Separates the right ventricle from the pulmonary artery. Opens to allow blood to be pumped from the right ventricle to the lungs through the pulmonary artery where it will receive oxygen. Prevents the back flow of blood from the pulmonary artery to the right ventricle.
Related valve problems include: pulmonary valve stenosis , pulmonary valve regurgitation Mitral Valve Has two leaflets. Separates the top left chamber left atrium from the bottom left chamber left ventricle. Opens to allow blood to flow from the left atrium to the left ventricle. Prevents the back flow of blood from the left ventricle to the left atrium.
Related valve problems include: mitral valve prolapse , mitral valve regurgitation , mitral valve stenosis Aortic Valve Has three leaflets, unless it's abnormal from birth, i. Separates the left ventricle from the aorta. Opens to allow blood to leave the heart from the left ventricle through the aorta and the body.
The blood supply to the heart is greater than that of other body tissues since the heart has a constant metabolic demand that must be satisfied to keep the heart pumping at all times.
Coronary Circulation : Coronary arteries labeled in red text and other landmarks in blue text. The coronary arteries originate from the left side of the heart descending from the aorta. There are multiple coronary arteries derived from the larger right and left coronary arteries. For example, important coronary arteries that branch off from the larger arteries include the left anterior descending LAD coronary and the right posterior coronary.
Coronary arteries run both along the surface of the heart and deep within the myocardium, which has the greatest metabolic demands of all the heart tissues due to its muscle content. Epicardial coronary arteries, which run along on the surface of the heart, are capable of autoregulating vasodilation and vasoconstriction to maintain coronary blood flow at appropriate levels to fit the metabolic demands of the heart muscle. These vessels are relatively narrow and thus vulnerable to blockage, which may cause a myocardial infarction.
Subendocardial coronary arteries run deep within the myocardium to provide oxygen throughout the muscle tissue of the cardiac wall. In systole, the ventricular myocardium contracts, generating high intraventricular pressure and compressing the subendocardial coronary vessels while allowing the epicardial coronary vessels to remain fully open.
With the subendocardial coronary vessels compressed, blood flow essentially stops below the surface of the myocardium. In diastole, the ventricular myocardium contracts, lowering the intraventricular pressure and allowing the subendocardial vessels to become open again.
Due to the high pressures generated in the ventricular myocardium during systole, most myocardial tissue perfusion occurs during diastole.
Additionally, catecholamines such as norephinephrine, which normally cause vasoconstriction will instead cause vasodilation within the coronary arteries. This mechanism is due to beta-adrenergic receptors in the coronary arteries and helps enable the increased cardiac output associated with fight-or-flight responses.
A myocardial infarction heart attack may be caused by prolonged ischemia oxygen deprivation in the heart, which occurs due to blockage of any of the coronary arteries. Since there is very little unnecessary blood supply to the myocardium, blockage of these vessels can cause serious damage. When these vessels become blocked, the myocardium becomes oxygen-deprived, a condition called ischemia. Brief periods of ischemia in the heart are associated with intense chest pain called angina, which may either be transient if the clot breaks up on its own or stable if it does not.
As the time period of ischemia increases, the hypoxic conditions cause muscle tissue to die, causing a myocardial infarction heart attack. Myocardial infarction is one of the most common causes of death worldwide.
The clots that cause the infarction are usually the result of ruptured atherosclerotic plaques that break off and occlude the coronary arteries, but arterial thrombosis from injury or pooled blood may also cause a heart attack. The tissues of the heart do not regenerate, so those that survive a myocardial infarction will generally have scar tissue in their myocardium and may be more susceptible to other heart problems in the future.
The atrioventricular valves separate the atria from the ventricles and prevent backflow from the ventricles into the atria during systole. A heart valve allows blood flow in only one direction through the heart, and the combination of the atrioventricular and semi-lunar heart valves determines the pathway of blood flow.
Valves open or close based on pressure differences across the valve. The atrioventricular AV valves separate the atria from the ventricles on each side of the heart and prevent backflow of blood from the ventricles into the atria during systole. Cross section of heart indicating heart valves : The four valves determine the pathway of blood flow indicated by arrows through the heart.
The subvalvular apparatus describes the structures beneath the AV valves that prevent the valves prom prolapsing. Valve prolapse means that the valves do not close properly, which may cause regurgitation or backflow of blood from the ventricle back into the atria, which is inefficient.
The subvalvular apparatus includes the chordae tendineae and the papillary muscles. The AV valves are anchored to the wall of the ventricle by chordae tendineae heartstrings , small tendons that prevent backflow by stopping the valve leaflets from inverting. The chordae tendineae are inelastic and attached at one end to the papillary muscles and at the other end to the valve cusps.
Papillary muscles are finger-like projections from the wall of the ventricle that anchor the chordae tendineae. This connection provides tension to hold the valves in place and prevent them from prolapsing into the atria when they close, preventing the risk of regurgitation.
The subvalvular apparatus has no effect on the opening and closing of the valves, which is caused entirely by the pressure gradient of blood across the valve as blood flows from high pressure to low pressure areas. The mitral valve is on the left side of the heart and allows the blood to flow from the left atrium into the left ventricle. Each heart valve, except for the mitral valve, has three flaps leaflets that open and close like gates on a fence.
The mitral valve has two valve leaflets. While the heart and lungs are the largest organs of the circulatory system, the blood vessels are the longest. This extended network of stretchy tubes circulates blood throughout the body. Laid end-to-end, your body's blood vessels would extend about 60, miles. That's more than 21 road trips between New York and Los Angeles! Arteries along with smaller arterioles and microscopic capillaries convey oxygen- and nutrient-rich blood to the body's tissues.
In turn, veins bring nutrient-depleted blood back to the heart. Along the way, blood is routed through the kidneys and liver, as well, filtering waste products from the blood. The heart's four chambers pump in an organized manner with the help of electrical impulses that originate in the sinoatrial node also called the "SA node".
Situated on the wall of the right atrium, this small cluster of specialized cells is the heart's natural pacemaker, initiating electrical impulses at a normal rate. The impulse spreads through the walls of the right and left atria, causing them to contract, forcing blood into the ventricles. This delivery is regulated by the pulmonary valve.
The left ventricle collects the pure blood from the left atrium and delivers it to the aorta main artery from where it is pumped to the rest of the body. This delivery is regulated by the aortic valve. As part of the pulmonary circulation, the pulmonary artery carries the de-oxygenated blood from the right ventricle to the lungs for oxygenation.
Blood after oxygenation in the lungs, is brought back to the heart by pulmonary veins and delivered to left atrium. The Aorta the largest artery in the body, collects blood pumped from the left ventricle to branch and deliver the oxygen rich blood to various organs and tissues in the human body. The pericardium is the fluid filled sac that surrounds the heart. The heart literally floats in this pericardial fluid. The coronary circulation consists of the blood vessels that supply blood to, and remove blood from, the heart tissue.
Coronary arteries supply oxygen rich blood to the heart and the coronary veins remove the deoxygenated blood from the heart. Blood is supplied to the heart by the coronary arteries. Two main coronary arteries branch off the aorta then branch into several smaller arteries that supply oxygen rich blood to the heart. The deoxygenated blood from the heart muscle is collected by the coronary veins and drained into the right atrium.
The heart acts a pump, delivering blood to the organs, tissues, and cells of your body through a complex network of arteries, arterioles, and capillaries. Blood is returned to your heart through venules small veins and veins.
The heart rate is controlled by the brain and varies depending on, factors such as age, stress, exercise, surrounding temperature, and hormones.
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