STPM Biology - chapter 11: Revision essay question 4

4. What are the hormones produced by the pancreas that regulate blood glucose?  How do they work together to regulate blood glucose levels?  How would consuming large quantities of starchy foods, such as pasta, benefit a person prior to running a marathon?

Answer 

The pancreas makes insulin, which is produced in higher concentrations as blood glucose concentration increases, such as after consuming a meal rich in carbohydrates.  This causes cells of the liver, muscle cells, and fat cells to absorb glucose.  As blood glucose levels fall, the pancreas produces less insulin.  The pancreas also makes glucagon, which is produced in higher concentrations when blood glucose levels drop too low.  Glucagon causes the conversion of glycogen stored in the liver into glucose, which enters the circulatory system and raises blood glucose concentrations back to normal range.   As blood glucose levels return to a normal range, the pancreas reduces its production of glucagon.

A common practice prior to running a marathon or participating in other long endurance sports, is to consume a large quantity of foods rich in starch that increase blood glucose levels.  In response, the pancreas produces more insulin, which causes liver cells to absorb glucose and convert it to glycogen, which is stored in the liver.  During a high endurance activity, such as a marathon, glycogen is converted back to glucose, which raises blood glucose levels back to a normal level and allows the person to continue their activity.