While it's common to think of metabolism as nothing more than the number of calories your cells burn each day, metabolism is actually the sum of all chemical reactions that take place in the body. The metabolic reactions that produce energy are dependent upon the cardiovascular system, which delivers oxygen to all your body cells.
Though metabolism doesn't consist solely of the reactions that burn nutrients like carbohydrates, fats and protein, these are perhaps the most widely known of the metabolic reactions. Your metabolism, however, actually includes every chemical reaction that takes place in your body, Drs. Mary Campbell and Shawn Farrell explain in their book "Biochemistry." Some of these reactions burn molecules to produce energy, while others use energy to make larger molecules that the cells use for a variety of purposes, both functional and structural.
Your Cardiovascular System
The cardiovascular system consists of the heart, blood vessels and blood. It's a relatively simple -- though critically important -- body system, in that it operates much like a pump and series of pipes through which water might move. The purpose of the system is to circulate oxygen to your body cells, but also to circulate nutrients. Your blood then returns the waste products -- including carbon dioxide -- of various metabolic reactions to the lungs and to excretory organs, Dr. Laurlaee Sherwood explains in her book "Human Physiology."
Effect of Cardiovascular System On Metabolism
Your cardiovascular system provides your cells with the oxygen and nutrients they need to generate energy and with the building blocks they need to make larger molecules. In this way, the relationship between the cardiovascular system and metabolism is inextricable; you wouldn't be able to get the nutrient molecules from the foods you eat -- or the oxygen from the air you breathe -- to your cells without your heart, blood vessels and blood.
In much the same way, your cardiovascular system is dependent upon metabolic reactions. Your heart muscle needs ATP -- adenosine triphosphate -- to function. ATP is a chemical energy "currency" that you produce when you burn nutrient molecules. The tissues of which your heart and blood vessels are made, and the cells and other components of your blood, are all products of metabolic reactions. Quite literally, your cardiovascular system couldn't exist without the products of metabolism.