DP Biology: A miracle cure for ulcers

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A miracle cure for ulcers

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  • Option D - Human physiology Activities for learning/
  • A miracle cure for ulcers

In this activity students learn about how stomach acid prevents the growth of all bacteria except one. Helicobacter pylori is a sneaky spiral pathogen which uses the enzyme urease to make ammonia and bicarbonate to neutralize stomach acid, to give you bad breath and gastric ulcers. The discovery of this bacteria caused a paradigm shift in medical thinking and is a great illustration of the nature of science. It is also a good reinforcement of the control of gastric juice.

Lesson Description

Guiding Questions

  • How does the stomach protect itself from the hydrochloric acid and protein digesting enzymes it contains?
     
  • What could happen if a gunshot wound or a bacteria like H. pylori damaged the stomach lining?

Activity 1 - Digestive juices and protection of the stomach lining

Ulcers are holes in the protective mucous layer of the stomach or duodenum. Stress, alcohol and poor diet are thought to be the cause. Doctors and IB students learn about the mechanisms of both stomach acid production and the way our intestines make mucus to protect epithelial cells.

Watch the short video clips and answer the questions.

This short video   Dr William Beaumont explains simply how William Beaumont discovered the acidity of the stomach and the speed of digestion.

Beaumont observed the activity of the stomach and its gastric secretions in the 1830's.

1. How is this an example of serendipity?

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This clip of public science shows how food looks just after it arrives in the stomach.   Inside a stomach - using an endoscope

 

2. As well as the churning of the stomach what does the endoscope show?

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This short explanation   Armando Hasudungan stomach secretions gives details of the contents of the gastric juice and the cells which produce it.   (Stop watching at 5:30 - the small intestines)

3.  What are the correct functions of the Chief cells and the Parietal cells?

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A short clip explaining where mucus is made and describing the way production of HCl is promoted.  Focus on the

  How hydrochloric acid secretion is regulated

4. What is the important role of epithelial cells mentioned at the beginning?

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complete answers to these questions and the following questions on the  Questions on the gastric juice videos

Activity 2 - Curiosity driven experiments & self-experimentation prove that Helicobacter pylori infection causes stomach ulcers.

As recently as 1980 many people were walking round with a time bomb ticking in their stomach.

Gastric ulcers progressively damaged the mucosa lining the stomach

These ulcers cause periods of great pain, and may lead to stomach cancer in later years.

Medical treatments reduced the acid produced by the stomach and doctors focused on the mechanisms of stomach acid production.

In 1984 experimental evidence finally convinced the medical profession that these ulcers were caused by a spiral bacterium, H.pylori.

Watch the two short clips to hear from the doctors themselves.

Curiosity and winning the nobel prize.

  Short interview with Barry Marshall and Robin Warren

An excellent introduction to Marshll and Warren's work on H.pylori

  Finding a cure for stomach ulcers - Interview with Professor Barry Marshall


Imagine that you are Dr Warren or Dr Marshall.  analyse the biopsy images and the experiment data in  Endoscope biopsy student worksheet​. Does the data support the claim that H. pylori causes ulcers?

Activity 3 - Villi, Pancreatic juice, Fibre and digestive function

This is a short summary activity to cover the last few details of this extra digestive system topic

  

This Hollywood news story shows a new type of pizza which could cause particularly bad constipation.

Look at the slides and answer the following questions.

Questions

What is the claim makes in the news headline?

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What is the relationship between transit of food though the intestines and the speed of peristalsis?

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Pizza, and chocolate are low in dietary fibre, what is the role of fibre, and what is its effect on the rate of transit of materials through the intestines?

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Discuss whether the data in the velocity of bowel movements  graph supports the hypothesis that eating chocolate pizza causes slow bowel movements and constipation?

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Materials not absorbed by the intestines are egested as stools. Fibre is cellulose and difficult to digest.  How could this explain why a vegetarian diet might have a larger mass of egested stools than other diets.

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Things to include somewhere.

  1. Cholera -  how it damages epithelial cells in the small intestines and causes dehydration through leakage of water from the body into the colon and the faeces.

Teacher's notes

Beaumont's book, Experiments and observations on the gastric juice and digestion. makes interesting reading - linked to serendipity and discoveries in science — as he conducted an ingenious experiment to observe the process of digestion in an open wound caused by gunshot.

This is a nice case study from National Center for case study teaching in science

More information about Helicobacter -

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Model answers for both of the worksheets can be found here. Gastric secretions - model answers

These questions aim to get students thinking and making links, they are quite challenging and students may need guidance.