Digestion and Absorption
To begin with, the purpose of the of the digestive system is to “digest and absorb the complex mixture of chewed and swallowed food.”(Sizer & Whitney, 2012). The digestive tract is a flexible, muscular tube which is about 26 ft in length and begins at the mouth and continues through the throat, esophagus, stomach, small intestine, large intestine, rectum and ultimately the anus. Interestingly enough when a person swallows something it does not automatically enter into the body, but actually sits inside the inner portion of the tube until a nutrient or other type of substance passes through the wall of the digestive tract. Simply stated, the digestive tract is the highway from the mouth to the anus that allows the body to take in nutrients and expel non-nutrients also known as waste through mechanical and chemical processes.
If a person were to eat a hamburger there is a mechanical process that will take place in order for full digestion to occur. Once the hamburger is bitten, the process of chewing the food into smaller parts occurs. It is the chewing that not only breaks the food down, but causes saliva to occur which creates water that softens the hamburger to prevent any type of cutting of the esophagus and also moistens the food, thus allowing for easier passage down the esophagus to prevent possible choking. The tongue then pushes the food down the pharynx, where the food goes down the esophagus and enters the stomach through peristalsis also known as involuntary contractions. Once the food reaches the stomach and the intestines it is their job to hold the bitten hamburger until it is liquefied through mashing and squeezing actions and then move the food through the digestive tract which is done through a series of wave like motions called peristalsis. Once the food leaves the stomach and enters the small intestine, nutrients that the body needs are absorbed and what is left is mostly water and indigestible waste products. These leftover items then enter the colon whose main job is to remove water from the waste products, recycle the water back into our body; thus preparing for the waste to expel through the anus.
Incidentally, the difference between the mechanical digestion and chemical digestion is mechanical digestion is the physical process of breaking down food and chemical digestion is the process of breaking down foods by substance, compound or elemental enzymes. For example, many organs that make up the digestive system secrete certain special fluids that allow for the complex chemical processing of digesting the food that we eat. Using the hamburger as an example, once it is in the digestive tract, there are enzymes in the digestive fluids that break down nutrients into their component parts. Once the food passes through the mouth, the pharynx, and esophagus and reaches the stomach, the process of mixing and grinding begins. Here is where the digestive chemicals after mixing and grinding create a substance called chyme. Once the foods are broken down into proteins, which is the main function of the stomach, the process in the small intestine begins. The small intestine acts as a message center to the other organs such as the pancreas and the gallbladder. The small intestine needs bile, and pancreatic juices to neutralize the stomach acids so that the large nutrients can be held together while the smaller pieces are released into the intestinal fluids ultimately becoming so small that the nutrients can be absorbed into our body’s cells for use via our bloodstream, while the remainder of makes its way to the colon. The colon is the last stop in our food’s journey and this is where the liquid is removed from the non nutritive food waste causing it to become solid and ready for excretion.
The role of the organs associated with the digestive tract is to analyze the nutrients that are consumed and then create and deliver digestive juices and enzymes appropriate for digesting. These organs and their enzymes ensure that foods of all types are used fully by the body. “Enzymes are important in food processing for a variety of reasons but particularly because of their high substrate specificity, rapid reaction rates and ability to work effectively at relatively low temperatures and under mild conditions.”(Tucker, G., 1996). So if we eat foods high in sugars and carbohydrates, these organs are smart enough to create sugar and carbohydrate digesting enzymes. Simply stated, this means that we are what we eat. If we eat sugar, our body breaks it down and puts it back into our cells as nutrients so it comes as no surprise that there is a strong correlation between food choices and digestive disorders.
Mechanically if we eat too fast, then we get the hiccups, chemically if we eat and or drink foods that are high in chemicals such as chili peppers, alcohol, coffee and or chocolate we then have to deal with heartburn, ulcers and reflux disease. “Gastroesophageal Reflux Disease (GERD) is disruptive and places a great clinical and economic burden on patients and society as a whole.”(Moosavi, Teimoori, & Ghourchian, 2012). The key to avoiding disorders is listening to one’s body; not taking it for granted; and avoids self diagnosing problems by going to the doctor.
In summary, digestion and absorption is a vital biological part of the body function because without the ability to process foods, extract nutrients, and eliminate waste every part of our body would cease to function. Furthermore, most individuals do not understand what comprises the digestive tract, the mechanical and chemical processes because if they did understand a person would be more careful not to choose foods that cause discomfort when eaten. Indeed, even the smallest problems that occur within our digestive system can result in harmful and unwanted situations such as nutrient deficiencies, fatigue, and significant discomfort such as indigestion and acid reflux; hence the importance for an individual to not take for granted this most important process.
First of all, I wanted to gain a better understanding of what the purpose of fat was for our body since I really never knew what it was for. I thought it was used to keep us warm. However, when I read a text pertaining to health, it stated, “Fat is the body’s chief storage form for the energy from food eaten in excess of need.”(Sizer & Whitney, 2012). In addition to storing energy, fat also provides the much needed energy to perform the body’s work, especially muscular work as well as providing padding around our body’s organs. Now it is up to us to understand which fats are good for us and which ones are not.
The various types of fats are good fats and bad fats. The good fats increase the good cholesterol and decrease the bad cholesterol. The bad fats decrease the good cholesterol and increase the bad cholesterol. The good fats are the unsaturated fats also known as monosaturated or polyunsaturated fats and examples of foods with good fat are avocados, nuts and salmon; while the bad fats are Trans or saturated fats and examples of these foods are red meat, butter, and cakes.
Trans fat is believed to be harmful as these fats are believed to cause harmful diseases such as cancer or heart attacks along with the harmful side effects of becoming obese. Saturated fatty acids and trans fatty acids worsen the blood lipid profile and these blood lipids play key roles in our body functionality that involve cell membranes, the bile process, and inhibiting cholesterol absorption. In addition, saturated fatty acids also contribute to blood clotting which are associated with heart attacks. I learned that a person can generally judge a good fat based on its hardness and this can be determined by how liquid the fat is at room temperature. Here is where I envision liquid fat going through my body or a lard like tough substance clogging my arteries and quite frankly, I would rather picture liquid fat flowing through my body.
The connection between dietary fat, cholesterol and fat is that when a person consumes too much dietary fat there is a high association with cardio vascular diseases which is the number one killer of adults in the United States and Canada. Elevated blood cholesterol is a risk factor for cardiovascular disease and one of the main reasons for the increase in blood cholesterol is due to the consistent consumption of foods that have saturated and trans fat.
The importance of protein in maintaining a healthy diet is first of all protein is quite the important nutrient as the body needs substantial amounts of it to function properly. Protein is our body’s chemist which allows the body to create hormones, enzymes, and other chemicals required by the body. “Amino acids must be continuously available to build the proteins of new tissue. The new tissue may be in an embryo; in the muscles of an athlete in training; in a growing child; in new blood cells needed to replace blood lost in menstruation, hemorrhage, or surgery; in the scar tissue that heals wounds; or in new hair and nails.”(Sizer & Whitney, 2012). . Although our bodies produce amino acids, protein also provides the body with vital amino acids which come from the protein found in the foods that we eat.
The protein recommendations for healthy adults according to the DRI are 0.8 gram protein per kilogram of body weight per day. The female intake is 46 grams per day and the male intake is 56 grams per day and the about 10-30 percent of calories should come from protein. It is important to consider other factors such as the body and food sources when determining an individual’s protein need. Perhaps a marathon runner needs more protein, or a person who is a vegetarian may need more protein as well and these things need to be considered.
I would like to believe that I meet the above requirements and the best way I feel that I am meeting these requirements is not by determining and calculating what specific proteins I eat as that is just too hard for me. The way I can determine the requirements is by the fact that my hair and nails grow very quickly; when I have a cut or a minor injury it heals very quickly and my body mass index (BMI) results were right in line with where they needed to be.
Moosavi A., Raji, H., Teimoori, M., & Ghourchian, S. (2012). Air column in esophagus
and symptoms of gastroesophageal reflux disease. BMC Medical Imaging, 12(1),
Sizer, F.S. & Whitney, E. (2012). Nutrition concepts and controversies. (12th ed.). Belmont, CA: Wadsworth, Cengage Learning
Tucker, G. (1996). Biotechnology and enzymes in the food industry. British Food Journal, 98(4), 14-19. Retrieved from http://search.proquest.com/docview/225150914?accountid=32521
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