7.4

Question 0

It is important that blood glucose levels are kept relatively constant because glucose is the most important:

Answer 0

Respiratory substrate in humans

Question 1

In a healthy human, blood glucose levels are normally kept at about

Answer 1

90mg per 100cm3 of blood

Question 2

If blood glucose level changes significantly this will change the

Answer 2

Water potential of the blood - cells will gain or lose too much water through osmosis

Question 3

The receptors that monitor blood glucose levels are found in the

Answer 3

islets of Langerhans in the pancreas

Question 4

2 main kinds of cells in the islets of Langerhans:

Answer 4

α

β

Question 5

α cells secret the hormone

Answer 5

Glucagon

Question 6

β cells secrete

Answer 6

the hormone insulin

Question 7

Blood glucose levels rise when a meal containing carbohydrates is eaten and glucose is absorbed into the

Answer 7

Blood

Question 8

The rise in glucose is detected by the β cells in the islets of Langerhans.

Insulin travels in the blood and fits into specific receptors in the cell membranes of

Answer 8

Liver and muscle cells

Question 9

Insulin release and blocking of receptors on cell membranes lowers blood glucose level in 4 ways:

Answer 9

• insulin stimulates the uptake of glucose by all respiring cells in the body (especially in liver and muscle cells). In these cells insulin causes glucose channels in plasma membranes to open, allowing more glucose to enter
• insulin stimulates an increase in respiration rate so more glucose is respites
• insulin activates enzymes inside liver and muscle cells, increasing the rate at which glucose is converted into glycogen. (GLYCOGENESIS)
• insulin activates other enzymes which convert glucose into fatty acids. These are converted into fats which are deposited in adipose tissue

Question 10

Insulin is secreted until the blood glucose level returns to

Answer 10

Normal

Question 11

Blood glucose levels can fall when a person has

Answer 11

-not eaten a meal for some time, especially if they have been very active

Question 12

Fall in blood glucose level is detected by the

Answer 12

α cells - secrete hormone glucagon

Question 13

(LBGL) glucagon, like insulin, binds to specific receptor proteins in plasma membranes. This activates enzymes that concert glycogen back to glucose. This process is called

Answer 13

Glucogenolysis

Question 14

(LBGL) glucagon also stimulates the conversion of amino acids to glucose which results in more

Answer 14

Glucose being secreted into the blood

Question 15

To increase blood glucose level:

Answer 15

• Conversion of glycogen to glucose

- Conversion of amino acids to glucose

Question 16

To decrease blood glucose level:

Answer 16

• Increased cellular respiration
• Conversion of glucose to glycogen
• Conversion of glucose to fat
• Absorption of glucose into cells

Question 17

The control of blood glucose is an example of negative feedback because a rise or fall in blood glucose level triggers corrective mechanisms that return the blood glucose level back to the

Answer 17

Normal level