On pg. 98-99, Dr. Moalem describes how the friendly bacteria gut flora in the digestive tract helps maintain homeostasis in the body by working with many different organ systems, and performing many different functions. This relates to Big Idea 4: Biological systems interact, and these systems and their interactions posses complex properties.
Describe the various roles of gut flora and identify other bodily systems these bacteria interact with and how they do so. Identify the significance of each interaction by explaining how it helps the body maintain homeostasis and predict possible consequences if the interaction were to function improperly. Also describe ways to restore the friendly bacteria that are killed by antibiotics. Finally research the phenomenon Dr. Moalem describes as the barrier effect, a way the gut flora keeps harmful bacteria under control. Identify specific types harmful bacteria that are controlled by the barrier effect, and explain on a molecular level how the barrier effect can prevent harmful from overloading the digestive tract.
(Posted by Raymon Cao; racao4@students.d125.org)
Gut flora refers to the network of friendly bacteria that reside in our digestive tract. The gut flora have many different roles. Gut flora are important in digestion, repressing pathogens, and immunity.
ReplyDeleteWhen we eat, chemicals and the bacteria in our digestive tract break down the food molecules. The gut flora are especially important in breaking down carbohydrates. Some gut flora contain enzymes to break down certain polysaccharides that regular human cells lack. Some carbohydrates that we cannot digest without gut flora include some starches, fiber, and sugars. If the gut flora were to function improperly, our bodies would be unable to harness some of the carbohydrates we consume, resulting in less available energy for our bodies. Also, improperly functioning gut flora could lead to uncomfortable or painful symptoms of the abdomen, including bloating, cramps, diarrhea, flatulence, and inflammatory bowel disease. For example, if someone has lactose intolerance, then his or her body is unable to properly digest and absorb lactose. This is due to a lack of the enzyme lactase in the bacteria of the digestive tract. As a result, when this person consumes a food product containing lactose, he or she may experience abdominal pain, diarrhea, bloating, cramps, etc.
Gut flora are also important in the repression of pathogenic growth. The helpful bacteria prevent harmful pathogens from growing through competitive exclusion. According to the Campbell text, “in the absence of disturbance, one species will use the resources more efficiently and thus reproduce more rapidly than the other. Even a slight reproductive advantage will eventually lead to local elimination of the inferior competitor” (1199). The gut flora attach to the mucosal lining of the intestines, and they compete for nutrition and space to attach to the mucosal lining. The helpful bacteria are more accustomed to the environment of our intestines, so they are generally more successful in the competition with the bad bacteria. This competition is known as the barrier effect. Without gut flora, we would get infected very easily because the bad bacteria would be free to proliferate and spread throughout our bodies. This relates to Big Idea 4: Biological systems interact, and these systems and their interactions possess complex properties.
Lastly, the gut flora are very important to the immune system. According to ScienceDaily, “signals from natural intestinal bacteria are necessary for an effective immune response to various viral or bacterial germs”. ¹ They are important in the early development of the gut’s mucosal immune system, which is part of the body’s first line of defense. The helpful bacteria stimulate the lymphatic system tissue associated with the gut mucosa to produce antibodies. Without the helpful bacteria, our bodies would be less effective at producing antibodies, and therefore our immune response could be too slow to fight off harmful pathogens. Also, changes to our gut flora “can increase the risk of food allergies or chronic inflammatory intestinal diseases” ¹
Taking antibiotics not only targets the bad bacteria, but also alters the amount of helpful gut bacteria. This can affect the body’s health and ability to digest food. When the number of gut flora in the digestive tract is decreased, it makes it more difficult to repress pathogens. If the body isn’t as efficient at fighting the bad bacteria, the bad bacteria can grow to dangerous numbers and lead to disease. Also, digestion is affected because with lower numbers of gut flora, the body is less efficient at metabolizing bile acids and fermenting carbohydrates. All of these can cause diarrhea. Helpful bacteria thrive on fiber. A way to restore these friendly bacteria is by taking probiotics. Probiotics can be found in fermented foods like yogurt, kefir, kim chi, etc, or can also be taken in the form of supplements. Though probiotics don’t replace natural gut bacteria, they act as placeholders until the native gut flora can regenerate to healthy levels.
ReplyDeleteAs mentioned previously, the gut flora are part of a phenomenon called the barrier effect. The barrier effect is the repression of pathogenic microbes by the gut flora due to competitive exclusion. The adherence of the gut flora to the mucosal lining of the intestines and the competition for nutrition inhibits the growth of harmful bacteria. The barrier effect protects our bodies from harmful yeasts and bad bacteria such as Clostridium difficile. These bad bacteria are normally unable to compete with helpful bacteria for nutrients in the gut and space to grow along the mucosal lining. Without the barrier effect, the bad bacteria would be able to attach to the mucosal lining, and grow and invade our bodies, resulting in an infection.
1. http://www.sciencedaily.com/releases/2012/07/120702152940.htm
(Sarah Terwilliger, sterwil3@students.d125.org)
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