinal walls are made up of features known as villi. Their epithelial cells are covered with numerous microvilli to boost the absorption of nutrient contents from the chyme. The numerous microvilli facilitate a faster absorption process as it increases the small intestines’ surface area. In the large intestine, food passage tends to be slower compared to the small intestine to give more time for fermentation by a gastrointestinal microbiota in humans known as gut flora to take place. It is in this region that the absorption of water takes place. The waste food products are also stored as fecal matter in this stage before the material is removed via the anus or anal canal by defecation.            The salivary glands make up the accessory organs. Salivary glands generate watery secretions known as saliva. Indigestion, saliva is…