Heart Disease
The heart is at the center of your circulatory system, which delivers blood to all areas of your body. An electrical system regulates the heart and uses electrical signals to contract the heart's walls. When the walls are contracting, blood is being pumped into the circulatory system.
The heart is sort of like a pump or two pumps in one. The right side of your heart receives blood from the body and pumps it to the lungs. The left side of the heart does the exact opposite: It receives blood from the lungs and pumps it out to the body.
How does the heart beat? Before each beat, your heart is filled with blood. Then its muscle contracts to squirt the blood along. When the heart contracts, it squeezes - try squeezing your hand into a fist. That's sort of like what your heart does so it can squirt out the blood. Your heart does this all day and all night, all the time.
The heart is the organ that supplies blood and oxygen to all parts of the body. Its size is about the size of a clenched fist, weighs approximately about 10.5 ounces and is shaped like a cone. The heart is located in the chest cavity just posterior to the breastbone, between the lungs and superior to the diaphragm. The heart is surrounded by a fluid filled sac called the pericardium. Blood is pumped away from the heart through the arteries and returns to the heart through veins. The major artery of the body is the aorta and the major veins of the body are the vena cava.
From all parts of the body, the heart receives blood. Blood is pumped through the pulmonary artery going to the lungs where it picks up fresh oxygen.
The heart is divided by a partition or septum into two halves. The halves are in turn divided into chambers. The upper two chambers of the heart are called atria and the lower two chambers are called ventricles. Valves allow blood to flow in one direction between the chambers of the heart.
The heart is divided into three layers - the epicedium, myocardium and endocardium. The epicardium is the outer layer of the wall of the heart. It is composed of connective tissue covered by epithelium. The epicardium is also known as the visceral pericardium. It provides an outer protective layer for the heart. The myocardium is the muscular middle layer of the wall of the heart. It is composed of spontaneously contracting cardiac muscle fibers which allow the heart to contract. It stimulates heart contractions to pump blood from the ventricles and relaxes the heart to allow the artria to receive blood. The endocardium is the inner layer of the heart. It consists of epithelial tissue and connective tissue. It lines the inner cavities of the heart, covers heart valves and is continuous with the inner lining of blood vessels.
These are the four types of valves that regulate blood flow through your heart:
- The tricuspid valve regulates blood flow between the right atrium and right ventricle.
- The pulmonary valve controls blood flow from the right ventricle into the pulmonary arteries, which carry blood to your lungs to pick up oxygen.
- The mitral valve allows oxygen-rich blood from your lungs pass from the left atrium into the left ventricle.
- The aortic valve opens the passage for oxygen-rich blood to pass from the left ventricle into the aorta, your body's largest artery, where it is delivered to the rest of your body.
By: Yoej
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