The cardiovascular system is a complex network of structures that work together to respond instantaneously to changes in the body. Comprised of a two-sided pump, a network of transport vesicles and a fluid medium, these structures must work synchronously to maintain peak efficiency of all the systems of the body.
Functions
As outlined by Drs. David Mohrman and Lois Heller in "Cardiovascular Physiology," the cardiovascular system serves a number of functions. It is responsible for delivering nutrients and oxygen for metabolic processes and removing the waste byproducts of metabolism from every cell in the body. To aid in metabolic processes, it is necessary for the cardiovascular system to regulate the body's acid-base relationship, maintaining a balance. The regulation of core body temperature is another major function of the cardiovascular system. All of these roles assist the cardiovascular system in achieving its primary goal of maintaining the stable internal environment known as homeostasis.
Heart
The National Heart, Lung and Blood Institute describes the heart as a four-chambered pump. The right and left upper chambers, called atria, receive blood returning from the body and the lungs, respectively. From the upper chambers, blood flows to the lower chambers, the ventricles. When a contraction occurs, the right ventricle sends blood to the lungs while the left ventricle sends blood throughout the rest of the body. This design lends itself to separating the heart into two pump systems. The right atria and ventricle comprise the right pump, called the pulmonary pump, while the two left chambers create the left pump, or the systemic pump.
Blood Vessels
Leading to and from the heart are two types of blood vessels used for transporting the nutrients and waste throughout the body. Arteries are vessels that leave the heart and generally carry oxygen-rich blood. The veins return oxygen-depleted blood to the right atrium. The pulmonary arteries and veins are the exceptions to the oxygenation rule, as the pulmonary arteries carry deoxygenated blood from the heart to the lungs and the pulmonary veins carry oxygenated blood from the lungs to the heart.
The largest of the arteries is the aorta, which originates at the left ventricle and carries blood systemically. The largest of the veins are the inferior and superior vena cava, often called the great veins.
Blood
Blood is used as a transport medium through which nutrients and waste are carried to and from systems of the body. The blood is comprised of approximately 55 percent plasma, mostly water and proteins, and 45 percent formed elements, the majority of which are red blood cells. Among its other functions, the blood is essential in the delivery of oxygen to all other cells of the body, as each red blood cell is capable of carrying roughly 1 billion oxygen molecules.
Variations
Regular exercise leads to adaptations within the cardiovascular system that allow it to function more efficiently. The heart pump becomes stronger and contracts with greater force, allowing more blood, and thus more oxygen and nutrients, to be pumped with every beat. The number of blood vessels and the total blood volume increases as a person moves from a sedentary to an active lifestyle. A sedentary lifestyle leads to various states of cardiovascular disease and decreases the efficiency of the system's components, leading to overall cardiovascular demise.
References
- "Cardiovascular Physiology"; David E Mohrman, PhD; 2003
- National Heart, Lung and Blood Institute: How the Heart Works
