Total Posts: 47628
United Kingdom, United Kingdom
Ever*yone knows that the heart is a vital organ. We cannot live without our heart. However, when you get right down to it, the heart is just a pump. A complex and important one, yes, but still just a pump. As with all other pumps it can become clogged, break down and need repair. This is why it is critical that we know how the heart works. With a little knowledge about your heart and what is good or bad for it, you can significantly reduce your risk for heart disease.
Heart disease is the leading cause of death in the United States. Almost 2,000 Americans die of heart disease each day. That is one death every 44 seconds. The good news is that the death rate from heart disease has been steadily decreasing. Unfortunately, heart disease still causes sudden death and many people die before even reaching the hospital.
The heart holds a special place in our collective psyche as well. Of course the heart is synonymous with love. It has many other associations, too. Here are just a few examples:
* have a heart - be merciful
* change of heart - change your mind
* to know something by heart - memorize something
* broken heart - to lose love
* heartfelt - deeply felt
* have your heart in the right place - to be kind
* cry your heart out - to grieve
* heavy heart - sadness
* have your heart set on - to want something badly
Certainly no other bodily organ elicits this kind of response. When was the last time you had a heavy pancreas?
In this article, we will look at this important organ so that you can understand exactly what makes your heart tick.
The Human Heart
The heart is a hollow, cone-shaped muscle located between the lungs and behind the sternum (breastbone). Two-thirds of the heart is located to the left of the midline of the body and 1/3 is to the right
The heart is a hollow, cone-shaped muscle located between the lungs and behind the sternum (breastbone).
When someone listens to your heart with a stethoscope the sound is often described as lub-dub lub-dub. The first heart sound (lub) is caused by the acceleration and deceleration of blood and a vibration of the heart at the time of the closure of the tricuspid and mitral valves. The second heart sound (dub) is caused by the same acceleration and deceleration of blood and vibrations at the time of closure of the pulmonic and aortic valves.
The apex (pointed end) points down and to the left. It is 5 inches (12 cm) long, 3.5 inches (8-9 cm) wide and 2.5 inches (6 cm) from front to back, and is roughly the size of your fist. The average weight of a female human heart is 9 ounces and a male's heart is 10.5 ounces. The heart comprises less than 0.5 percent of the total body weight.
The heart has three layers. The smooth, inside lining of the heart is called the endocardium. The middle layer of heart muscle is called the myocardium. It is surrounded by a fluid filled sac call the pericardium.
The heart is divided into four chambers:
1. right atrium (RA)
2. right ventricle (RV)
3. left atrium (LA)
4. left ventricle (LV)
The heart is divided into four chambers.
Each chamber has a sort of one-way valve at its exit that prevents blood from flowing backwards. When each chamber contracts, the valve at its exit opens. When it is finished contracting, the valve closes so that blood does not flow backwards.
5. The tricuspid valve is at the exit of the right atrium.
6. The pulmonary valve is at the exit of the right ventricle.
7. The mitral valve is at the exit of the left atrium.
8. The aortic valve is at the exit of the left ventricle.
When the heart muscle contracts or beats (called systole), it pumps blood out of the heart. The heart contracts in two stages. In the first stage, the right and left atria contract at the same time, pumping blood to the right and left ventricles. Then the ventricles contract together to propel blood out of the heart. Then the heart muscle relaxes (called diastole) before the next heartbeat. This allows blood to fill up the heart again.
The right and left sides of the heart have separate functions. The right side of the heart collects oxygen-poor blood from the body and pumps it to the lungs where it picks up oxygen and releases carbon dioxide. The left side of the heart then collects oxygen-rich blood from the lungs and pumps it to the body so that the cells throughout your body have the oxygen.