- The levels of glucose, insulin and glucagon were measured in the plasma of 24 healthy adults at intervals over a 5-hour period. After 1 hour at rest the patients ate a large carbohydrate meal. The results are shown.
- Use the data provided to explain how blood glucose is controlled in the body. (6 marks)
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- Outline how in humans, maintenance of temperature is different to the way that glucose is controlled. (3 marks)
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a. Glucose Levels
→ Plasma levels within the first 60 minutes represent the resting glucose levels of the individuals.
→ After the 1 hour mark, the rise in glucose is a result of the absorption of glucose into the bloodstream from the gut after eating the carb rich meal.
Insulin Levels
→ Insulin is a hormone secreted by beta cells in the pancreas. It causes excess glucose in the bloodstream to be taken by the liver and stored as glycogen.
→ This can be seen when the insulin levels directly correlate to the amount of glucose in the body; glucose absorbed in the meal stimulates release of insulin.
→ The reduction in glucose by the insulin then causes insulin to also fall.
Glucagon Levels
→ Glucagon is a hormone secreted by alpha cells in the pancreas. It can almost be seen as the opposite of insulin, and forms the negative feedback loop responsible for controlling blood glucose.
→ It causes glycogen stores in the liver to decompose into glucose and be absorbed by the bloodstream when blood glucose levels drop too low.
→ When glucose levels rise between the 1-2 hour mark, glucagon levels drop significantly, as the build up of glucose from the meal has meant that glycogen stores are not needed.
→ Gradually, as glucose levels drop, glucagon levels will increase as the glucose from the meal is depleted.
b. Differences in temperature vs glucose maintenance
→ Temperature changes are detected by the hypothalamus and sensory neurons, but changes in blood glucose levels (BGL) are detected by the pancreas.
→ Responses are carried out by the nervous system when temperature changes are detected, but carried out by hormones when changes in BGL are detected.
a. Glucose Levels
→ Plasma levels within the first 60 minutes represent the resting glucose levels of the individuals.
→ After the 1 hour mark, the rise in glucose is a result of the absorption of glucose into the bloodstream from the gut after eating the carb rich meal.
Insulin Levels
→ Insulin is a hormone secreted by beta cells in the pancreas. It causes excess glucose in the bloodstream to be taken by the liver and stored as glycogen.
→ This can be seen when the insulin levels directly correlate to the amount of glucose in the body; glucose absorbed in the meal stimulates release of insulin.
→ The reduction in glucose by the insulin then causes insulin to also fall.
Glucagon Levels
→ Glucagon is a hormone secreted by alpha cells in the pancreas. It can almost be seen as the opposite of insulin, and forms the negative feedback loop responsible for controlling blood glucose.
→ It causes glycogen stores in the liver to decompose into glucose and be absorbed by the bloodstream when blood glucose levels drop too low.
→ When glucose levels rise between the 1-2 hour mark, glucagon levels drop significantly, as the build up of glucose from the meal has meant that glycogen stores are not needed.
→ Gradually, as glucose levels drop, glucagon levels will increase as the glucose from the meal is depleted.
b. Differences in temperature vs glucose maintenance:
→ Temperature changes are detected by the hypothalamus and sensory neurons, but changes in blood glucose levels (BGL) are detected by the pancreas.
→ Responses are carried out by the nervous system when temperature changes are detected, but carried out by hormones when changes in BGL are detected.