The cardiovascular, or circulatory, system is a closed elastic circuit consisting of the heart, blood vessels (arteries, capillaries and veins) and the blood. The primary function is to pump oxygenated blood to the tissues throughout the body and reabsorb waste carbon dioxide for its removal. This function is performed by the use of pulmonary and systemic circulation.
The pulmonary circulation controls the blood that flows between the heart and lungs for gaseous exchange. The right ventricle of the heart pumps blood to the lungs where oxygen enters the bloodstream. Upon oxygenation, blood enters systemic circulation, originating from the left side of the heart. The left ventricle of the heart circulates oxygenated blood throughout the body in the arteries and oxygen is released at capillaries of individual tissues. Here, the tissues excrete waste CO2 which is reabsorbed into the blood and returned by veins to the right ventricle of the heart, returning to pulmonary circulation and completing the circuit. The cardiovascular system also maintains bodily pH, temperature, cellular salt and water content and the transport of hormones and nutrients.
Cardiovascular disease is the leading cause of death globally, accounting for about 30% of deaths worldwide. The term refers to a collection of diseases which affect the heart and blood vessels. These conditions can be genetic in nature or triggered by infection, but the major influences on the development of cardiovascular disease are environmental factors including a high saturated fat intake and a sedentary lifestyle.
One of the most common cardiovascular diseases is atherosclerosis - a condition which is characterized by the buildup of fatty deposits within arterial walls and which can trigger heart attack or stroke through the formation of a blood clot. Damage to the heart muscle caused by a heart attack can alter the contractility of the heart, leading to irregular heartbeats called arrhythmias. A reduced ability of the heart to pump blood around the body can eventually lead to the development of heart failure. Due to the association of cardiovascular disorders, early treatment of these disorders is preferable.
Surgical interventions such as coronary artery bypass and artificial pacemakers are available to treat patients with cardiovascular disease, though the treatments themselves may worsen the overall function of the heart. For many patients, pharmacological intervention is therefore preferable to invasive surgery, particularly for the treatment of early atherosclerosis and high blood pressure. For example, a major breakthrough in the treatment of cardiovascular disease was the development of HMG-CoA reductase inhibitors (statins) for the treatment of raised cholesterol. However, therapy for other diseases such as heart failure and advanced atherosclerosis is lacking and demands further research.
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