How does exercise affect the heart?
Exercise increases the heart rate:
Muscles require more oxygen for aerobic respiration.
That oxygen is supplied by the bloodstream.
The flow of blood is determined by the heart rate
Exercise also increases stroke volume:
Stroke volume is the volume of blood pumped in one heartbeat.
A more powerful contraction in the heart causes more blood to be pumped every ‘stroke’.
How to measure heart rate
Heart rate can be estimated by measuring pulse rate.
The heartbeat will cause the walls of arteries to ‘pulse’ at the same rate.
A pulse is usually taken by holding two fingers to the neck or the wrist
How to measure the change in heart rate after excersise
Take a resting pulse for 1 minute.
Run for 2 minutes at maximum effort.
Take pulse again
Adrenaline
Adrenaline is a hormone that is released during exercise or stress.
Adrenaline is responsible for the ‘fight or flight’ response.
Adrenaline increases both heart rate and stroke volume.
More oxygen is supplied to tissues for respiration.
More energy is released.
Blood is also redirected from other organs.
Blood is diverted from the digestive system during periods of intense exercise.
Cause of coronary heart disease (CHD)
Fatty substances including cholesterol can deposit on the walls of the coronary arteries.
This plaque can cut off the blood supply to the cardiac muscle.
Symptoms of coronary heart disease
Chest pain
Shortness of breath
What can CHD cause
Heart attacks
Where does CHD occur
The coronary arteries in the heart
Diagram for coronary heart desease
Risk factors of CHD (4)
Genetics
Diet
Stress
Smoking
Explanation for genetics as a risk factors of CHD
Many people have a genetic predisposition to CHD
Explanation for diet as a risk factors of CHD
Poor diet can lead to high cholesterol which is a major risk factor for CHD
Explanation for stress as a risk factors of CHD
When stressed blood pressure inceases causing damage to the walls of arteries.
Explanation for smoking as a risk factors of CHD
Nicotine increases blood pressure and increases the likelihood of blood clots.