1. Adrenaline and glucagon can bind to specific receptors on the cell-surface membrane of liver cells
2. This changes the conformation of the receptor protein
3. This activates G proteins, which in turn activate adenylyl cyclase
4. This leads to the production of the second messenger cyclic AMP (cAMP)
5. This activates kinase proteins causing an enzyme cascade
6. Phosphorylase kinase enzymes are activated by adding phosphate groups to them
7. Eventually, the cascade triggers the formation of more glucose in liver cells
8. Glucose can then diffuse out of cells into the blood, increasing blood glucose concentration

1. The high blood glucose concentration is detected by β cells in the islets of Langerhans
2. This causes more insulin to be secreted from β cells into the blood
3. Insulin increases the permeability of muscle and fat cells to glucose as more GLUT4 proteins are added into their cell-surface membranes
4. Insulin leads to more glucose being removed from the blood and converted into storage molecules
5. This reduces the blood glucose concentration

1. α cells in the islets of Langerhans - produce glucagon
2. β cells in the islets of Langerhans - produce insulin

1. Glucose is needed for respiration
2. If blood glucose is too low or high it can cause osmotic problems in cells and even cell death

The liver carries out the following to increase or decrease blood glucose concentration:

1. Glycogenesis - the conversion of glucose into glycogen when blood glucose concentration is high
2. Glycogenolysis - the breakdown of glycogen to glucose when blood glucose concentration is low
3. Gluconeogenesis - the production of glucose from sources other than carbohydrates like fats and amino acids

Insulin lowers blood glucose concentration when it is too high by:

1. Increasing the rate of glucose absorption into cells, especially muscle cells
2. Increasing the rate of respiration
3. Promoting glycogenesis
4. Activating enzymes that convert glucose to glycogen and fat
5. Decreasing gluconeogenesis
6. Inhibiting the secretion of glucagon from α cells via negative feedback

Glucagon increases blood glucose concentration when it is too low by:

1. Activating enzymes in liver cells that break down glycogen to glucose (glycogenolysis)
2. Activating enzymes in liver cells that promote gluconeogenesis
3. Inhibiting the secretion of insulin from β cells via negative feedback