Fantastic Voyage

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Fantastic Voyage

The journey through the gastrointestinal tract was quite enjoyable and fantastic especially due to the organs that I passed through and the events taking place, which start from the mouth. It was quite interesting to find that some food materials are digested in the mouth by saliva and upon reaching the stomach through the esophagus, they are absorbed into the bloodstream. In addition, it was interesting to note that alcohol is absorbed into the bloodstream upon arrival at the stomach. In the mouth, the teeth breakdown the big particles of the food by grinding it, the tongue turned the food particles to ensure that all of it was fully broken down while the saliva acted as a moistener and an enzyme that digested the starch. After the food is chewed, it is formed into a bolus ready to be transported further in the journey. In the mouth, the digestion started and as I went further with my journey, I arrived at the pharynx, an opening that led me to a hollow muscular tube, which I found out to be the esophagus. In this tube, the broken down food particles went down through a process that involved the muscular lining contracting in wave like manner, pushing the bolus down and I found out that this process was called the peristalsis.

Peristalsis pushed the food down, passing through the liver, went down deeper and through a thin lining that is the diaphragm until another point, which was pouch like and I realized this was the stomach and more food kept coming with more having already arrived before me. On the lining of the stomach, before much food comes in it was a little folded. I realized that this was the rugae as more food entered; the rugae straightened giving more space. The stomach produced a chemical fluid, which is the gastric juice or acid, that mixed with the food with the help of the muscular lining of the stomach that helped to ensure all the food was grinded further into finer particles, which at the end of the second hour, had turned the food into a thick liquid. I wondered how the stomach managed to stay without being digested by this acid, and I found out that it secretes a bicarbonate fluid from the epithelial cells in the thick mucosa lining covered by mucus and neutralizes the acid, hence forming water that prevent self digestion. To the end of the stomach, a small opening led to another point.

Upon going through the opening, I realized it was the path to small intestines, which was called the pyloric sphincter. As I went through, I realized that carbohydrate food was emptied faster into the small intestines, followed by the proteins, which needed more time to be digested in the stomach and fats were the last. I realized that the wall of this structure had four coats, the serous, which surrounds almost all part of the duodenum. The other was the muscular coat that had two layers of unstriped fiber, a longitudinal one that is external and an internal layer that was circular. The third coat, areolar connected the mucous and muscular layers, and has blood vessels, while the fourth, mucous membrane was highly vascular and thick, at the upper part of the intestines. I also realized that this structure was highly folded, making it about six meters long. The intestines had small projections called the villi that further had projections on them, which were called the microvillus. The villus contains many blood vessels in them. Once the food entered the small intestines, the pancreas produced a juice that was rich in enzymes that broke down the food further into finer particles. Other enzymes were produced from the liver, the bile juice, which was squeezed into the intestines through the gall bladder to digest the fats. After the food was fully digested, it was then absorbed through the villus, which had specialized cells to allow the food materials to pass through the mucosa and into the blood stream (National Digestive Diseases Information Clearinghouse, 2008). Further, down at the ileum of the intestines, a vessel called the Superior Mesenteric Vein served as a route of the food absorbed at this part to the blood stream. From the distal ileum, I passed through the mucous membrane and into the blood stream as I entered the superior mesenteric vein.

The path through the superior mesenteric vein was interesting, as one viewed the muscular lining of the vein, and from this vein, I entered the hepatic portal, which was joined by the splenic vein too. I followed the path, which led to the main vein, vena cava that took blood to the heart, the first entry being the right auricle, which passed the blood to the right ventricle, where the blood was pumped to the lungs via the pulmonary artery. At the lungs, the blood exchanged gases and I followed to the pulmonary vein that took the blood back to the heart and in the left ventricle, the blood was pumped into the body through the aorta. I chose to follow the abdominal aorta and finally to the left renal artery.

Through the left renal artery, I entered the kidney through the glomerular membrane where I found myself in one of the nephrons and I entered the Bowman’s capsule to witness cleaning of the blood. Once in the Bowman’s capsule, I observed a twisted region, which I found out to be the proximal tubule. After that, there was a long narrow tube extended from the cortex to the medulla and back, which was the loop of henle, where the one going deeper inside was the descending one while the other was the ascending. The pressure in this tubule forced the water, urea and salts out of the blood into the capillary walls and this fluid went through the loop of henle (Ciba Foundation Symposium., 2009). The important water and salts were absorbed back into the blood stream, while the unwanted wastes were left in the glomerular fluid and are passed to the ureter, which takes them to the urinary bladder. The blood is absorbed back to the renal vein. I followed the path to the bladder and through the sphincter muscle at the end of the bladder, I found my way out through the urethra.

From my journey, I observed that the body manages to maintain a balance of functions through the circulatory, digestive and the urinary systems. When the food is digested in the gastrointestinal tract, it is absorbed into the blood stream and taken into the body cells, where the nutrients are used up and waste is taken back into the blood stream, which takes it to the kidneys, and the filtration removes the waste materials that are passed as urine. Still, from my observations, I realized that the digestive system also secrets wastes of the indigestible materials through egesting it through the large intestines and finally through the anus. The circulatory system also plays a crucial part in maintaining homeostasis through secreting waste as sweat, when it is hot and when it is cold, since much of the blood vessels retrieves away from the superficial layer and waste is secreted through the urinary system. This maintains a balance in which the body functions ultimately without influence by environment and hence equilibrium is maintained (Schulkin 2003). I also noted that temperatures in the body are maintained by these systems and that homeostasis involves marinating a balance in all the body functions irrespective of conditions prevailing.

References

Ciba Foundation Symposium. (2009). The Kidney. Hoboken, NJ: John Wiley & Sons Inc

National Digestive Diseases Information Clearinghouse. (2008). Your Digestive System and How It Works. Retrieved from http://digestive.niddk.nih.gov/ddiseases/pubs/yrdd/

Schulkin, J. (2003). Rethinking Homeostasis: Allostatic Regulation in Physiology and Pathophysiology.Cambridge, MA: MIT Press.