blood glucose and diabetes

Question 1

Glucoregulation

Answer 1

Controling blood glucose levels

Question 2

Where are the a-cells and ß-cell located?

Answer 2

Islets of Langerhans

Question 3

What happens when blood glucose levels rise? [3]

Answer 3

• A rise in blood sugar is detected by the pancreas (Islets of Langerhans)
• This causes the pancreas (Islets of Langerhans) to release insulin
• Insulin stimulates the conversion of glucose to glycogen in the liver

Question 4

What happens when blood glucose levels fall? [3]

Answer 4

• A fall in blood sugar is detected by the pancreas (Islets of Langerhans)
• This causes the pancreas (Islets of Langerhans) to release glucagon
• Glucagon stimulates conversion glycogen to glucose in the liver

Question 5

What causes an increase in blood glucose concentration? [3]

Answer 5

• Ingesting Food (dissolved glucose & digestion of polysaccharides)
• Breakdown of stored polysaccharide (glycogen to glucose)
• Formation of glucose (fat to glucose & amino acids to glucose)

Question 6

What causes a decrease in blood glucose concentration? [2]

Answer 6

• Respiration (glucose to energy)
• Storage of glycogen (glucose to glycogen)

Question 7

Pancreas [4]

Answer 7

• The pancreas acts as a receptor as it detects the concentration of glucose in the blood
• It also acts as an effector, as it releases the hormones insulin and glucagon
• The Islets of Langerhans in the Pancreas produce the hormones insulin and glucagon
• The α-cells produce glucagon, the β-cells produce insulin
  (Both types of cell are the receptors, detecting the change in glucose levels)

Question 8

How does an increase in blood glucose levels result in Glycogenesis? [4]

Answer 8

• The stimulus of a rise in blood glucose concentration is detected by receptor β-cells in the pancreas
• Stimulating β-cells to release insulin into the blood
• The response being target cells removing glucose from the blood and converting it to glycogen
• Blood glucose concentration decreases

Question 9

Insulin Target Cells

Answer 9

The target receptors for insulin are throughout the body cells, but in particular are present on liver, muscle and adipose (fat) tissue.

They are not present in Red Blood Cells

Question 10

The Effects of Insulin [3]

Answer 10

• Causes glucose carrier proteins to move from the cytoplasm to the cell membrane, allowing more glucose to be absorbed into the cell
• Altering tertiary structure of glucose carrier proteins to allow greater uptake
• To stimulate enzymes in the liver which convert glucose into glycogen (GLYCOGENESIS)

Question 11

How does a decrease in blood glucose levels result in Glycogenolysis? [4]

Answer 11

• The stimulus of a decrease in blood glucose concentration is detected by receptor α-cells
• Stimulating α-cells to release glucagon into the blood
• The response being target cells converting glycogen back into glucose and releasing it into the blood
• Blood glucose concentration increases

Question 12

The Effect of Glucagon

Answer 12

• Stimulates enzymes in the liver to convert glycogen into glucose (GLYCOGENOLYSIS)
• Converts amino acids, glycerol and fats into glucose (GLUCONEOGENESIS)

Question 13

The Role of Adrenaline

Answer 13

Adrenaline also works to release glucose, in a second messenger model

Question 14

Adrenaline Action [8]

Answer 14

• Adrenaline is the first messenger
• It attaches to a protein receptor in the liver cell membrane
• This protein receptor has an inactive enzyme, adenyl cyclase attached on the internal side of the membrane
• Attachment of adrenaline causes the membrane protein shape to change and the enzyme becomes active
• Activated adenyl cyclase catalyses the conversion of ATP to cyclic AMP (cAMP)
• cAMP is the second messenger
• cAMP activates another enzyme, protein kinase
• This activated enzyme converts glycogen into glucose

Question 15

Gluconeogenesis

Answer 15

Production of glucose from sources other than carbohydrates
(e.g. amino acids, glycerol, fats)

Question 16

Glycogenolysis

Answer 16

Breakdown of glycogen into glucose

Question 17

Glycogenesis

Answer 17

Forming glycogen from glucose

Question 18

What is diabetes?

Answer 18

Diabetes is a condition in which blood sugar levels are not controlled properly

Question 19

What can diabetes result in?

Answer 19

Can result in hyperglycaemia (blood glucose too
high) or hypoglycaemia (blood glucose too low).

Question 20

Hyperglycaemia

Answer 20

= an increase in blood glucose levels
Symptoms = nausea, tiredness, stomach pain, unconsciousness, nerve damage.

Question 21

Hypoglycaemia

Answer 21

= a decrease in blood glucose levels.
Symptoms = shaking, sweating, blurring of vision, unconsciousness

Question 22

Give 6 signs of diabetes

Answer 22

• High blood glucose levels
• Needing to urinate very frequently
• Weight loss
• Blurred vision
• Glucose in urine
• Tiredness

Question 23

Type I Diabetes (insulin-dependent or early-onset) [4]

Answer 23

• Usually occurs in people under the age of 20
• Beta cells are damaged by the immune system (autoimmune disease) and so no insulin can be released
• Need to take daily insulin injections
• Be careful with their diet (not too many sugars) and exercise

Question 24

Type II Diabetes (Insulin Independent)

Answer 24

Occurs in older people (about 40 years old) yet an increasing number of adolescents who are overweight or obese are being diagnosed

Question 25

What can type II diabetes be due to? [2]

Answer 25

Can be due to:
- Insulin glycoprotein receptors become unresponsive
- Pancreas reduces insulin production

Question 26

Type II Diabetes Treatment [4]

Answer 26

• Carefully managed exercise
• Carefully managed diet (carbohydrates - slow releasing energy)
• Lose weight
• Medication - to inhibit breakdown of glycogen, make cells more responsive to insulin