Cambridge O Level Biology · Syllabus 5090 · Coordination and Control
Blood Glucose Concentration
What is Blood Glucose Concentration?
The concentration of glucose dissolved in the blood plasma. It is controlled by negative feedback: the pancreas detects a change and releases insulin when it is too high or glucagon when it is too low, and the liver acts as the main effector by converting glucose to glycogen or glycogen back to glucose.
This definition is part of the Coordination and Control chapter in Cambridge O Level Biology.
Questions students ask about Blood Glucose Concentration
What does adrenaline do?
Adrenaline is secreted by the adrenal glands in demanding situations such as fear or vigorous activity. It increases the heart rate and increases the blood glucose concentration, so that more glucose and more oxygen are delivered to the muscles and they can respire faster. Adrenaline does not itself release energy; respiration does.
What does insulin do?
Insulin is released by the pancreas when the blood glucose concentration rises above the set point. It causes body cells to take up more glucose from the blood, and causes the liver to convert glucose into glycogen for storage, so the blood glucose concentration falls back towards the set point.
What does glucagon do?
Glucagon is released by the pancreas when the blood glucose concentration falls below the set point. It causes the liver to convert stored glycogen into glucose and release that glucose into the blood, so the blood glucose concentration rises back towards the set point.
What is Type 1 diabetes and how is it treated?
In Type 1 diabetes the pancreas does not produce enough insulin. The blood glucose concentration therefore becomes abnormally high, and glucose appears in the urine. It is treated by the administration of insulin, under professional medical guidance. Insulin replaces the missing hormone so that blood glucose can be controlled; it does not cure the condition, and the condition is not caused by eating sugar.