TEACHER ANSWER KEY
Answer the following questions about information from this
unit.
1. How would an individual have to alter their eating habits
if a large portion of the stomach was removed?
If a large part of the stomach were removed, an individual would break
down proteins less efficiently since the gastric juice is comprised of
hydrochloric acid (HCl) and enzymes that break down protein. Because proteins are normally
broken down in the stomach, the peptide bonds between the amino acids are made more
accessible to the enzymes. For this reason, an individual may have problems digesting protein,
causing an upset stomach. Also, because the proteins are less digested before entering the
intestines, some of the vital nutrients and materials from the proteins may not be extracted as
easily. This may leave a person wanting/needing to consume more proteins just to get the vital
materials that they provide.
2. A person with anemia has a low red blood cell count. One type of anemia is
pernicious anemia, which occurs when an individual doesn’t have a sufficient
amount of vitamin B12. Why would people who have had either their stomach or
the end of their small intestine removed develop pernicious anemia? Is vitamin
B12 essential in your diet or can your body make it on its own?
Vitamin B12 is acquired from protein and is also produced by bacteria in the small intestine.
Individuals who have had parts of their stomach removed may not adequately break down
proteins (see above), leaving them unable to access adequate amounts of B12 through the
proteins they consume. The bacteria in the small intestine also produce B12, so if the small
intestine is partially removed, this too can impact the levels of B12 in the body. Vitamin B12 is
essential for healthy nerve cells and red blood cells, and is needed to make DNA. Although B12
is produced by bacteria in the lower intestine, the bacteria do not produce enough of it to keep an
individual healthy. Having proteins or B12 fortified foods is important to maintain healthy
levels of B12.
Digestive System: Activity 2
1
TEACHER ANSWER KEY
3. Why do your own fecal bacteria not make you sick?
Describe some ways your body protects you from consuming bacteria.
Your immune system has already been exposed to the bacteria in your
intestine and is ready to kill the bacteria if it enters any other cavity of the
body. However, your immune system has not been exposed to other fecal bacteria so there is no
immunity to it. The acids in your stomach protect you from ingested bacteria. Hand washing
after using the restroom may reduce exposure to fecal and other types of bacteria.
4. Imagine if your liver stopped secreting bile. Describe the consequences by
applying what you have read about the liver and bile.
If your body stopped secreting bile, you would not be able to fully digest fats. Bile aids in
digestion by emulsifying fats, enabling the absorption of fats and of the fat-soluble vitamins (A,
D, E, and K) through the intestinal wall. Since unabsorbed fats tend to coat other foods and
prevent the action of digestive enzymes, adequate fat absorption mediated by bile is necessary
for the complete digestion of food. Also, the bile acts to neutralize the stomach acid in the small
intestine, providing a more optimum environment for the pancreatic enzymes. Without this
neutralizing action, the stomach acid could damage the intestine. The bile is also a route of
excretion for many drugs and metabolites. Cholesterol is excreted almost entirely in the bile, as
are breakdown products of heme, such as bilirubin, which color the bile and are known as the
bile pigments. These products would not be able to leave the body without bile secretion. If the
flow of bile is impeded, digestive disturbances and jaundice may result.
Digestive System: Activity 2
2