The heart is the powerhouse of the cardiovascular system. It pumps the blood throughout the body; it is a double pump because it pumps blood in two different directions. The main parts of the hearts are the vena cava, the pulmonary trunk, the pulmonary arteries, pulmonary veins, the left and right atrium, the left and right ventricle, the septum, the chordate tendineae and the aorta.
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The heart is shaped kind of like a cone. It is located behind the protective rib cage. The heart is made of cardiac muscle which means it can work constantly without getting tired or needing a break. Your heart is so powerful that in just one hour, it can produce enough energy to life nearly a tonne of weight a yard above the ground and beats approximately 30,000,000 to 40,000,000 times a year.
Blood enters the heart through the vena cava. The inferior vena cava brings in blood from the body and the superior vena cava brings in blood from the head. From the vena cava, blood moves into the right atrium which then sends the blood into the right ventricle through the tricuspid valve.
The right ventricle then sends blood through pulmonary the pulmonary semi lunar valve and into the pulmonary trunk and then into the pulmonary arteries which take the blood to the lungs. Blood must travel to the lungs to gather oxygen. The pulmonary veins carry the oxygen rich blood back to the heart and into the left atrium. The blood is then sent to the left ventricle and then to the aorta where it is pumped into the aorta and to the rest of the body.
The heart does not receive oxygen from the blood that runs through it; it receives blood from coronary arteries. When a coronary artery is blocked, it causes a lack of oxygen to the heart and the heart will die.
However, a blockage in a coronary artery does not always cause a heart attack; it can also cause angina. Angina causes chest pain and pain to the left arm and shoulder. If an individual experiences these symptoms, they should see a physician as soon as possible as surgery may be needed to clear the blockage.
Heart rate is how many times your heart beats per minute. Heart rate is determined by how hard the heart has to work to move blood through the body; the harder the heart has to work, the higher the heart rate. Heart rate is lowest at rest and highest when stressed.
To check your heart rate, find your pulse. You can find your pulse in your wrist (radial artery), neck (carotid artery), back of knee (Popliteal artery), inside of elbow (brachial artery), and in the groin (femoral artery). The wrist and neck are the most common places to find your pulse.
Once you have found your pulse, count how many times your heart beats for fifteen seconds then multiply that number by four. This number represents how many times your heart beats per minute. Average resting heart rate is usually between seventy and eighty beats per minute unless you are Lance Armstrong; he was known to have a resting heart rate of thirty-two to thirty-four beats per minute.
Even though the Ancient Greeks believed that blood vessels carried air, vessels carry blood. You have so many blood vessels in your body that one square inch of skin contains three yards of blood vessels, and if all the blood vessels of the body were laid out end to end they could go around the equator at least two and a half times.
Oxygenated blood travels through arteries. Artery walls have three layers; the first layer is squamous epithelium called tunica intima. The middle layer is the thickest of the three layers and is made up of smooth muscle that can contract to regulate blood pressure and flow; it is called tunica media. The outer layer of artery walls is made of fibrous connective tissue close to the middle layer but is loose connective tissue farther from the middle layer. The outer layer is known as tunica adventitia.
Arteries branch into smaller arterioles. Arterioles are arteries that are barely visible to the naked eye. They are under 0.5mm in diameter. Arterioles branch into capillaries which are extremely small. Capillary walls are only one cell thick; in fact, capillaries are so small that it takes ten of them to make up the width of one human hair. Even though capillaries are very small, they form vast networks. Capillaries are so important because Oxygen and nutrients like glucose are exchanged through them and to the body.
Veins take blood back to the heart. First, venules, small veins, take blood from capillaries and into a vein. The structure of vein walls is quite similar but vein walls are thinner.
Because most veins have to travel upwards to reach the heart, they have to fight gravity to get the blood back up there so veins come equipped with valves which keep blood from flowing downwards. Veins that carry blood from the head do not have valves because blood coming from the head does not have to fight the force of gravity.
If valves don’t close properly it can cause major problems; this is called venous reflux disease. If the veins don’t close, deoxygenated blood can’t get back to the heart. This causes severe tissue damage. Symptoms include aching, burning, swelling, itching, discolouration and ulcers.
There are approximately five litres of blood in the human body and it is the glue that holds the cardiovascular system together; without it there would be no need for a heart of blood vessels. Blood carries oxygen, fights infection and stops bleeding and only two parts of the body can survive without blood: the lens and cornea of the eye. Blood is made up of three parts: red blood cells, white blood cells and platelets.
Red blood cells are made in the bone marrow and there are approximately 5,000,000 red blood cells in just one drop of blood. Red blood cells carry oxygen and carbon dioxide throughout the body. Red blood cells that carry oxygen are red and red blood cells that carry carbon dioxide are purple. They are shaped like concave disks.
Sometimes the body does not have enough red blood cells and this causes anemia. Anemia is usually caused by a lack of iron. Symptoms include lack of energy and a pale skin colour.
White blood cells also originate from the bone marrow. White blood cells are translucent and have a nucleus. White blood cells use proteins and enzymes to fight infections. There are five types of white blood cells: basophils, eosinophils, neutrophils, lymphocytes, monocytes. Though most white blood cells only live for a short time, some live for months or even years.
Platelets are tiny cell fragments that are born in the bone marrow with red and white blood cells. Platelets aid in clotting so when a blood vessel is damaged, platelets come to the rescue and seal the leak.
Sometimes, platelets don’t do their job and cause hemophilia. What that means is clotting does not occur so the slightest bump can cause bleeding to joints. This can cause nerve damage and muscular atrophy.
Though strokes affect the brain, they are really a problem with the circulatory system. They are caused when platelets do their job a little too well and cause a blockage to an artery leading to the head (usually the carotid artery).
If an artery leading to the head is blocked, the brain cannot receive oxygen and this causes a portion of the brain to die. Individuals suffering from a stroke usually have early warning signs like numbness, blindness or slurred speech.
Those warning signs usually exist even after a stroke and a stroke can even cause paralysis but these effects are not permanent. After a stroke, the individual can usually be rehabilitated and the damaged portion of the brain can again become functional but the person may never be the same again.
A common problem with the circulatory system is hypertension. Hypertension is better known has high blood pressure. Though hypertension is usually caused by smoking, lack of exercise, obesity, or diabetes, it can also be hereditary.
A sphygmomanometer-better known as a blood pressure cuff- measures blood pressure-two pressures, actually. The blood pressure cuff measures systolic pressure and diastolic pressure. Systolic pressure is high when the ventricles have contracted and diastolic is low when the ventricles have relaxed. If your diastolic pressure is greater than ninety or systolic pressure is greater than one-hundred-forty, you have high blood pressure.
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High blood pressure is often called a silent killer which means most people aren’t aware they have it until they have a heart attack of stroke. Medications and life style changes can help control blood pressure but the best way to control it is to keep a healthy diet (low in salt), exercise regularly and have your blood pressure checked on a regular basis.
Arrhythmia is a heart condition. It is basically just an irregular heartbeat. Common symptoms are heart palpitations or pounding in the chest; that means your heart is beating irregularly fast. Other symptoms include light headedness, fainting, shortness of breath and fatigue; these are symptoms of your heart beating irregularly slow. If your heart is beating too slowly, your brain does not receive enough oxygen and neither does the rest of your body.
Sometimes, surgeries can be done to get the heart to beat regularly but they aren’t always successful. More common treatments include medications and life style changes.
The very best thing you can do for your cardiovascular system is exercise regularly and be sure to have a healthy diet. This will help to prevent disorders in the cardiovascular system but does not always keep them from occurring.
Though many things can go wrong with the cardiovascular system, worse things would happen without it and all life on earth as we know it would end. Blood goes on a journey so spectacular that none of us can experience it.
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