Answer:
Step-by-step explanation:
One
The heart is like a functioning pump. It moves the blood around the body.
The red blood cells carry oxygen which is delivered to the vital organs of the body. Muscles need oxygen to function properly.
The lungs are like a giant sieve. They separate the oxygen and carbon dioxide.
Two
One of the things the body does is increase your heart rate while exercising. That means that the body receives more oxygen from the seive action of the lungs. In other words, your heart rate increases and red cell blood flow consequently increases.
Three
Interesting application. The heart rate will have to increase to get the same amount of oxygen as the heart rate would be at lower altitutes. There is less oxygen in the thin air in Denver Colorado than say Los Angeles California.