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They are places where veins and/or blood vessels pass close enough to the surface of the skin - for someone to feel the blood pulsing through the body.
they need to open and close to allow blood to flow through the heartto prevent blood from flowing backwards when traveling through the heartThe heart has four chambers where blood is pumped. The four heart valves are the tricuspid, pulmonary, mitral, and aortic. The valves open and close to let the blood flow in only one direction.to pump blood throughout the body!To keep blood flowing they close between beats so it doesn't drain outThe purpose of the heart valves is to avoid back flow of blood.
A leaking aortic valve means that when your hears pumps blood through the valve, that the valve does not close of properly when it should. This causes your heart to have to work harder because some of the blood it pumps leaks back into the heart and needs to be pumped out again.
There are valves in the heart which open and close that allow the blood to be pumped in one direction only. See the related link for more information.
The heart and lungs are so close together because the lungs have oxygen that are pumped into the heart so it can go into the blood stream. The lungs don't have blood but they transmit oxygen to the heart for the blood stream.
The valves have to open to let blood flow into a chamber, and close before the blood flows back. If the valves do not open and close precisely on schedule, or if they fail to open or close completely, the blood will not flow efficiently. This can cause fluctuations in blood pressure, lack of flow to organs, or damage to the muscles of the heart. For example, if the aortic valve between the heart and the aorta does not close after the left ventricle contracts, there will be back pressure into the ventricle, less blood pumped out of the heart, and lower pressure in the arteries.
Blood is pumped back into the left atrium (the wrong direction) as well into the aorta (the right direction)
The right atrium and right ventricle pump deoxygenated blood from the body to the lungs via the pulmonary artery. Carbon dioxide is then exchanged for oxygen in the capillaries of the lungs. The oxygenated blood then travels from the lungs, via the pulmonary vein to the left atrium and left ventricle, and then is pumped to the rest of the body to feed the cells.Answer 2:The heart is a four-chambered muscular organ that pumps blood to all parts of the body. A wall, called a septum, divides the heart into a right and left side. Each side is further divided in to an upper chamber (called the atrium) and a lower chamber (called the ventricle). These chambers are separated by valves that open and close to direct blood flow through the heart. Blood is pumped through the body delivering oxygen and nutrients to all parts of the body. The blood then returns to the right side of the heart. From there, the blood is pumped to the lungs where it is receives a fresh supply of oxygen. The left side of the heart receives this blood from the lungs and pumps it through arteries to your heart muscle and other parts of your body. This happens thousands of times a day.
The right atrium and right ventricle pump deoxygenated blood from the body to the lungs via the pulmonary artery. Carbon dioxide is then exchanged for oxygen in the capillaries of the lungs. The oxygenated blood then travels from the lungs, via the pulmonary vein to the left atrium and left ventricle, and then is pumped to the rest of the body to feed the cells.Answer 2:The heart is a four-chambered muscular organ that pumps blood to all parts of the body. A wall, called a septum, divides the heart into a right and left side. Each side is further divided in to an upper chamber (called the atrium) and a lower chamber (called the ventricle). These chambers are separated by valves that open and close to direct blood flow through the heart. Blood is pumped through the body delivering oxygen and nutrients to all parts of the body. The blood then returns to the right side of the heart. From there, the blood is pumped to the lungs where it is receives a fresh supply of oxygen. The left side of the heart receives this blood from the lungs and pumps it through arteries to your heart muscle and other parts of your body. This happens thousands of times a day.
These "doors" are the following valves:Tricuspid Valve - arterioventricular valve of the right sidePulmonary Semilunar Valve - right side of the heartMitral or Bicuspid Valve - AV valve of the left sideAortic Semilunar Valve - left side of the heart
The heart valves open when blood is flowing through. They close to prevent backflow.
The blood passes through tiny capillaries that lie in close proximity to the alveoli in the lungs. This is where the gas exchange takes place.