A Bench to Bedside Primer
Frontiers in Physiology is sponsored by the American Physiological Society (APS) and the
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SEPA, R25 RR025127) at the National Institutes of Health (NIH).
Note: The lesson plans and opinions in this report are those of the authors and do not necessarily reflect the
opinions of any of the supporting institutions or the editors.
Appropriate citation:
Veazey, Tara Bench to Bedside Primer: The Gastrointestinal System and GastroEsophageal Reflux Disease (APS Archive of Teaching Resources Item #5986). [Online].
Bethesda, MD: American Physiological Society, 2011.
http://www.apsarchive.org/my/submit9.cfm?submissionID=5986
Editor’s notes:
This four-page “primer” (a booklet of basic principles) highlights a scientific interest
of the teacher producing it in ONE of three physiology topics: cardiovascular (CV),
renal (REN), or gastrointestinal (GI) physiology. This primer should be readable by
middle to high school students or the general public to help inform them about the
organ system, diseases that affect it, and basic and clinical research being done on it.
This resource can be used as a sample of the primer a teacher wishes to have their
students produce or as an educational tool to explain basic and clinical research.
Website URLs listed in this resource were current as of publication, but may now be
obsolete. If you know of a replacement URL, please suggest it in the resource’s
“Comments” section.
An Errata Page follows this resource.
Disclaimer:
This activity was created by the author and reviewed by the American Physiological
Society. Any interpretations, statements, or conclusions in this publication are those
of the author and do not necessarily represent the views of either the American
Physiological Society or the funding agencies supporting the professional development
program in which the author participated.
Frontiers in Physiology
www.frontiersinphys.org
Permission is granted for workshop/classroom use with appropriate citation
Errata Page
Scientific Accuracy
The author stated that 74% of all Americans have GERD. This number is not accurate.
It is stated that 25 million Americans suffer from GERD. This is not 74%.
The GI system also includes the colon, rectum and anus. The processes are much more
complicated and complex than presented here. Saliva helps to breakdown
carbohydrates via amylases, no chemical digestion of lipid or protein in the mouth.
Once in the stomach food is further broken down via both chemical & mechanical
processes; this is the classical explanation. Once food stuffs enter the duodenum
(small intestine), the chyme undergoes further chemical digestion of carbohydrate,
lipid, and protein. Digesta enters the large intestine where a majority of remaining
water is reabsorbed and fecal matter enters the colon and rectum.
Frontiers in Physiology
www.frontiersinphys.org
Permission is granted for workshop/classroom use with appropriate citation
Gastrointestinal System:
Gastroesophageal Reflux Disease
Facts about the Gastrointestinal System
The Gastrointestinal System, also known as the
digestive system is basically everything that takes place
from the time food enters your mouth until the waste
exits your body. The system includes: the mouth,
esophagus, stomach, liver, pancreas, and both the small
and large intestines. The purpose of the system is
simply to breakdown food for digestion and supplies
your body with the needed nutrients.
The mouth is where digestion first begins.
Inside the mouth your body produces saliva which will
act like a lubricant as well as help break down the food.
Once you have chewed and initially broken down the
food, the food enters into a 10 inch tube called the
esophagus which transports the food into the stomach.
Once in the stomach the food is simply broken down
further for easier absorption.
After exiting the stomach the food then enters
into the incredibly long (22 feet) small intestines. The
majority of digestion takes place inside of the small
intestines, where the nutrients and minerals are
absorbed into the body. Any leftover waste is then
transported into the large intestines. The large
intestine, colon, is approximately 5 feet long and is
simply where waste removal occurs. Water is absorbed
then any leftover waste, stool, is finally transported into
the anal sphincter for removal.
www.clipart.com
References:
Colorado State University: http://www.vivo.colostate.edu/hbooks/pathphys/digestion/basics/index.html
Wiley Publishers: http://media.wiley.com/product_data/excerpt/32/04714422/0471442232.pdf
Facts about
Gastroesophageal Reflux Disease (GERD)
What is it?
GERD is a persistent acid reflux that occurs more than twice a week that can be found in people
of all ages. People often confuse GERD with heartburn, acid reflux or acid indigestion. It is
thought that GERD may be caused when acid comes in contact with the lining of the esophagus
causing burning in the chest or throat. At this time it is unclear on the exact causes of GERD.
Lifestyle Changes to help reduce GERD:
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Stop Smoking
Avoid foods that trigger symptoms
Lose weight
Wear lose fitting clothing
Eat smaller portions, more frequently
Do not eat 3 hours before bed time.
Foods to Avoid:
Long Term Complications:
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Inflammation of
Esophagus
Strictures
Barrett’s esophagus
References
American College of Gastroenterology: http://www.acg.gi.org/patients/gihealth.asp
NIDDK/NIH: http://digestive.niddk.nih.gov/ddiseases/a-z.asp
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Citrus Fruits
Chocolate
Caffeine
Fried Foods
Garlic
Onions
Mint
Spicy Foods
Tomato Based Foods
Basic Research on Gastroesophageal Reflux Disease (GERD)
Gastroesophageal Reflux Disease occurs typically when the esophageal sphincter is not opening or
closing correctly. When this occurs it can often result in acid regurgitation. Acid regurgitation over a
period of time may lead to permanent damage to the lining of the esophagus. GERD may also lead to
ulcers in the esophagus, which could lead to trouble swallowing due to a narrowing in the esophagus.
This condition is commonly called Barrett’s esophagus and can result in cancer in the esophagus [1,2]. It
is assumed that approximately seven-forty percent of all American’s may have Gastroesophageal reflux
disease [3,4]. According to an article found in the American Journal of Physiology GERD may also have
other prolonged effects:
Pathogenesis of GERD is linked to the prolonged contact of acidic gastric contents with the
epithelial luminal surface of the esophagus. The magnitude of mucosal injury in GERD is highly
variable. Mild disease may demonstrate no visible mucosal damage, while more severe
manifestations may present with erosions, ulcerations, stricture formation, and Barrett's
metaplastic transformation, which is associated with the development of adenocarcinoma . The
molecular and cellular mechanisms underlying this differential response to acidic injury in the
esophagus remain largely undefined. Much of the investigation into the mechanisms of mucosal
defense against esophageal acid exposure has focused on damage to tight junctions and loss of
epithelial integrity in response to acid contact [4 ].
The importance of studying gastroesophageal reflux disease is to determine not only the cause of why
so many American’s are affected by this disease, but also what can we do differently to prevent this
disease from happening all together. There are such a large number of Americans affected by GERD’s,
yet there really hasn’t been a way as of yet to prevent this disease from occurring. By studying not only
the disease, but how the esophagus works I do believe there is a way if not to prevent GERD than at
least a way to make it manageable for more Americans.
References:
1.
2.
3.
4.
Liu, Julia and John Saltzman. “Endoscopic Treatment of Gastroesophageal Reflux Disease.” The American College of
Gastroenterology. Accessed July 25, 2011.
“Heartburn, Gastroesophageal Reflux (GER), and Gastroesophageal Reflux Disease (GERD).” National Digestive
Diseases Information Clearinghouse. Accessed July 24, 2011.
Souza, Rhonda, Kumar Krishnan, and Stuart Spechlar. "Acid, Bile, and CDX: The ABC's of
M a k i n g M e t a p l a s i a . " A m e r i c a n J ou r n a l o f P h y s i o l o g y . 2 9 5 . ( 2 0 0 8 ) : G 2 1 1 - G 2 1 8 .
Rafiee, Parvaneh, Victoria Nelson, Sharon Manley, Michael Wellner, and Martin Floer.
"Effect of curcumin on acidic pH-induced expression of IL-6 and IL-8 in human esophageal
e p i t h e l i a l c e l l s ( H E T - 1 A ) : r o l e o f P K C , M A P K s , a n d N F - κ B . " A m e r i c a n J o u r n a l o f P h y s i o l og y .
296.2 (2009): G388-G398.
Call for Participants:
To Help Evaluate the Effect of a Low Carbohydrate Diet on
You might be interested in participating in the following study if you suffer from the following:
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Gastroesophageal Reflux Disease (GERD)
Overweight
Acid Reflux
If you are between the ages of eighteen and thirty and have aBMI between 30 kg/m2 and 45 kg/m2
then you could possibly benefit from this study.
PURPOSE:
BENEFITS:
To determine if a low
carbohydrate (sugar) diet will
help control the symptoms of
associated with GERD in
people who are overweight.
Possible benefits of this diet
could include: weight loss,
loss of heartburn, and less
belching.
Anyone who suffers from Gastroesophageal Reflux Disease needs to realize that without a possible
change in diet or medication this disease could be something that last a lifetime. We believe that by
lowering the amount of carbohydrates in your diet your can greatly reduce the amount of suffering or
possibly eliminate the symptoms associated with GERD’s.
For more information feel free to visit the following website:
http://apsed.blackboard.com/webapps/portal/frameset.jsp?tabGroup=courses&url=%2Fwebapps%2Fbl
ackboard%2Fcontent%2FcontentWrapper.jsp%3Fcontent_id%3D_176938_1%26displayName%3DLinked
%2BFile%26course_id%3D_4569_1%26navItem%3Dcontent%26attachment%3Dtrue%26href%3Dhttp%2
53A%252F%252Fwww.clinicaltrials.gov%252F