Read the passage below and answer the questions that follow.
Many years ago, researchers investigated the role of the pancreas by studying canine and rodent models. In one study, the pancreas was surgically removed from a group of healthy mice. These mice quickly developed symptoms of severe diabetes, including a high concentration of glucose in their urine, which attracted insects. This was because their blood glucose levels rose far above the normal renal threshold of 10 mmol/dm3, leading to glucose excreted in urine.
In another study, researchers tied a ligature around the pancreatic duct of rats. This prevented pancreatic juices from reaching the duodenum. While the exocrine cells that secrete digestive enzymes eventually degenerated, these rats did not exhibit glucose in their urine and could still regulate their blood glucose levels.
Later, scientists prepared an active extract from healthy pancreatic tissue by grinding it in a buffered saline solution. When this extract was injected into the diabetic mice, their blood glucose levels decreased significantly.
We now understand that the pancreas houses endocrine cells called the Islets of Langerhans, containing α \alpha\,α and β \beta\,β cells. High blood glucose levels stimulate β \beta\,β cells to release insulin directly into the blood. Insulin travels in the blood to the liver and skeletal muscles, where it stimulates the uptake of glucose and its conversion into glycogen, an insoluble polysaccharide used for storage. Conversely, low blood glucose levels stimulate α \alpha\,α cells to secrete glucagon, which promotes the breakdown of glycogen back into soluble glucose.
Explain what is meant by the term absorption in the digestive system.
Explain why the mice that had their pancreas removed produced urine containing glucose.
Name two pancreatic digestive enzymes that are normally secreted into the pancreatic duct.
Suggest why the rats with a tied pancreatic duct were still able to regulate their blood glucose levels.
The scientists who injected the pancreatic extract into the diabetic mice should have carried out a control experiment. Explain the control experiment they should have conducted.
Name the blood vessel that carries absorbed glucose directly from the small intestine to the liver.
Suggest one property of glycogen that makes it an advantageous storage molecule in cells compared to glucose.
The control of blood glucose level is an example of homeostatic coordination.
Describe the stimulus when blood glucose is high.
Name the receptor that detects this stimulus.
Name an effector organ for this response.
Describe the response of this effector in lowering blood glucose levels.
