L2 - Heart Rate

objectives

• Explain how the heart rate changes during exercise and under the influence of adrenaline

Changing your Heart Rate

• The natural rhythm (myogenic) of the heart can be changed by both the nervous system and hormones.
• Adjustments can be made to accommodate for different levels of activity.
• Heart rate can decrease when we rest, relax or use drugs
• Heart rate can increase when we Exercise, use drugs, are under stress, excitement or fear

Hormonal Control of Heart Rate

Adrenaline is the ‘fight or flight’ hormone that initiates fast changes in a body preparing it for sudden action. It is a defense mechanism.

Adrenaline is produced by the adrenal glands (located on the kidneys) in certain situations (excitement, fear, stress).

Among other effects, when adrenaline is released it increases the heart rate. This supplies our muscles for aerobic respiration in order to release energy to allow us to run away or fight. (The “flight or fight” response.)

Adrenaline is also known as epinephrine.