Heart: Simplified for layman

The heart is one of the most important organs in the human body, continuously pumping blood around our body through blood vessels. Your heart is located in your chest and is well protected by your rib cage. The study of the human heart and its various disorders is known as cardiology. The heart is made up of four chambers, the left atrium, right atrium, left ventricle and right ventricle. There are four valves in the human heart, they ensure that blood only goes one way, either in or out. Blood that leaves the heart is carried through arteries. The main artery leaving the left ventricle is the aorta while the main artery leaving the right ventricle is the pulmonary artery. Blood going towards the heart is carried through veins. Blood coming from the lungs to the left atrium is carried through the pulmonary veins while blood coming from the body to the right atrium is carried through the superior vena cava and inferior vena cava. You might have felt your own heart beating, this is known as the cardiac cycle. When your heart contracts it makes the chambers smaller and pushes blood into the blood vessels. After your heart relaxes again the chambers get bigger and are filled with blood coming back into the heart. Electricity going through your heart makes the muscle cells contract. You might have watched television shows or movies where a patient in a hospital is attached to an electrocardiogram (ECG). You might recognize it as the machine with a line moving across a screen that occasionally spikes (or remains flat when a patient is dying). This machine can measure the electricity going through a patient’s heart. A doctor can use the information to know when a patient is having heart rhythm problems or even a heart attack. Heart attacks cause scar tissue to form amongst normal heart tissue, this can lead to further heart problems or even heart failure. 1. CORONARY CIRCULATION The heart muscle itself needs blood. The graphic above identifies arteries (red) supplying oxygenated blood to the heart tissue, and veins (blue) removing deoxygenated blood. Coronary artery disease is associated with reduced blood flow to these vessels. 2. PULMONARY CIRCULATION Veins carry oxygen-depleted blood (blue) from the body to the heart, which pumps it to the lungs. The lungs enrich the blood with oxygen (red) and return it to the heart to be pumped to the rest of the body. 3. CEREBRAL CIRCULATION The brain comprises only 2% of the body's weight but receives 20% of the blood supply. Over 150,000 people have strokes each year, largely resulting from blockages in the arteries and veins. Unimpeded circulation of blood to and from the brain is critical to health. 4. RENAL CIRCULATION Approximately 20% of blood output from the heart goes to the kidneys. The kidneys cleanse and detoxify blood and also serve an excretory function sending urine to the bladder. Renal circulation significantly contributes to overall circulatory health. 5. HEPATIC PORTAL CIRCULATION Blood from the entire digestive area including the intestines, stomach, pancreas, and gall bladder passes through the liver for cleansing and storing of nutrients. This function is often overlooked as critical to the overall circulatory system. 6. SYSTEMIC CIRCULATION Blood flows to the rest of the body including the extremities. Major arteries and veins supplying the arms are pictured above.