1. Hormonal Control Mechanism

2. Adrenalin & Noradrenalin: Stress hormones released by adrenal glands
Adrenalin & Noradrenalin: Stress hormones released by adrenal glands. Stimulate heart.
Caused by exercise.
Adrenalin stimulates the SA node.
Therefore heart rate increases.

3. Prior to exercise there is an anticipatory rise, where adrenalin is released and raises the heartbeat before exercise, stimulating the heart before you start.
I have an anticipatory rise. Adrenalin has been released to my SA node and I haven’t even started. I’m on a bike.

4. How does the heartbeat rise?
The adrenalin stimulates the SA node in the right atrium.
More electrical impulses are sent out therefore increasing the heart rate.

5. This stress induced adrenalin causes:
Stimulation of the SA node; speed and force of contraction increases.
Blood pressure increase (blood vessels constrict)
Increase in blood glucose.