Module 2 The Endocrine System

Reflect and Connect

Suppose you have a 92 year old grandfather who lives in an extended care facility. He is sharp as a tack, but has Type 2 diabetes mellitus. He is very conscientious about making sure that he injects his insulin regularly. You go to visit him and he tells you about an incident that really scared him. He relates how he had become ill and experienced vomiting and diarrhea all day. He thinks that this was caused by the institutional food! He lost his appetite for eating but injected his insulin normally. A nurse found him unconscious on the floor of his room. Luckily the facility physician diagnosed the cause and helped him. He asks you to help him understand what happened. What would you say? Think about what you have learned in this lesson. Can you suggest what condition may have occurred in your grandfather’s blood because he stopped eating, but continued to inject insulin? Can you predict what the physician did to treat your grandfather? Did your grandfather forget to monitor his blood glucose? Should he have been injecting the insulin if he was not eating? Did he know this? Can you review with your grandfather what the role of insulin that he injects has in his body? You may want to discuss these questions with your instructor to verify your ideas. Then, proceed with the following assessment and submit it to your instructor.

 

Module 2: Lesson 5 Assignment

You can now complete your online assignment 1.2.5

 

As you review this lesson, apply your knowledge to develop hypotheses about:

• the effect the tumors in the islets of the pancreas had on Emily
• the effect to Emily’s blood glucose levels 
• about whether or not Emily became a diabetic
• Technologies and treatments that would be available, and how they would help Emily establish homeostasis.

Going Beyond

A University of Alberta research team has developed a procedure called the Edmonton Protocol that helps people who difficulty managing Type 1 diabetes undergo an islet transplant procedure. Read page 466 in your textbook which is an interview with Dr. Edmond Ryan, Medical Director of the University of Alberta Clinical Islet Transplant Program.

1. Research how islet transplantation in the Edmonton Protocol is performed.
2. Islet transplant patients must wait for the treatment until donated organs become available. Outline three other potential sources of islet cells and outline the issues related with each source.
3. Explain why stem cell research is important to islet cell transplantation

Lesson Summary

Communication of information to and from a command centre in a battle is essential for success. The pancreas is like a command centre which monitors blood glucose. High levels of glucose stimulate the beta cells in the islets of the pancreas to secrete insulin, which increases the passage of glucose into body cells and promotes the conversion of glucose to glycogen in liver and muscle cells, and to fat in the adipose cells. Low glucose levels stimulate the pancreatic alpha cells in the islets to secrete glucagon which promotes the breakdown of glycogen to glucose, and the release of this glucose into the bloodstream.

 

When the communication is disrupted, the battle may be lost. So it is with blood glucose regulation. If the beta cells are destroyed by an autoimmune disease and little or no insulin is produced, consistently high blood glucose levels result in Type 1 diabetes. Left untreated, life-threatening consequences result.

 

Regular glucose monitoring and insulin injections are the only treatment. Insulin cannot be taken in pill form because the digestive system would break it down before it could be absorbed. As a command centre, if the pancreas sends out insulin but the body cells ignore it (called insulin resistance), Type 2 diabetes results. Being very fat (obese) increases the cells inability to respond to insulin. The obvious treatment is to lose weight. Controlling diet and regular exercise can persuade the cells to respond to the insulin. In some cases drugs have to be used.

 

Sometimes the pancreas secretes too much insulin and hypoglycemia occurs. The person becomes anxious, nervous, develops shakiness and has a feeling of weakness. Continued hypoglycemia causes the brain to become disoriented and may progress to unconsciousness and possibly death. If symptoms are recognized quickly, it is easily treated by eating candy or injecting glucagon.

Medical technologies for dealing with diabetes mellitus have progressed from glucose dipsticks to digital glucose monitors, and from syringes to insulin pens to insulin pumps. Hard to manage cases can be treated with islet transplants.

 

Glossary

alpha cells: cells in the islets that secrete glucagon

beta cells: cells in the islets that secrete insulin

diabetes mellitus: a serious chronic disorder that results when the pancreas does not produce enough insulin, insulin receptors, or body cells do not respond to insulin; levels of blood glucose tend to rise sharply (spike) after meals (hyperglycemia) and remain at significantly elevated levels

glucagon: a hormone, secreted by the alpha cells in the islets of the pancreas, which raises blood glucose levels by stimulating liver cells to convert glycogen to glucose; also stimulates fat cells (adipose cells) to convert fat to glucose

hyperglycemia: a condition resulting from high levels of blood glucose; occurs in individuals with diabetes mellitus

hypoglycemia: a condition resulting from low levels of blood glucose; occurs in individuals who secrete excessive amounts of insulin when a tumor develops in the beta cells, or in diabetics who have injected too much insulin

insulin: a hormone, secreted by the beta cells in the islets of the pancreas, which lowers blood glucose levels by promoting the uptake of glucose by most cells of the body, and the synthesis and storage of glycogen in the liver; also stimulates protein and fat synthesis

islets: also called the islets of Langerhans; composed of clusters of alpha and beta cells which secrete glucagon and insulin, respectively, into the blood

pancreas: a gland with dual function; the non-endocrine part secretes digestive enzymes into the intestine through the pancreatic duct, while the endocrine portion called the islets of Langerhans secretes insulin and glucagon into the bloodstream
Type 1 diabetes: also called juvenile diabetes or insulin-dependent diabetes; an autoimmune disorder in which the immune system produces antibodies that attack and destroy the beta cells of the pancreas so that they are unable to produce insulin; usually diagnosed at an early age and the individuals require daily injections of insulin

Type 2 diabetes: also called adult-onset diabetes or insulin-independent diabetes; a disorder that develops slowly over time because the insulin receptors on the body’s cells stop responding to insulin, or because the beta cells of the pancreas produce less and less insulin over time; appears to be related to overweight and obese individuals