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Dylan Han(6) 2-5 Topic Chosen 1: Digestion Topic Chosen 2: Issues on Sex Links and Credits linkone linktwo Layout: hearteditorials Codes: -ambulance Icon: biconcave |
Sunday, June 29, 2008
E-learning Day 3: 29 June 2008
Greetings. Once again, I will be writing an entry on a digestion-related topic which is derived from a question formulated. How is it possible for a person to swallow food even in space despite the lack of gravity? First, I decided to search http://wikipedia.org/ for an article relating to how the oesophagus, or else known as the gullet, manages to allow a person to swallow food. Basically, according to Wikipedia, the oesophagus (American spelling: esophagus) is an organ in vertebrates that consists of a muscular tube through which food travels from the pharynx (part of the throat directly behind the mouth and nasal cavity) to the stomach. From this, I am able to make a vague guess that gravity is not required in the process of swallowing since the oesophagus is a muscle and is able to make use of muscular effort to transport food. However to be sure, I decided to research on the process of swallowing. To obtain the relevant information, I referred to http://wikipedia.org/ and http://answers.com/. Firstly, the food which enters the mouth is masticated into small chunks by the teeth and mixed with saliva to form a food bolus. This is then transferred to the oesophagus when modified to an appropriate size through movement of the tongue and the chewing of the jaw. The food bolus is pushed backward by the tongue against the roof of the mouth. The kinetic energy forces the bolus into the pharynx. Circularly-arranged muscles in the pharynx contract repeatedly, causing the food bolus to travel down the oesophagus into the stomach for digestion. However, swallowing is complicated by the position of the airway leading from the nose to the larynx within the pharynx. Therefore, human adults are unable to inhale or exhale at exactly the same time they swallow and have to time these properly. Above, gravity was not listed as a factor that would affect swallowing. Therefore, it is safe to conclude that swallowing food in space is possible, which explains how astronauts eat in space. However, oesophagus of most birds are merely "chutes" that rely on gravity to transport the food to the stomach. In fish, water is utilised to pump food towards the pharynx and the water is transferred out of the gills. Therefore, it is inadvisable for birds or fish to swallow food in outer space as it is impossible for them to do so. Oesophagus (including other organs of the body):  Sources: http://en.wikipedia.org/wiki/Esophagus http://en.wikipedia.org/wiki/Swallowing http://www.answers.com/swallowing?cat=health http://www.sts.org/graphics/patientinfo/colorstomach-esophagus.jpg |
