3.1: What is the cardiovascular and respiratory system?
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Imagine for a moment climbing to the top of Mt. Everest, a challenging feat very few have accomplished. In the process, you gradually ascend from base camp, which sits at about 17,500 feet above sea level, to the peak at over 29,000 feet. At this elevation, the pressure of oxygen is so low, you struggle to take in a satisfying breath. Although you strive to breathe deeply, you are unable to get enough air. Your heart rate increases and you might even develop nausea and a headache. Unless your body has a chance to acclimate itself to higher elevations or you gain access to supplemental oxygen, your symptoms will persist or worsen.
These are the sensations many people with cardiovascular or respiratory illnesses, such as asthma, chronic bronchitis, or mild cardiovascular disease, experience on a daily basis. Climbing up a flight of steps may leave them gasping for air, as would walking briskly or even breathing in cold air. Regardless of the cause, being unable to take in sufficient air can create a sense of panic and cause serious physical discomfort. The goal of this short narrative is to engender an appreciation for the simple act of breathing and the ensuing satisfaction that comes with each life-sustaining breath. For most people, unless they engage in strenuous physical activity, such as jogging or climbing a flight of stairs, their cardiovascular and respiratory system (heart, blood vessels, and lungs) operates efficiently enough to go unnoticed. However, does that mean their cardiorespiratory (CR) system is functioning at optimal capacity, or could it be operating at a minimum level and experiencing problems that go undetected? This chapter defines cardiorespiratory fitness, examines the benefits of a healthy CR system, and explores how to effectively assess and improve the CR system.