|Cholesterol And Heart Disease|
In an instant, heart disease can tear a family apart. Abruptly, it can sever ties among spouses, parents and children, friends, neighbors, and other loved ones. The good news in this grim scenario is that with knowledge and with action, you can take significant steps toward reducing the heavy toll exacted by this disease. Understanding what heart disease is and how cholesterol contributes to it is an important first step.
What Is Heart Diseaseall
A healthy heart and circulatory system are something that many people take for granted-that is, until one day they experience chest pains or breathlessness and realize that something in the body is no longer working the way that it should. But what keeps a heart healthy? Or, what causes a heart to lose its ability to function properly?
The Structure and Function of the Heart
Before we can clearly understand what is going on when the heart dysfunctions, it's necessary to have a basic comprehension of its structure and function. The human heart lies in the upper left center of the chest, next to the lungs. It has four chambers: the right atrium and the left atrium on the top, and the right and left ventricles on the bottom. Blood flows into the right side of the heart and out of the left side. To guide the flow of blood in one constant direction, each chamber connects to the next one through valves that open when the heart contracts.
Blood that no longer contains oxygen enters the right side of the heart through a large vein called the vena cava. This deoxygenated blood flows into the right atrium. When the heart contracts, this blood flows through the tricuspid valve into the right ventricle. From the right ventricle, the blood enters the pulmonary artery via the pulmonary valve to become freshly oxygenated in the lungs. The newly oxygen-rich blood leaves the lungs and flows back to the heart's left atrium through the pulmonary vein. With the next contraction, the mitral valve opens and blood flows into the left ventricle, the strongest section of this miraculous muscular pump. When this section contracts, blood then rushes through the aortic valve into the aorta to repeat its journey around the body. This circulatory process continues automatically for as long as you live.
An electrical stimulus regulates the heartbeat. In the right atrium, a specialized group of cells-known as the sinoatrial node, the SA node, or the sinus node-triggers the electrical impulses that cause the chambers of the heart to contract and push the blood along its path. The rate of the electrical impulses is regulated, but it can vary depending on different chemical stimulators in the body. In this manner, a healthy heart can respond to different needs as required by the demands of life.
For example, when you are reclining on a couch in a primarily horizontal position, your heart does not have to work as hard to circulate blood around your body since it does not have to flow against gravity. When you stand up from the couch-let's say to get a drink from the refrigerator-your heart must work harder to pump blood against gravity and to your working muscles. In a person with a healthy heart, all of these adaptations occur effortlessly. We never pause to think about how our movements increase the demands on our circulatory system; we simply go and assume that our body will be able to respond smoothly and easily.
The function of the heart and the circulatory system is to keep blood flowing continuously at a consistent rate. This ensures delivery of essential oxygen and nutrients to the body's tissues. Other processes that occur simultaneously through the circulation include the removal of waste products from cells back to the lungs, liver, and kidneys for filtering. A healthy nervous system is also important to a healthy circulatory system, since it affects heart rate and vessel function.
A healthy heart is an electronically regulated muscular pump that is about the size of a fist. Each day and night, the average heart beats approximately 100,000 times and pumps 2,000 gallons of blood. Over a normal lifespan, the heart will beat more than 2.5 billion times.