Digestion From Beginning to End - Essay Example

Digestion, From Beginning to End The food we eat contains carbohydrates, proteins, fats, and other nutrients. As part of the process of food digestion, the different enzymes amylase, maltase, lactase, urease, pepsin, trypsin, nucleases, and DNA polymerases such as act as biological catalysts in the human body. In general, mechanical digestion occurs in the mouth and mastication occurs when a person starts to chew and grinds the food using the molars and premolars. As the tongue moves around the food inside the mouth when chewing, the soft palate closes the nasal passages and airway so that the food stays inside the mouth.

Located on the anterior part of the hard palate, the rugae facilitate the movement of food backwards towards the pharynx. (See Appendix I to IV – Nutritional Contents of Double Cheeseburger, French Fries, Chocolate Shake and Apple Pie on pages 4 to 7)Among the types of food that is rich in carbohydrates include a double cheeseburger, French fries, apple pie, and double thick chocolate shake. Secreted by the salivary glands, the presence of salivary amylase or ptyalin inside the mouth aims to catalyze the hydrolysis of starch molecules or carbohydrates into simple sugar such as maltose.

After the carbohydrates are broken down by the salivary amylase, the next digestion of carbohydrates will take place inside the small intestine when the pancreas releases some pancreatic amylase. On the other hand, the intestinal mucosa secretes maltase and lactase enzymes which are responsible in converting maltose to glucose, and lactose to glucose and galactose respectively. For easy swallowing, the saliva contains mucin which acts as a lubricant. When swallowing the food, the epiglottis prevents the food from entering into the trachea.

Eventually, the bolus will pass through the esophagus before entering the stomach.A double cheeseburger, French fries, apple pie, and double thick chocolate shake are also rich in fats and protein. As part of the chemical digestion that takes place inside the stomach, the enzyme known as the gastric lipase breaks down fats whereas the gastric protease or pepsin breaks down the protein. After the stomach muscles further breaks down the food and mix it with gastric juice, the food moves into the duodenum through the pyloric valve.

At this point of digestion, the food is already known as the chyme. In most cases, the pancreatic and bile ducts open into the duodenum at a point close to pylorus. When the gastric gland secretes gastrin or gastric juice, the hydrochloric acid (HCl) that is present in the gastro secretion kills the bad bacteria present in the food. Without affecting the good bacteria, HCl also aids in converting inactive pepsinogen into active pepsin. Basically, the pepsin breaks down proteins into peptides.

In case the gastric gland releases too much HCl, the pancreas releases sodium bicarbonate in order to neutralize some of the excess acid that is present in the chime. Most of the chemical digestion occurs in the small intestine. As part of the digestion that takes place inside the small intestine, the liver secretes bile acids which play a significant factor in the digestion and absorption of fats and fat-soluble vitamins. Most of the food digestion that takes place inside the small intestine is possible due to the presence of the pancreas.

Major organs and enzymes that assist in the food digestion that occurs in the small intestine includes the pancreatic juice that is secreted by the pancreas, the intestinal juice secreted by the small intestine, and the emulsification of fats or lipids coming from the gall bladder and the liver. In line with this, the pancreatic amylase or amylopsin secreted by the pancreas is responsible in converting starch into maltose, the pancreatic lipase which is secreted by both the gastric mucosa and the pancreas is responsible in splitting fats into fatty acids and glycerol, and the pancreatic proteases wherein the pepsin secreted by the gastric mucosa is responsible in splitting the proteins into proteoses and peptones; trypsin secreted by the pancreas is responsible in splitting proteins into peotesos, peptones, polypeptides, and amino acids; and the erepsin secreted by the intestinal mucosa is responsible in splitting perptones to amino acids and ammonia.

The large intestine removes some water and electrolytes from the food whereas the ileocecal valve makes it possible for the food to pass from the small intestine into the large intestine. In line with this, the food will enter the large intestine via cecum, the ascending colon and transverse colon before it enters the descending colon. The bile acid is responsible in segregating the waste products which will exit the human body as feces via anus.Appendix I – Nutritional Facts of Double CheeseburgerSource: Nutrient Facts aAppendix II – Nutritional Facts of French FriesSource: Nutrient Facts bAppendix III – Nutritional Facts of Apple PieSource: Nutrient Facts cAppendix IV – Nutritional Facts of Chocolate MilkshakeSource: Nutrient Facts dReferences"Nutrient Facts." 2012a. Double Cheeserburger.

21 July 2012 ."Nutrient Facts." 2012b. French Fries. 21 July 2012 ."Nutrient Facts." 2012c. Apple Pie. 21 July 2012 ."Nutrient Facts." 2012d. Chocolate Milk Shake. 21 July 2012 .Total Number of Words: 763