Cardiovascular Information
The heart can pump 5 or more times the amount of blood during exercise than it does during rest. *Look below for a cool activity to test this out!
The pulmonary artery is the only artery that carries deoxygenated blood, while the pulmonary vein is the only vein that carries oxygenated blood back to the heart.
The sounds “Lub Dub, Lub Dub...” are the sound made by your heart valves closing: the atrioventricular and semilunar valves.
Background:
The cardiovascular system brings oxygen and nutrients to the body’s cells and removes wastes and carbon dioxide. It is made up of the heart, blood, and blood vessels (arteries and veins) that carry blood throughout the body. Without blood circulating throughout the body, organs would not receive the oxygen and nutrients to continue functioning.
The steps of blood delivery and oxygenation are as follows:
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Oxygen rich blood enters the upper left chamber of the heart (left atrium) through four large veins called the pulmonary veins.
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The upper chambers of the heart squeeze together (contract) and the blood is pumped into the lower left chamber of the heart (left ventricle).
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Once blood fills the lower chamber (left ventricle), the ventricles contract and the blood is pushed into a large vessel called the aorta (the largest artery in the body).
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The aorta brings oxygen rich blood to all structures of the body by branching off into smaller and smaller vessels, ultimately becoming networks of capillaries (tiny arteries), called capillary beds.
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Inside the capillary beds, blood releases its oxygen and nutrients to tissues and picks up carbon dioxide and other cellular wastes.
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The oxygen poor blood then leaves the capillary beds and is returned via veins back to the heart. The specific veins that empty oxygen poor blood into the right upper chamber of the heart (right atrium) are called the superior and inferior vena cava.
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Once the right atrium fills up with blood, it pumps the blood into the right lower chamber of the heart (right ventricle).
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After the right ventricle fills up with blood, it also contracts and pushes the blood into a large vessel called the pulmonary artery.
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The pulmonary artery takes the blood to the lungs so that it can pick up more oxygen and drop off carbon dioxide.
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Oxygen rich blood returns to the heart via the pulmonary veins, and the cycle begins again.
Heart Anatomy:
The heart is located at the front and center of the chest cavity, slightly to the left of the breastbone (sternum).
The heart acts as a pump to push blood throughout the body. The inside of the heart is divided into a left and right half by an inner wall called the septum. Each half has two chambers; the top two chambers are called the atria and the two bottom chambers are the ventricles.
Vessels attach to left and right atria to help transport blood from the heart to the rest of the body. The left side of the heart pumps oxygen rich blood into the Aorta, the largest artery in the body. The aorta distributes the blood through progressively smaller arteries to the rest of the body. This is known as systemic circulation.
(Image retrieved from https://www.cardofmich.com/anatomy-human-heart-fun-facts/)
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(Image retrieved from https://www.nagwa.com/en/explainers/912123271719/)
Once oxygen is delivered to all the cells in the body, deoxygenated blood enters into venules (small veins), which combine to form progressively larger veins and ultimately come together into two large veins – the superior and inferior Vena Cava. The superior and inferior vena cava attach to the right atrium and bring oxygen poor blood into the right side of the heart. From there, oxygen poor blood leaves the heart through the pulmonary arteries and enters the lungs, where it picks up more oxygen. From the lungs, oxygen rich blood is returned to the left atrium through the pulmonary veins. The movement of blood between the heart and lungs is known as pulmonary circulation.
To make sure that blood only flows in one direction, valves separate and isolate the chambers. There are four valves inside of the heart: 1) the tricuspid valve separates the right atrium from the right ventricle, 2) the pulmonary valve separates the right ventricle from the pulmonary artery, 3) the mitral valve separates the left atrium from the left ventricle and 4) the aortic valve separates the left ventricle from the aorta. When these valves don’t function properly, there can be serious consequences. Click here to learn more.
Unlike other organs and muscles in the body, the heart is made of cardiac muscle. Like other organs receive oxygen rich blood through arteries, so does the heart. To make sure that the heart has the nutrients and oxygen to continue pumping and delivering oxygen and nutrients to the rest of the body, coronary arteries supply oxygen directly to the heart itself. When these arteries become blocked, the cardiac muscle cells that make up the heart will not be able to function causing a heart attack.
To help the heart contract regularly, the heart also has special “pacemaker” cells. These cells are organized into several clusters throughout the heart. The sinoatrial (SA) node that is found in the right upper chamber of the heart (right atrium). This “pacemaker” of the heart determines how often the heart beats. In the average adult, this happens at a rate of 60 to 100 beats per minute.
When the pacemaker of the heart generates a signal, it causes both upper chambers (atria) of the heart to squeeze together (contract). Once this signal is generated, it travels to another node called the atrioventricular (AV) node in the wall of the heart (septum). Once the signal hits the AV node, it keeps travelling down a special group of electrical fibers called the bundle of His. The bundle of His splits off into smaller pathways called bundle branches which extend into the right and left lower chambers of the heart (ventricles) and cause them to contract. Through this process, the heart can push blood to where it needs to go.
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(Image retrieved from http://www.pathophys.org/physiology-of-cardiac-conduction-and-contractility/)
Cardiovascular Disease:
The leading cause of death in America is heart disease, of which coronary artery disease (CAD) is most prominent. CAD occurs when a buildup of plaque in the blood vessels of the heart constricts blood flow, resulting in lack of oxygen to muscle tissue. Symptoms of the disease range from mild to severe, with one of the most severe symptoms being Myocardial Infarction, also known as a heart attack. Some risk factors for CAD include the following:
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family history of CAD
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smoking tobacco
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eating an unhealthy diet
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being physically inactive
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being overweight
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having high blood pressure
The best ways to take care of your heart relate to regulating blood pressure and cholesterol through diet and exercise. A prolonged diet that is high in cholesterol leads to a buildup of plaque within the arteries, which can have serious side effects if arteries get blocked. For individuals with high blood pressure, the heart pumps extremely hard to circulate blood throughout the body, which can lead to vessels becoming damaged. To learn more information about heart disease and its associated symptoms, check out these links:
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Myocardial Infarction:
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2019 Heart Disease and Stroke Statistics from the American Heart Association:
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Referred Pain:
Developments:
Check out these sources for new developments in cardiac treatment:
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Pig Heart Transplant:
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Stem cells: