the stimulatory and inhibitory effect of adrenaline

1.

during time of stress or activity, adrenaline is secreted into the blood by the adrenal medulla

2.

adrenaline travels in the blood and binds to the adrenergic receptors on the cell membrane of the hepatocytes

3.

the binding activates an enzyme in the cell membrane called adenylyl cyclase

4.

this enzyme catalyses the production of a secondary messenger called cyclic AMP (cAMP) from ATP

5.

cAMP activates a cascade of enzyme controlled reaction which results in the breakdown of glycogen into a glucose (glycogenolysis)

6.

the glucose is released by the liver cells into the blood7

7.

cells make use of the increased glucose conc and the rate of respiration increases