6.4.5 Adrenaline

How Adrenaline Increases Blood Glucose:

1. Adrenaline Binding to Receptors:

• Adrenaline binds to specific receptors on the cell surface membrane of liver cells (hepatocytes).
• This binding causes the receptor to change shape on the inside of the membrane.

2. Activation of Adenyl Cyclase:

• The change in receptor shape activates the enzyme adenyl cyclase.
• Adenyl cyclase converts ATP into cyclic AMP (cAMP), which acts as a secondary messenger.

3. Activation of Protein Kinase Enzymes:

• cAMP activates protein kinase enzymes by changing their shape.
• These enzymes catalyse the conversion of glycogen into glucose (a process called glycogenolysis).

4. Release of Glucose:

• The glucose produced diffuses out of the liver cells and into the bloodstream, increasing blood glucose levels.

Key Points About Adrenaline's Role:

• Works via the secondary messenger system (cAMP).
• Increases blood glucose levels by stimulating glycogenolysis.
• Ensures that glucose is available for respiration during periods of stress or activity.