If the circulatory system were a car, the heart would be the engine. The heart's ability to speed up and slow down the blood flow of the circulatory system is analogous to the manner in which an accelerator and brake can alter gasoline flow through a vehicle. The heart and circulatory system work together to provide the body with nutrient-rich blood, which it relies on for survival.
Every cell in the body needs nutrients to survive. These nutrients reach the cells through blood, which is moved by the circulatory system. It is therefore obvious that a properly functioning circulatory system is necessary for survival. Here's how it works: The heart's contraction forces the ejection of more blood into the system, causing all other blood to slowly move through the tubes that make up the vascular aspects of the circulatory system.
The heart and circulatory system are mechanically linked in this fashion. As the heart beats and beats, it moves blood throughout the body in a systematic function. Just as a car may need more gas if it wants to move faster, the body sometimes needs extra circulation in times of excessive demand. One example of this could be physical exercise.
When the body needs more blood flow to support a higher-than-usual nutritional demand, it relies on the heart and circulatory system to meet this need. The body's sensory mechanism, the nervous system, picks up on this need and immediately calls on the heart to increase frequency and intensity for greater circulation. The heart responds, beating harder and faster until the need is met.
If a car swerves in front of a vehicle on the highway, the vehicle better slow down to avoid an accident. Sometimes, the heart and circulatory system need to slow blood circulation down to prevent physical overhaul. The nervous system is also responsible for sensing this need and putting the heart and circulatory system into action. The heart can beat slower and less intensely to meet this need, and the vessels of the circulatory system also have the ability to change circumference as needed to help accommodate any necessary changes.
The heart and circulatory system are complexly intertwined with the other systems of the body in a manner that helps the body survive efficiently and effectively. The change in need of blood flow is constant; therefore, the perpetual flexibility of the heart and circulatory system is of the utmost importance. In the car that is the body, the engine-like properties of the heart allow for the gasoline-like blood to reach the most distant locations, where it's needed for survival.
