Year 9 Biology

Blood sugar and Diabetes

Prior learningThat sugar is available in the blood as glucose and regulated by the brain, pancreas and the liverKey wordsinsulin, glucagon, liver, pancreas, hypothalamus, negative feedback

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Some hormones affect only one target organ, but most affect more than one.

When the hormone has had the desired effect, further production of the hormone needs to be controlled.

Hormone production is controlled by a process called negative feedback.

The regulation of blood glucose level is an example of negative feedback.

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The level of glucose in the blood decreases, causing the pancreas to stop producing insulin. Insulin produced by the pancreas tells cells to take insulin from the blood and convert it to GLYCOGEN which is stored in the LIVER

blood glucose returns to normal

increased blood glucose insulin

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The level of glucose in the blood increases, causing the pancreas to stop producing glucagon. Glucagon stimulates the liver to convert glycogen back to glucose and release it back in the blood stream.

Negative feedback – low blood glucose

decreased blood glucose

blood glucose returns to normal

glucagon

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1 Look at the grapha Which point, 1 or 2, shows just after a meal was eaten?

Explain your answer.b Which point, 1 or 2, shows when insulin was released

by the pancreas? Explain your answer.c Between which values does blood glucose

concentrationnormally vary?

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When hormones go wrong – diabetes

After a person with diabetes has eaten, their blood glucose level increases. What happens to this glucose?

The absence of insulin means that glucose is not converted to glycogen and stored in the liver, so the blood of a

Lack of insulin production means that the blood glucose level is unregulated and causes the condition known as “sugar diabetes”. Symtoms of diabetes include; glucose in urine, unusual thirst and lack of energy

diabetic contains extra glucose.

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When hormones go wrong – diabetes

Glucose is essential for the body, so why is excess glucose a danger for people with diabetes?

When the glucose is used up, coma and convulsions may occur.

Regular insulin injections and a careful diet can control the condition.

The ability of the kidneys to absorb glucose is also exceeded, so the excess is excreted in urine.

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2 Look at the graph.a Describe the shape of

the curve for the normal person.

b Describe the shape of the curve for the diabetic person.

c Explain the difference between the two curves.

d How much higher has the blood glucose concentration of the diabetic increased beyond the normal range in your answer to question 1c?

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Movie clip - diabetes

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1)Explain why diabetes must be treated. Use a graph to explain your answer (6 marks)

2)Suggest which part of the diet needs most careful control for diabetics. Explain your answer (2 marks)

3)Why does aerobic exercise help control blood glucose concentration? (2 marks)

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Task 2: Create a poster that displays the facts about diabetes