The factors that influence blood glucose concentration. The role of the liver in glycogenesis and gluconeogenesis. The role of insulin and glucagon in controlling the uptake of glucose by cells and in activating enzymes involved in the interconversion of glucose and glycogen. The effect of adrenaline on glycogen breakdown and synthesis. The second messenger model of adrenaline and glucagon action. Types I and II diabetes and control by insulin and manipulation of the diet.

Types I and II diabetes and control by insulin and manipulation of the diet.

Factors that influence concentration:

• The amount you take in as carbohydrates in food
• The amount broken down from glycogen which is a molecule stored in the liver (glycogenolysis)
• The amount produced by the body from glycerol and amino acids (gluconeogenesis)

The pancreas has pieces of tissue called islets of Langerhans which contain alpha (α) and beta (β) cells, both of which play a role in the control of blood glucose levels.

β cells

Detect when blood glucose is too high and secrete insulin which:

• Bind to glycoprotein receptors of cells which makes them change the shape of their protein channels to let more glucose in (taking it out of the blood)
• Activate enzymes that convert glucose into glycogen (glycogenesis) and fat
• Increase the rate of respiration so more glucose is broken down by cells

α cells

Detect when blood glucose is too low and secrete glucagon which

• Binds to receptors on liver cells causing it to
• activate an enzyme to convert glycogen to glucose (glycogenlysis)
• converts amino acids and glycerol into glucose (gluconeogenesis)

Adrenaline

This also has a role to play in the control of blood glucose. It is produced by the adrenal glands during stress.

It increases blood glucose by:

• Binding to receptors on the liver which
• activates an enzyme that converts glycogen to glucose (glycogenlysis)
• deactivates an enzyme which makes glycogen from glucose.

Second messenger model

• Adrenaline and glucose are first messengers which bind to receptors on the outside of the liver
• This activates an enzyme to produce another messenger on the inside of the liver
• This messenger then activates or deactivates the desired enzymes to control glucose levels

Type 1 diabetes

• Insulin dependent
• Fast and noticible
• The body is unable to produce insulin
• Possibly because the β cells are being attacked by the immune system
• There is no uptake of glucose into cells
• Insulin is injected to control it

Type 2 diabetes

• Insulin independent
• Slow and subtle
• Glycoprotein receptors stop responding to insulin
• Cause by a bad diet
• Controlled by dieting to restrict carbohydrates
• or Drugs to stimulate more insulin to be produced
• or Drugs to slow the rate of absorbtion of glucose from the intestine