Cardiovascular System 101 | Dr. Sinatra's HeartMD Institute

By Stephen T. Sinatra, M.D., F.A.C.C., F.A.C.N., C.N.S., C.B.T.

The heart, blood, and blood vessels in your body make up your dynamically efficient cardiovascular system. The cardiovascular system also comprises the greater circulatory system which includes your pulmonary circulation and lymphatic systems.

The primary function of the cardiovascular system is to circulate blood to all cells and tissues of the body. Such circulation of blood ensures the delivery of life-sustaining oxygen and nutrients to cells, as well as the efficient removal of metabolic waste products from them. In consideration of this responsibility, the health and integrity of your heart and blood vessels are paramount for overall health maintenance.

Before transporting blood throughout the body, the heart sends it to the lungs for oxygenation. It then pumps the blood to all the cells of the body through a complex system of arteries, arterioles, and capillaries. Blood entering the capillaries exchanges essential nutrients and oxygen for cellular waste products such as carbon dioxide. While cells need oxygen and glucose for basic metabolism, they also use vitamins, minerals, amino acids, and cholesterol, to name a few materials delivered by the blood, for synthesis of other necessary substances.

The blood travels back from the capillaries to the heart through a system of venules and veins. Blood carries carbon dioxide back to the lungs to be expelled as breath, and filters other waste products through the kidneys for excretion through urine. All blood eventually returns to the heart through various inward-branching venules, and then veins to begin the cycle again. So much happens in a single heartbeat!

In the average adult, this entire cycle of blood circulation occurs more than once per second, at around 70 times per minute! On average, that’s 100, 800 times a day and over 36 million times per year! Think about the millions of cells in your body that depend on your heart’s lightening-speed capability to feed and detoxify them, and imagine how any impediments to this circulatory process, such as inflamed blood vessels, might deplete your health.

Hercules the Heart

Structurally, your heart is a fist-sized muscle consisting of four chambers: the right and left atria, which receive blood, and the right and left and ventricles, which propel it out to the rest of the body. The four chambers are conjoined by valves which ensure that blood flows in the right direction. While the tricuspid valve separates the right atrium and ventricle, the mitral valve lies between the left atrium and ventricle. Your heartbeat is actually the sound of the valves closing shut.

The heart is composed of cardiac muscle which constantly contracts in rhythm set by its pacemaker. The pacemaker, or sinoatrial node, speeds up or slows down heartbeat in response to signals sent by various nerves corresponding with the sympathetic and parasympathetic branches of the autonomic nervous system.

The effort with which the heart must beat correlates with blood vessel health. Blood vessels that are hardened, narrowed, and/or clogged force the heart to work harder to propel blood to all the body’s cells which depend on it for sustenance. Hearts which strain to accomplish their function become enlarged and energy-depleted. Thus, cardiovascular health depends not only on the strength and energy of the heart, but on blood vessel integrity.

Branching Avenues

Branching throughout the body, blood vessels are the passage routes for vital life substances. The blood vessels comprise a living, breathing organ made of smooth muscles which contract in metronomic response to the heart. They literally connect all parts of the body to the heart. As the heart requires an incredible amount of energy to circulate blood throughout the body, it contains its own system of blood vessels, the coronary arteries, veins, and capillaries, from which it obtains fresh blood.

Each time your heart contracts it forces blood into the aorta, the body’s main artery. The aorta branches into other arteries that service the body as well as the coronary arteries, which feed the heart. Arteries further diverge into arterioles, which then split into capillaries, where cells can exchange nutrients for waste products in the fluid that surrounds them. This exchange is accomplished through small spaces in the endothelial lining of the capillaries.

Blood returns from the capillaries to the heart through the various inward branching venules, then veins, and ultimately through the superior and inferior vena cavas, which deliver blood from the upper and lower extremities, respectively. The heart then sends the blood to the lungs via the pulmonary artery, for oxygenation and removal of carbon dioxide. Once oxygenated, the blood travels through the pulmonary vein into the left side of the heart to be pumped through the body again.

The integrity of blood vessel structures is paramount to health. Blood vessels must remain smooth and unobstructed to permit blood to flow easily through the body. Of particular importance to health is the innermost layer of blood vessel walls: the endothelium. The endothelium, a permeable lining approximately one-cell thick, is extremely delicate and sensitive to injury, especially inflammation.

Blood vessels become inflamed over time as a result of unhealthy lifestyle habits and environmental exposure to contaminants and pollutants. Smoking, overeating refined and otherwise processed foods containing sugars, unnatural fats, and chemical preservatives, as well as not getting enough fresh fruits and vegetables, water, and physical activity all contribute to inflammation of blood vessels, as does stress associated with work, relationships, and financial pressures, for example. When chronic, inflammation sets the stage for cardiovascular disease (CVD).

Inflammation of the endothelium can eventually evolve into plaque. Once damaged, the endothelium becomes porous and attracts fatty particles such as cholesterol. These particles which lodge within the endothelium interfere with biological processes and, when in contact with free radicals, transform into oxidized LDL cholesterol. An alarm goes off: the immune system responds by releasing chemicals that instigate more inflammation and result in a chain of chemical response throughout the endothelium.

Because oxidized LDL cholesterol is reactive to immune cells (macrophages), the inflamed site becomes a magnet for chemicals, waste products and toxins, and eventually results in a hardened plaque to contain them all. Stable plaques may spread and narrow arteries, burdening the heart, while plaques that become unstable because of additional inflammation can rupture and cause blood clots which, if completely blocking blood flow, can result in a stroke or heart attack.

Cardiovascular health, then, depends on endothelial health. A healthy endothelium produces chemical substances that allow for the normal expansion and relaxation of blood vessels. Healthy arteries stretch easily, are completely clear, not narrowed, and free from obstruction. Elastic walls ensure that large volumes of blood can be sent through blood vessels without causing blood pressure to significantly rise. As high blood pressure is a risk factor for CVD, help avoid it through endothelial preservation.

The River of Life

Your blood is comparable to seawater – like the ocean it contains 57 minerals, but it also carries vitamins, hormones, proteins and other constituents. Each droplet within the ten to twenty pints of blood in our bodies contains approximately 50 million hemoglobin-containing red blood cells. Hemoglobin, an iron-rich pigment, is responsible for delivering oxygen to tissues. It attaches to oxygen to form oxyhemoglobin, which cells dissolve and use for energy production. Blood cells are contained within blood plasma, which consists mostly of water.

How fast blood flows depends on its viscosity, or relative stickiness and thickness; thicker and stickier blood clots more easily. Hyperviscosity characterizes blood that is sticky or sludgy enough to cause blood platelets to clump together. Blood platelets are specialized constituents which amalgamate in response to inflammation and injury.

While clotting serves a beneficial purpose, for example by preventing loss of too much blood from a laceration wound, it can also cause a stroke or myocardial infarction (heart attack) by blocking blood vessels which supply the heart, brain, lungs, and other vital organs with vital oxygen and nutrients. Hyperviscous blood results in blood platelet adhesion in the absence of injury, and contributes to rigidity and calcification of blood vessel walls. Over time, these changes strain on the already overly-responsible heart.

There are many causes of sticky blood, including genetics, lack of exercise, environmental toxins, and deformities to blood cells resulting from aging, diabetes and high levels of both Lp(a) and homocysteine. Excess iron in the blood can also lead to hyperviscosity. Inflammation especially causes sticky, or hypercoaguable, blood.

As mentioned earlier, inflammation in blood vessels can advance the formation of unstable plaques. Ruptured plaques may cause existing clots to break off, travel through the bloodstream, and possibly block vessels. Ruptured plaques will also activate fibrin, a clotting agent that will further thicken the blood and continue the cycle of inflammation, plaque formation, and blood clotting.

Toxic blood is filled with components that both engender and indicate inflammation. Such substances, which serve beneficial clot-promoting purposes in acute injury situations, include homocysteine, lipoprotein(a) or Lp(a), C-reactive protein (CRP), fibrinogen (which converts into fibrin), and ferritin (iron). Your doctor can measure levels of these inflammatory markers in your blood.

The body is equipped with a natural anti-clotting mechanism, an enzyme called plasmin, which deconstructs excess fibrin to restore blood viscosity balance. It also battles excess levels of homocysteine and Lp(a) through detoxifying vitamins derived through the diet or supplements. When the amount of arterial inflammation exceeds the body’s natural resources to combat it, external reinforcements, such as blood-thinning and clot dissolving medications or natural supplements, may be necessary to keep blood healthy. Always consult your doctor before changing medication dosages or adjunctively taking supplements.

Wrapping it up….

While cholesterol and blood pressure are significant health concerns, they are symptomatic of greater structural and functional problems arising within your cardiovascular system. Silent inflammation within blood vessels can set the stage for cardiovascular diseases by detrimentally affecting all cardiovascular structures. Inflammation can lead to hardened arteries and formation of clots, factors which together strain the heart, toxify and thicken the blood, and possibly result in stroke or heart attack.

Preventing or assuaging blood vessel inflammation through a Heart Healthy Lifestyle is within your reach and may save you a frightening visit to the doctor or emergency room. Help keep inflammation at bay through commitment to an anti-inflammatory diet and appropriate supplementation, moderate exercise, and stress management, as well as mind-body and alternative medicine. If you are taking any medication for a cardiovascular condition, be sure to consult your doctor before consuming additional supplements, as drug-interaction issues may be present.

Be sure to check out future articles in this section addressing concerns about cholesterol, blood pressure, and other cardiovascular health issues. See Reverse Heart Disease Now, Lower Your Blood Pressure in Eight Weeks, and Heartbreak and Heart Disease for more information about your cardiovascular health.