The circulatory system consists of the heart and blood and the vessels that transport this blood as well as the hormones and nervous system that affect the flow of the blood. Another huge part of this system is the transport of oxygen into the blood and the transport of carbon dioxide out of the blood, something called respiration and involving the lungs.
Oxygen and glucose are key ingredients in the giving power of the cell that allows it to carry out all of the metabolic processes that it carries out to maintain life. So in an indirect way the digestive system is a part of the circulatory system by providing the glucose ingredient. However the body, especially in populations like ours that have an overabundance of “fuel” in our diet, store energy and thus this is not as critical as oxygen to the life of an organism.
Blood is a specialized transporter of oxygen and carbon dioxide and the flow of blood is essential in maintaining the proper gradients of these gases in order for the proper exchanges to take place. Depending on the tissue the amount of time that it can function without a fresh supply of oxygen without irreversible damage is seconds (for nervous tissue) to minutes and even hours for tissues that are more able to carry out anaerobic respiration.
The two most important injuries caused by circulatory system compromise and lack of oxygen are heart attacks or myocardial infarctions and strokes or cerebral vascular accidents. Much has been done to decrease the time from initial symptom to life preserving attention at a fully equipped hospital and this has resulted in dramatic improvements in mortality and morbidity from these injuries.
To learn more about the circulatory system and how you can recognize early signs of compromise and save your or your loved one’s life check out all of the great information on the web from associations like the AMA, and the ACA, and the ANA.