The heart is a muscle that works to provide oxygen and nutrients to both the lungs and the body system while removing carbon dioxide and waste products.
The heart consists of:
External walls
Blood filled chambers
Valves which allow blood to flow through the chambers
Blood vessels that carry blood to the other structures
Electrical signaling conduction system
The three walls of heart are:
Endocardium; innermost layer
Myocardium: muscular middle layer
Epicardium: outermost layer
Chambers of heart:
Right atrium
Right ventricle
Left atrium
Left ventricle
Valves of heart:
Atrioventricular valves:
Tricuspid valve: lies between right atrium and right ventricle
Mitral valve: lies between left atrium and left ventricle
Semilunar valves:
Aortic valve: oxygenated blood flows from left ventricle to aorta
Pulmonary valve: de-oxygenated blood
Blood vessels:
Arteries: carry oxygenated blood
Veins: carry de-oxygenated blood
Capillaries: small blood vessels for exchange of de-oxygenated and oxygenated blood
Major coronary arteries:
Left coronary artery: divides into circumflex artery and left anterior descending artery
Circumflex artery: supplies blood to the left atrium and back of left ventricle
Left anterior descending artery: supplies blood to the font and bottom of the left ventricle
Right coronary artery: supplies blood to the right atrium, right ventricle, bottom portion of left ventricle
The heart is separated into four chambers that work to ensure blood flow occurs in the right direction. The left and right side of the heart work separately to ensure blood reaches either the lungs or body system. The left side of the heart pumps blood directly to the lungs providing oxygen to the blood while the right side of heart receives blood that has been pumped throughout the entire body and is deoxygenated.
Deoxygenated blood returns to the heart
Blood lacking oxygen returns from the body to the heart through two large veins:
Superior vena cava: brings blood from the upper body.
Inferior vena cava: brings blood from the lower body.
Right atrium
The deoxygenated blood enters the right atrium, the heart’s upper right chamber.
Right ventricle
Blood flows from the right atrium into the right ventricle, the lower right chamber.
Pulmonary arteries to the lungs
The right ventricle pumps the blood through the pulmonary arteries to the lungs. *(Note: Despite being called arteries, these carry deoxygenated blood.)
Lungs oxygenate the blood
In the lungs, carbon dioxide is exchanged for oxygen. The now oxygen-rich blood is ready to return to the heart.
Left atrium
Oxygenated blood returns to the heart via the pulmonary veins into the left atrium, the upper left chamber.
Left ventricle
Blood moves from the left atrium into the left ventricle, the lower left chamber.
Aorta to the body
The left ventricle pumps the oxygen-rich blood into the aorta, the body’s main artery, which distributes it throughout the body.
Electrical signals within the heart act as a pacemaker to the heart by assisting with controlling heart rate, coordinating the heart chambers (atria and ventricles), adapt to the changing needs to the body, and ensure appropriate circulation.
The amount of blood pumped with each heart beat is crucial to maintaining vitality of the lungs and peripheral system. The principles that are important in this process are afterload and preload. If there is dysfunction in either of these components, then the individual may experience stroke, myocardial infarction, or death.
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