Control of blood glucose

Control of blood glucose

1. In humans, diet and exercise are two important lifestyle factors affecting blood glucose concentrations

2. Diet. The glyceamic index (GI) is a system used to rank carboohydrate containing foods based on their overall effect on blood glucose levels. Eating foods with a high GI causes blood glucose concentrations to rise rapidly. Carbohyfrates from foods with a low GI are absorbed into the bloodstream over a relatively long period, helping to maintain stable blood glucose concentrations between meals

3. Exercise; particularly anaerobic exercise, may make high demands on blood glucose. In most circumstances, the increased metabolism resulting form exercise triggers the conversion of glycogen stores in muscle cells and liver cells to glucose, maintaing the blood glucose concentration relatively constant. However, extremely stenous exercise may result in a temporary reduction in blood glucose concentration

4. Hormones; the most important internal factor that affects blood glucose concentration is the interaction of hormones; insulin tends to reduce blood glucose concentration while glucagon and adrenaline tend to increase

5. The role of the liver. It plays a centeral role in metabolism, regulating the concentrations of a wide range of chemicals in the blood including glucose. The liver recieves, via the hepatic portal vein, all the glucose absorbed into the blood through the intesinal wall. The blood glucose concentration leaving the liver, it may be reduced, or it may be increased

   • Glucose can be added to the blood leaving the liver by;
     • Glycogenolysis; 'glycogen splitting' - hydrolysing glycogen to glucose
     • Gluconeogenesis; 'new glucose formation' - converting non-carbohydrate substances such as amino acids and glycerol to glucose
   • Glucose can be removed from the blood by;
     • Glycogenesis; 'glycogen forming' - condensing glucose and storing it as glycogen
     • Converting glucose to fat
     • Using glucose as a fuel for cellular respiration