The Cardiovascular System (sometimes called the circulatory system) consists of the heart, blood vessels, and lymphatics. The heart provides the power to move the blood and the vascular system represents the network of branching conduit vessels through which the blood flows. This network brings life-sustaining oxygen and nutrients to the body's cells, removes metabolic waste products, and carries hormones from one part of the body to the other. Right off the bat, what immediately catches my interest about this system is the heart. On a mechanical level, this mystical love pump is capable of greater reliability than some of the best pumps ever built by humans and can easily withstand 80 to 100 years of continuous service without ever stopping for repairs. Its output is also fully adjustable on demand, over a range of about 5 to 25 liters of blood per minute. On another level, the heart is an important organ of perception. Both recent and ancient wisdom invites us to think of the heart as an organ of sensitive perception and integration. In our therapeutics class on cardiovascular wellness, Betzy spoke about the heart's connection to both our nervous and endocrine systems and its ability to perceive electromagnetic fields (what small people call - vibes) from people, animals, plants and the environment. Betzy compared the cardiovascular system to an internal tree of life, that connects and responds to our external world as well as internal needs. Unfortunately, in our modern life it's challenging to get the same amount of movement and time spent outdoors that our ancestors did. We are a society that predominately lives in our heads rather than our bodies and we are far more sedentary and indoor dwelling and head centered than we evolved to be. Additionally, our culture doesn't support strong community ties, love for the natural world and connection - even to our closest loved ones. When we don't exercise our intuitive faculties or emotional ones either, we start to lose our strength and vitality. It's no wonder that the cardiovascular disease is the most common serious, life-threatening illness we face worldwide. As with any muscle, lack of use leads to deterioration, inflexibility and lack of responsiveness - the opposite of vitality and resilient health. Let's take a closer look at the inner workings of this system to gain some more insight into what it's all about. Blood: Did you know that 7-8% of human body weight is from blood? In adults, this amounts to 4.5-6 quarts of blood. This essential fluid carries out the critical functions of transporting oxygen and nutrients to our cells and getting rid of carbon dioxide, ammonia, and other waste products. In addition, it plays a vital role in our immune system and in maintaining a relatively constant body temperature. Blood is a highly specialized tissue composed of more than 4,000 different kinds of components. Four of the most important ones are red cells, white cells, platelets, and plasma. All humans produce these blood components--there are no populational or regional differences. Red blood cells transport oxygen and carbon dioxide to and from body tissues. They contain hemoglobin, the oxygen carrying substance that gives blood its red color. These cells have an average lifespan of 120 days and are released by bone marrow. White blood cells participate in the body’s defense and immune systems. These five types of cells are classified as granulocytes and agranulocytes. Platelets are small, colorless, disk-shaped cytoplasmic fragments spit from cells in bone marrow. These fragments have a lifespan of about ten days and perform three vital functions which includes initiating contraction of damaged blood vessels to minimize blood loss, forming hemostatic plugs in injured blood vessels and with plasma, providing materials that accelerate blood coagulation. Plasma is the clear, straw-colored liquid portion of blood that remains after red blood cells, white blood cells, platelets and other cellular components are removed. It is the largest component of human blood, comprising about 55 percent, and contains water, salts, enzymes, antibodies and other proteins. The Pulmonary and Systemic Circuits: The above diagram shows the general structure of the entire cardiovascular system. Note that the heart is pumping blood through the lungs (the pulmonary circuit) and through the rest of the body to all the cells (the systemic circuit) simultaneously. Each circuit has its own set of blood vessels. Let’s follow the pulmonary circuit first:
The system circuit serves the rest of the body. When blood enters the left ventricle, it begins the systemic circuit, which takes it to the rest of the body.
Arteries, Arterioles, Capillaries, Venules, and Veins- Who are they? As described in the pulmonary and systemic circuits, when blood leaves the heart it is pumped into large, muscular, thick-walled arteries. Arteries transport blood away from the heart. The larger arteries have a thick layer of muscles because they must be able to withstand the high pressure generated by the heart. Arteries branch again and again, so the farther the blood moves from the heart, the smaller in diameter the arteries become. Eventually the blood reaches the smallest arteries, called arterioles (literally, “little arteries”). The largest artery in the body, the aorta, is about 2.5 centimeters (roughly 1 inch) wide. In contract, arterioles have a diameter of 0.3 millimeter or less, about the width of a piece of thread. By the time blood throws through the arterioles, blood pressure has fallen considerably. Consequently, arterioles can be simpler in structure. Arterioles connect to the smallest blood vessels, called capillaries. Capillaries are thin-walled vessels that average only about one-hundredth of a millimeter in diameter- not much wider than the red blood cells that travel through them. In fact, they are so narrow that red blood cells often have to pass through them in single file or even bend to squeeze through them. From the capillaries, blood flows back to the heart through venules (small veins) and veins. LIke the walls of arteries, the walls of veins consist of three layers of tissue. However, the outer two layers of the walls of veins are much thinner than those of arteries. Veins also have a larger lumen (are larger in diameter) than arteries. The anatomical differences between arteries and veins reflect their functional differences. As blood moves through the cardiovascular system, the blood pressure becomes lower and lower. The pressure in veins is only a small fracture of the pressure in arteries, so veins do not need nearly as much wall strength (provided by muscle and connective tissue) as arteries. In addition to their transport function, veins serve as a blood volume reservoir for the entire cardiovascular system. Nearly two-thirds of all the blood in your body is in your veins. Very cool! The Hepatic Portal System The hepatic portal system is the system of veins comprising the hepatic portal vein and its tributaries. This system is responsible for directing blood from parts of the gastrointestinal tract to the liver. Substances absorbed in the small intensive travel first to the liver for processing before continuing to the heart. Not all of the gastrointestinal tract is part of this system but overall it extends from about the lower portion of the esophagus to the upper part of the anal canal. It also includes venous drainage from the spleen and pancreas. Blood pressure is the force that blood exerts on the wall of a blood vessel as a result of the pumping action of the heart. Blood pressure is not the same in all blood vessels (or people for that matter - like this bizarre dude in the picture above). heh. When health professionals measure your blood pressure they are assessing only the pressure in your main arteries. From a clinical standpoint, blood pressure gives valuable clues about the relative volume of blood in the vessels, the condition or stiffness of the arteries, and the overall efficiency of the cardiovascular system. Trends in blood pressure over time are a useful indicator of cardiovascular health. Blood pressure higher than normal is called hypertension and is a significant risk factor for cardiovascular disease. The greater pressure, the greater the strain on the cardiovascular system. Blood vessels react to the pounding by becoming hardened and scarred, which makes them less able to stretch during systole. Hypertension also places a greater strain on the heart, because the work it must do is directly proportional to the arterial pressure against which it must pump. Smoking, a sedentary lifestyle, obesity, heredity, persistent emotional stress, heavy alcohol consumption and other factors can increase the risk of hypertension. How this all relates to Herbal Medicine:
As with so many aspects of human health, the basic approach to both prevention and management of cardiovascular issues or disease is undertaking appropriate exercise, mind-body balance, and diet - with herbs to support more specific aspects of health health, as needed. Regular cardio exercise strengthens the function of the heart while meditation, breathwork and exercises with a mind-body component like yoga and tai chi have been shown to reduce heart-damaging stress and slow or even reverse heart disease. Heart tonics with plants like rose, hawthorn, rooibos, hibiscus, linden and cacao have all been shown to be beneficial, with broad-reaching cardiovascular benefits. A heart healthy diet full of berries, leafy greens and vegetables is a powerful component of strong cardiovascular health. Remember kids, it's never too late to:
0 Comments
Leave a Reply. |
AuthorThe adventures, studies, and musings of a student at the Vermont Center for Integrative Herbalism.
Categories
All
|