How Do Humans Benefit From Bacteria Living in the Digestive System?
Jul 21, 2011 | By Suzanne Robin
With the advent (creation) of probiotics sold as health supplements, it has become common to refer to bacteria in the intestinal tract as "good" bacteria or "bad" bacteria. The average person hosts around 100 trillion bacteria in the gut, according to the Harvard Medical School Family Health Guide. "Good" bacteria perform a number of necessary functions in the intestinal tract. Some "bad" bacteria cause no problems as long as their numbers remain low but can make you sick if they multiply or travel to other parts of your body.
Defeating Bad Bacteria
Good bacteria help keep bad bacteria from multiplying and causing illness in several ways. They use up nutrients so that bad bacteria don't have access to them. Lactobacilli, found mostly in the small intestine, and Bifidobacteria, found primarily in the large intestine, maintain an acidic environment in the intestines by producing lactic acid, hydrogen peroxide and acetic acid. An acidic environment discourages the growth of bad bacteria. Good bacteria also strengthen (make stronger) the mucosal tissue that lines the inside of the intestines, making it harder for toxins to gain a toehold and take up residence (home).
Digesting Nutrients
Food digestion depends on the actions of good bacteria, which break down complex sugars, proteins and fats so your body can absorb their energy. Lactobacilli, the dominant microorganisms found in the small intestine, break down proteins as well as lactose, which is found in dairy products, and cholesterol for absorption.
Synthesizing Vitamins
Some bacteria also synthesize (make) vitamins. Lactobacillus acidophilus manufactures vitamin K. Lactic acid bacteria produce some B-complex vitamins, while enteric bacteria produce vitamin B-12.
Aiding the Immune System
Good bacteria play a powerful role in supporting the immune system. One type of Lactobacillus, L. caseii, produces bacteriocins, compounds that restrict the growth of harmful bacteria in the small intestine. Good bacteria increase white blood cells called T-cells, which aid in the immune system's response to harmful bacteria. A review of available studies conducted by the Veterans Administration Puget Sound Health Care System and published in the April 2006 issue of "The American Journal of Gastroenterology" found that taking probiotics, which consist of "good" bacteria, can shorten the duration of diarrhea after antibiotic administration and in Clostridium difficile infections.
Bacteria Homework
Directions: Read the article. Then, after reading, follow the activities below. Please answer any questions using complete sentences.
Part One: Key Vocabulary
-Advent: the creation of.
-Strengthen: to make stronger
-Synthesize: to make/build up
Your Key Words
1) Find twonew key vocabulary words in this article and define the word in the space below:
a) ______
b) ______
2) In one sentence, summarize the purpose of the article.
Part Two Directions:For the statements below, identify if the statement is true or false. Make sure to write the sentence out of the text that supports your decision. An example is given below.
Example: Listeria bacteria causes the disease listeriosis.
Answer: True. The article states, “Listeria monocytogenes bacteria cause a disease called listeriosis.”
3) Good bacteria can defeat bad bacteria by using up their nutrients.
4) Good bacteria break down complex food items in our stomachs.
5) The bacteria Lactobacillus acidophilus manufacture the creation of Vitamin C.
6) Good bacteria increase white blood cells called B cells.
Part Three: Anaysis Questions: Answer using complete sentences.
7) Out of the benefits listed in the article, which method do you think is most important for the human body? Why?
Opinion:
8) Why do you think people think all bacteria are bad? Explain!