The amount of glucose, or sugar, in the blood must be kept within certain levels. This is the second of two GCSE Biology quizzes looking at how the body controls blood sugar levels with hormones, and it concentrates on how insulin is used to lower the amount of glucose in the blood.
Glucose is the fuel that powers our bodies. During aerobic respiration, glucose is converted to carbon dioxide and water to release energy in cells. If a cell is short of oxygen, anaerobic respiration takes place which releases much less energy from the glucose and produces lactic acid. The level of glucose in the blood can also effect the movement of water into and out of cells by the process of osmosis. This all means that the concentration of glucose in our bodies is extremely important and needs to be carefully regulated in order to keep the concentration within a narrow range of figures.
After eating foods containing carbohydrates, the carbohydrates are broken down to glucose during digestion. The glucose molecules are absorbed through the wall of the small intestine and enter the bloodstream. This means that the glucose concentration in the blood will be a lot higher than it was before eating. Insulin is a hormone released from the pancreas and it controls blood glucose levels after a meal. When the glucose level in the blood is too high, this is detected as the blood passes through the pancreas. The pancreas then secretes insulin into the bloodstream. The insulin stimulates cells in the liver to convert glucose into the substance glycogen, lowering the concentration of glucose in the blood. Glycogen is then stored and can be converted back into glucose later if the level falls too low.
Type 1 diabetes is a condition where the pancreas does not produce insulin or the body is unresponsive to it. Usually, diabetics have to control their blood glucose levels by diet and exercise together with injections of insulin. Diabetics use a small testing kit to take a sample of blood several times each day. They use this sample in a blood glucose meter to find their blood glucose level and can then work out how much insulin they need. Some diabetics wear an insulin pump which supplies the hormone at a low level continuously. This can be altered to increase or decrease the supply at certain times such as after a meal or during exercise.
Have a go at this quiz to see if you understand how the body controls blood sugar levels with insulin.