Digestion, absorption and metabolism

Purpose and Components of the Digestive Tract

The purpose of the digestive system and its components is to break down and process nutrients and energy so the body can use them to function. The digestive tract consists of the esophagus, stomach, small intestine, large intestine, rectum and anus along with the liver, gallbladder and pancreas which make up the gastrointestinal tract. All of these organs coordinate with bodily processes to digest and allow the nutrients and energy from the food we eat pass through the body which sometimes takes a day or two to receive them. The purpose of the digestive system is to break down complex food particles into smaller products which make it easier to digest and absorb. The process of digestion and its purpose is to break down food into finer particles which can be used as energy and nutrients for the benefit of the entire body to function properly.

The Mechanical Aspect of Digestion

The job of the digestive system is to break down larger pieces starting in the mouth where there are teeth and saliva offer the job to chew and add saliva which contains the enzyme amylase which allows it to break down starches and fats along with different enzymes. This allows for an easier journey through the passageway called the esophagus which directs it towards the stomach and then onto the small and large intestines which have different functions producing different enzymes to further liquefy food through a series of muscular pulses called peristalsis which involves waves and squeezing action to push the liquefied mass into what is called chyme. The small intestine is where digestion and absorption happen. The stomach and intestines add water to add fluid to move things more easily along. Small intestines also secrete enzymes that digest carbohydrates, fat and protein. Before entering the stomach, there is a circular opening called the sphincter which is narrow and acts as a gateway to help keep contents from creeping back towards the esophagus. Unlike the esophagus, which simply ensures the prompt passage of a bolus, the stomach receives nutrients, retains them and submits them to a series of mechanical and chemical processes before delivering them into the intestine for further digestion and absorption (Schulze, 2015). At this point the body has broken down starches and proteins, this leaves through to the large intestine which reabsorbs water and minerals and passes waste products and any other non-absorbed nutrients onto the rectum via the colon. It mechanically extracts fluid from the chyme the small intestine delivers into it, and compacts chyme, cellular debris and other waste products into feces (Schulze, 2015).

The Chemical Aspect of Digestion

Digestion begins in the mouth where saliva breaks down starch and some fat. It enters the stomach where proteins such as in the food source, salmon, happens by releasing chemicals called gastric juice, a mixture of water, enzymes and hydrochloric acid which is strong enough to initiate digestion of this protein. It has a high enough ph balance to do this job in digestion and in the stomach this is its main function. There are specialized cells that act as a barrier or mucous lining in the stomach which protect the digestive tract lining so it does not become digested through this process and protects the cells from exposure to these strong juices by a mucous membrane lining. When food enters the small intestine hormones send signals to the gallbladder to contract and squirt the right amount of bile, which acts as an emulsifier into the intestine (Sizer & Whitney, 2017).  Other hormones signal the pancreas to release pancreatic juice which contains the alkaline compound bicarbonate in precise amounts to neutralize the stomach acids.

Side Note

Eating too fast or too much can cause digestion difficulties as it can cause heartburn and other complications. The best thing I can do to avoid complications due to digestion is to eat in an unstressed and relaxed pace and to watch what I eat. When introducing new items to my digestive tract I should use precaution, perhaps small amounts at first to send through the system as a sort of trial. Overeating or drinking causes heartburn which results in gastric juices backing up into the esophagus where it burns a less protected surface. More importantly, it is crucial for me to chew food carefully, choking on food when eating too fast or talking or laughing when eating has caused this to happen especially in the morning when I am gulfing down hard boiled eggs. It is a good idea to slow down as well as keep up with dental checkups to make sure my teeth are in good shape to allow for functional chewing and tearing of food into smaller more manageable pieces. Constipation can be a problem and it is important to remember to drink enough fluids, eat enough fiber and maintain a regular scheduled bathroom visit as if we are in a rush or try to hold off going when it is time it can cause the colon to extract water from the feces the longer we wait (Sizer & Whitney, 2017). Constipation can lead to hemorrhoids which are painful and annoying. Relying on laxatives can cause dependency so it is best to have a good diet, drink enough water and get the physical exercise to allow for the colon to stay in shape as well as being a benefit to diet and physical wellness (Sizer & Whitney, 2017). Our bodies are amazing machines that function well if kept in good order by having healthy eating habits and lifestyle. It is flawlessly designed to digest and absorb food. Through observance of what we eat, how we eat, why we eat and where we eat, the digestive tract can stay fit and healthy and keep us going for a long while and reducing the chances of causing it harm. 

Schulze, K. S. (2015). The imaging and modelling of the physical processes involved in digestion and absorption. Acta Physiologica, 213(2), 394-405. doi:10.1111/apha.12407

Sizer, F. & Whitney, E. (2017). Nutrition: Concepts and controversies (14th ed.). Mason, OH: Cengage Learning.

ISBN-13: 978-1-30563937-9, ISBN-10: 1-305-63937-5

https://www.healthline.com/medical-team

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