explain working of heart
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The Working Heart
Heart & Vascular
The heart is a muscular organ that pumps blood continuously throughout the body. It is comprised of four chambers — the right and left atrium and the right and left ventricle.
The chambers of the heart work together by alternately contracting and relaxing to pump blood throughout the heart. To accomplish this, the heart uses an electrical system to trigger a heartbeat. Essentially, the electrical system is the power source that makes all the heart's functions possible.
Blood vessels lead in and out of the chambers, which receive and distribute blood throughout the body. The four chambers are connected by four valves — the tricuspid, pulmonic, mitral and aortic valves. These valves work like one-way doors, allowing blood to flow in only one direction.
Blood Circulation
As the heart beats, it pumps blood through a system of blood vessels called the circulatory system. The blood that these vessels carry is essential for the body to function. Blood carries oxygen and nutrients to your body's tissues, assists in the removal of carbon dioxide and waste products and promotes the overall health of the body's tissues. There are three main types of vessels that make up this system:
Arteries
Veins
Capillaries
Arteries carry oxygen-rich blood away from the heart to the body's tissues. Veins take oxygen-poor blood back to the heart. Capillaries are small thin blood vessels that connect the arteries and the veins.
How blood flow works
Blood enters the heart through two large veins, the inferior and superior vena cava, emptying into the right atrium. It flows from the right atrium through the tricuspid valve into the right ventricle. The blood then leaves the right ventricle and heart through the pulmonic valve and flows into the pulmonary artery and to the lungs. Oxygenated blood returns from the lungs to the heart via the pulmonary vein into the left atrium. From the left atrium, blood flows through the mitral valve to the left ventricle. From the left ventricle blood leaves the heart through the aortic valve and flows into the aorta and to the body.
Coronary Arteries
The heart muscle needs its own supply of oxygen and nutrients to pump properly. Although its chambers are full of blood, the heart receives no nourishment from this blood. The heart receives its own supply of blood through a network of arteries known as the coronary arteries.
Functions of right and left coronary arteries
The coronary arteries wrap around the surface of the heart. The two main coronary arteries, the right coronary artery and the left coronary artery, branch off from the aorta. The right coronary artery supplies the right atrium and right ventricle. It branches into the posterior descending artery. The left coronary artery branches into the circumflex artery and the left anterior descending artery. The left coronary artery supplies the left atrium and the left ventricle.
Narrow coronary arteries
Collateral circulation is a network of tiny blood vessels that usually remain inactive. When coronary arteries narrow to the point that blood flow to the heart is limited, collateral vessels become enlarged and active. This process allows for blood flow around the blocked artery to the heart muscle.
The right atrium receives oxygen-poor blood from the body and pumps it to the right ventricle through the tricuspid valve.
The right ventricle pumps the oxygen-poor blood to the lungs through the pulmonary valve.
The left atrium receives oxygen-rich blood from the lungs and pumps it to the left ventricle through the mitral valve.
The left ventricle pumps the oxygen-rich blood through the aortic valve out to the rest of the body.
The left and right atria are smaller chambers that pump blood into the ventricles. The left and right ventricles are stronger pumps. The left ventricle is the strongest because it has to pump blood out to the entire body. When your heart functions normally, all four chambers work together in a continuous and coordinated effort to keep oxygen-rich blood circulating throughout your body. Your heart has its own electrical system that coordinates the work of the heart chambers (heart rhythm) and also controls the frequency of beats (heart rate).