Read the passage below. Use the information in the passage and your own knowledge
to answer the questions that follow.
Glucose control
Many years ago some scientists wanted to find out more about the role of
the pancreas in digestion. They used surgery to remove the pancreas from
dogs to see what would happen. During this investigation a laboratory
assistant noticed that flies collected around the dogs’ urine. This urine was
5 later found to contain large amounts of glucose. Urine from dogs with a
pancreas does not contain glucose.
Another scientist used string to tie a knot around the pancreatic duct of
rabbits, which closed the duct. This meant that no pancreatic enzymes could
reach the small intestine. It was noticed that when this was done, the cells in
10 the pancreas that made enzymes died, but no glucose appeared in the rabbit
urine.
Other scientists made pancreas extract by crushing up a pancreas in water.
They injected this extract into dogs that had their pancreas removed. They
found that the blood glucose level in these dogs was much reduced.
1 5 These investigations and observations suggest that the pancreas has two
different functions. Some of the cells produce enzymes needed for digestion.
Other parts of the pancreas are not involved in digestion but are important
in controlling blood glucose levels.
We now know that pancreas extract contains two hormones involved with
20 the regulation of blood glucose levels – insulin and glucagon. High blood
glucose levels are detected by the pancreas. This stimulates the pancreas
to release insulin. The role of insulin is to lower blood glucose levels. The
insulin is released from specialised cells directly into the blood. The insulin
travels in the blood to target cells that are in the liver and in large muscles.
25 Insulin causes these cells to absorb glucose and use it to make an insoluble
storage carbohydrate called glycogen.
The second hormone called glucagon is released by different cells in the
pancreas when the blood glucose level falls too low. Glucagon causes liver
and muscle cells to change glycogen into soluble glucose.
Explain what is meant by the term digestion (line 2).
(2)
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