Biology - 9201 OxfordAQA

Control Of Blood Glucose

Overview

Drink a glass of sweetened orange juice and, for a few minutes, a large quantity of sugar pours out of your small intestine and into your bloodstream. Two hours later a blood test would struggle to prove you had drunk anything at all. Something worked very hard, very quietly, to put that number back where it started, and it did so without you noticing or deciding anything.

This lesson is about that something: a small organ tucked behind the stomach that tastes the blood flowing past it and answers with one of two hormones. You will learn what insulin does, what glucagon does, why the body needs both rather than one, and where the glucose actually goes when it leaves the blood. You will then look at what happens when that system stops working properly, in the two forms of diabetes named on the specification, and you will practise reading the blood glucose graphs that OxfordAQA papers keep coming back to.

Objectives

  1. The blood glucose concentration is monitored and controlled by the pancreas. Much of the glucose is stored as glycogen in the liver and muscles. When these stores are full, excess glucose is stored as lipid.
  2. If blood glucose levels are too high, the pancreas produces the hormone insulin, which allows the glucose to move from the blood into the cells.
  3. When blood glucose levels fall, the pancreas produces a second hormone, glucagon. This causes glycogen to be converted into glucose and released into the blood.
  4. In Type 1 diabetes a person’s blood glucose level may be too high because the pancreas does not produce enough insulin. Type 1 diabetes may be controlled by careful diet, exercise, and by injecting insulin.
  5. Type 2 diabetes develops when the body does not respond to its own insulin. Obesity is a significant factor in the development of Type 2 diabetes. Type 2 diabetes can be controlled by careful diet, exercise and by drugs that help the cells to respond to insulin.

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Lesson Note

Glucose in the blood of a healthy person sits inside a narrow band. An OxfordAQA paper quotes the acceptable range before a meal as 4.0 to 7.2 mmol per dm3, and even after a heavy plate of rice the figure comes back down towards the lower end within roughly two hours. That stability is strange when you think about what it is up against: meals arrive at unpredictable times and in unpredictable sizes, while your brain and muscles withdraw glucose from the blood every second of the day and night, including the eight hours you spend asleep and eating nothing. Supply is lumpy and demand is continuous, yet the concentration barely shifts.

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Lesson Evaluation

Congratulations on completing the lesson on Control Of Blood Glucose. Now that youve explored the key concepts and ideas, its time to put your knowledge to the test. This section offers a variety of practice questions designed to reinforce your understanding and help you gauge your grasp of the material.

You will encounter a mix of question types, including multiple-choice questions, short answer questions, and essay questions. Each question is thoughtfully crafted to assess different aspects of your knowledge and critical thinking skills.

Use this evaluation section as an opportunity to reinforce your understanding of the topic and to identify any areas where you may need additional study. Don't be discouraged by any challenges you encounter; instead, view them as opportunities for growth and improvement.

  1. Which organ monitors the concentration of glucose in the blood? A. The liver B. The pancreas C. The kidney D. The small intestine Answer: B
  2. Blood glucose concentration has fallen below normal. Which hormone is released, and what does it cause? A. Insulin, causing glucose to be stored as glycogen B. Insulin, causing glycogen to be converted into glucose C. Glucagon, causing glucose to be stored as glycogen D. Glucagon, causing glycogen to be converted into glucose Answer: D
  3. Where is excess glucose stored once the glycogen stores in the liver and muscles are full? A. As lipid B. As protein C. As extra glycogen in the pancreas D. As starch Answer: A
  4. Which statement describes Type 2 diabetes? A. The pancreas produces too much insulin B. The body does not respond to its own insulin C. The liver cannot store glycogen D. The pancreas produces no glucagon Answer: B
  5. A man's blood glucose concentration rises from 5.0 to 8.0 mmol per dm3 after a meal. What is the percentage increase? A. 37.5% B. 50% C. 60% D. 160% Answer: C

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