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Basic Anatomy and Function of the Cardiovascular System
Basic Parts and Functions of the Cardiovascular System
The Cardiovascular System is made up of the heart, blood vessels and blood. The heart is a muscle responsible for pumping the blood through the blood vessels, to and from every cell in the body.
Blood is made up of red blood cells, white blood cells, platelets and plasma. Plasma is the liquid part of blood which carries hormones, proteins, nutrients, salts, and gases- both that the cells of the body needs, and that need to be removed from the cells, to nourish, prevent toxicity and maintain the acid-base balance of the body. Red blood cells are specialized to deliver oxygen to the cells. Oxygen is what gives them their red color. When oxygen is depleted from the blood, the blood turns blueish. White blood cells are responsible for fighting infections and fighting against foreign materials in the body. The last type of cells in blood are platelets, which are responsible for the clotting property of blood. Platelets allow you to form scabs.
Types and Functions of Blood Vessels
Throughout the body, there is a network of blood vessels. They are larger nearest to the heart and branch off to smaller and smaller vessels.
Arteries carry oxygen-rich blood away from the heart. As they branch off, they eventually lead to microscopic vessels called arterioles, which connect to smaller yet beds of capillaries. Capillaries have extremely thin walls which allow for the exchange of materials between the blood and the interstitial fluid between the cells. Capillaries connect the path of oxygen-rich blood from the arterioles, to the path of oxygen-depleted blood through the venules. Venules are microscopic blood vessels which lead to larger blood vessels, called veins, to return the blood to the heart.
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Does the heart do all the work of moving the blood through the blood vessels in your entire body?
It does most of it, but the blood vessels have structures to aid in this as well. Your arteries are more elastic and are stretched slightly as they fill with blood. Their elasticity allows them to contract again, which helps to push the blood along the arteries. Veins, particularly in the legs, contain valves to fight against gravity pulling the blood in the opposite direction. Each of these functions aids in the work that the heart does to move blood through the entire body.
Wait... Pulmonary arteries carry oxygen-depleted blood?
You may have learned to tell the difference between veins and arteries by whether the blood in them is oxygen-rich or oxygen-depleted. That's true everywhere except the Pulmonary Arteries and Veins. The actual definition of an artery is a blood vessel which travels away from the heart, and likewise, a vein is a blood vessel which travels to the heart. In the Systemic Circuit of the heart, that always means that arteries carry oxygen-rich blood, and veins carry oxygen-depleted blood. The exact opposite is the case in the Pulmonary Circuit of the heart. The right side of the heart contains oxygen-depleted blood- the opposite of the oxygen-rich blood in the left side of the heart. Therefore, the arteries leading away from the right side of the heart, to the lungs, carry oxygen-depleted blood, while the veins leading back to the left side of the heart, from the lungs, carry oxygen-rich blood.
Anatomy and Physiology of the Heart
The heart is made up of two closed circuits. The Pulmonary Circuit, the right side of the heart, pumps oxygen-depleted blood returned from the body through the veins, to the lungs to be replenished with oxygen. The Systemic Circuit, the left side of the heart, pumps oxygen-rich blood returned from the lungs, to the systems of the body through the arteries.
Each side of the heart contains an atrium and ventricle, with a valve at the end of each to control the direction of the blood flow. Both atria contract simultaneously, pumping their blood into the corresponding ventricle. About one-tenth of a second later, both ventricles contract simultaneously, pumping their blood to the lungs and the rest of the body, respectively. This repeated action is called the cardiac cycle, which gives you your heartbeat.
The path of blood through the heart
Beginning with oxygen-depleted blood returning to the right atria through the superior and inferior vena cava- the veins that connect directly to the heart- blood is pumped from the right atria to the right ventricle. About one-tenth of a second later, that blood in the right ventricle is pumped out to the lungs through the right and left pulmonary arteries, where is releases it's carbon dioxide and is replenished with oxygen. The oxygen-rich blood then returns to the left atrium through the pulmonary veins. The left atrium then pumps the blood into the left ventricle. About one-tenth of a second later, the left ventricle pumps that blood to the rest of the body through the aorta, the artery that connects directly to the heart.
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