Cardiovascular and Respiratory Systems

The cardiovascular system includes:

• the heart – a muscle that pumps blood
• blood vessels – the series of tubes that transport blood throughout the body
• blood – the fluid that contains red blood cells which carry oxygen (it also has a role in ridding the body of carbon dioxide and metabolic waste products, temperature regulation and acid base balance. These functions are complex and elaborated on in exercise physiology course work.)

One of the most important tasks of the cardiovascular system is to deliver oxygen to tissues. As we exercise and place an appropriate amount of stress on our cardiovascular system, we experience several adaptations resulting in improved fitness.

• The heart muscle gets stronger and larger, making it a more effective pump. This is why our resting heart rate and heart rate at a given workload will decrease after a period of training. The heart won’t need to pump as often because each time it does, it is pumping a larger volume of blood.
• The number of blood vessels to tissues increases, specifically to skeletal muscles. This allows more oxygen to be delivered to the mitochondria – they are the powerhouse of muscle cells!
• Our blood volume increases, which also allows for more red blood cells (carrying oxygen) to reach more tissues. Blood can also become less viscous, meaning it will flow more easily.