The sinoatrial node, SA node is called the heart's natural pacemaker that causes the atria to contract when the electrical impulse is released. The signal is then passed on to the atrioventricular node, AV node, and then to the conduction pathways bundle of His to provide electrical stimulus to the ventricles. Dr Michael Rowe is an Interventional Cardiologist with special interest in coronary angiography, balloon Normal Heart Anatomy The main function of the heart is to deliver oxygen-rich blood to every cell in the body.
To understand the anatomy and function of the heart, we have divided the heart into two sections - Exterior and Interior Exterior Anatomy Vena Cava The vena cava is a large vein that brings deoxygenated impure blood back to the heart and empties it in to the right atriuma.
Atria There are two atria, the right atrium, and the left atrium, which are the two upper chambers of the four muscular chambers of the heart.
Ventricles There are two ventricles, right and left, which are the two lower chambers of the four muscular chambers of the heart. Pulmonary Artery As part of the pulmonary circulation, the pulmonary artery carries the de-oxygenated blood from the right ventricle to the lungs for oxygenation.
Pulmonary Veins Blood after oxygenation in the lungs, is brought back to the heart by pulmonary veins and delivered to left atrium. Aorta 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. Pericardium The pericardium is the fluid filled sac that surrounds the heart.
The main function of the pericardium is to: Keep the heart within the chest cavity Act as a shock absorber preventing the heart from over expanding when blood volume increases Coronary Circulation The coronary circulation consists of the blood vessels that supply blood to, and remove blood from, the heart tissue.
Serious heart damage may occur when the coronary circulation is blocked. Coronary Arteriesy Blood is supplied to the heart by the coronary arteries. Coronary Veins The deoxygenated blood from the heart muscle is collected by the coronary veins and drained into the right atrium. Circulatory system 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. The pulmonary valve also called the pulmonic valve , which also has three cusps, separates the right ventricle from the pulmonary artery.
Similar to the aortic valve, the pulmonary valve opens in ventricular systole, when the pressure in the right ventricle exceeds the pressure in the pulmonary artery. When ventricular systole ends, pressure in the right ventricle drops rapidly, and the pressure in the pulmonary artery forces the pulmonary valve to close.
The closure of the pulmonary valve also produces a sound, however it is softer than the aortic sound because the blood pressure in the right side of the heart is lower compared to the left side, due to the differences between pulmonary and systemic circulation.
Valves are vulnerable to several conditions that impair their normal functions. Two of the most common problems with the semilunar valves are stenosis and regurgitation.
Valve stenosis refers to narrowing of the valves, which prevents the valve from opening fully, causing an obstruction of blood flow.
Valve stenosis is often caused by calcium buildup and scarring from rheumatic fever, and may cause cardiac hypertrophy and heart failure. Valve regurgitation is backflow through the valves that occurs when when they cannot close completely. From the right atrium, the blood will travel through the pulmonary circulation to be oxygenated before returning gain to the system circulation, completing the cycle of circulation through the body.
The arterial component of systemic circulation the highest blood pressures in the body. The venous component of systemic circulation has considerably lower blood pressure in comparison, due to their distance from the heart, but contain semi-lunar valves to compensate.
Systemic circulation as a whole is a higher pressure system than pulmonary circulation simply because systemic circulation must force greater volumes of blood farther through the body compared to pulmonary circulation. Privacy Policy. Skip to main content. Cardiovascular System: The Heart. Search for:. Circulation and Heart Valves.
Heart Circulation Coronary circulation is the circulation of blood in the blood vessels of the heart. Learning Objectives Describe circulation of blood in the heart. Key Takeaways Key Points The vessels that supply blood to the myocardium are called coronary arteries and coronary veins. The left and right coronary arteries branch off into smaller arteries, such as the important left anterior descending LAD coronary artery.
Most tissue perfusion in the heart occurs when the coronary arteries open during diastole. Failure of the coronary arteries to provide sufficient blood supply to the heart can lead to ischemia, angina, and myocardial infarction. Norepinephrine will cause vasodilation in the coronary arteries but vasoconstriction in the other arteries of the body. Myocardial infarctions are the result of ruptured artherosclerotic plaques or arterial thrombosis, which cause the death of heart tissue from prolonged ischemia.
Key Terms myocardial infarction : Necrosis of heart muscle caused by an interruption to the supply of blood to the heart, often as a result of prolonged ischemia. It may be either transient unstable or stable, and stable anginas typically lead to infarction. Examples Atherosclerotic plaques in a coronary artery will slowly occlude block the vessel.
Operation of Atrioventricular Valves The atrioventricular valves separate the atria from the ventricles and prevent backflow from the ventricles into the atria during systole. Learning Objectives Describe the operation of the atrioventricular valves: bicuspid mitral and tricuspid. Key Takeaways Key Points The atrioventricular valves, the bicuspid mitral and tricuspid valves, separate the atria from the ventricles.
The bicuspid valve is on the left side of the heart and the tricuspid valve is on the right side of the heart. Blood flows through an atrioventricular AV valve when blood pressure in the atria becomes high during atrial systole and blood pressure in the ventricles becomes low enough during ventricular diastole, creating a blood pressure gradient.
Papillary muscles, finger-like projections from the wall of the ventricles, connect the chordae tendineae heartstrings to the cusps of the atrioventricular valves. This connection prevents the valve from prolapsing under pressure. Papillary muscles, together with the chordae tendineae, make up the subvalvular apparatus.
Key Terms Atrioventricular valves : These valves separate the atria from the ventricles on each side of the heart and prevent backflow from the ventricles into the atria during systole. They include the mitral and tricuspid valves. Subvalvular apparatus : The papillary muscles and the chordae tendineae, known as the subvalvular apparatus, hold the valves closed so that they do not prolapse.
Operation of Semilunar Valves The semilunar valves allow blood to be pumped into the major arteries while preventing backflow of blood from the arteries into the ventricles. Learning Objectives Describe the operation of the semilunar valves. Key Takeaways Key Points The semilunar valves act to prevent backflow of blood from the arteries to the ventricles during ventricular diastole and help maintain pressure on the major arteries.
The aortic semilunar valve separates the left ventricle from the opening of the aorta. The aortic and pulmonary valves are semilunar valves which separate the ventricles from the aorta and pulmonary artery, respectively. Partial pressure gradient changes during systole and diastole cause the opening and closing of the valves.
Right ventricle: Receives blood from the right atrium; pumps blood into the pulmonary artery. Pulmonary valve: Allows blood to pass into the pulmonary arteries; prevents blood from flowing back into the right ventricle. Pulmonary veins: Deliver oxygen-rich blood from the lungs to the left atrium of the heart. Mitral valve: Allows blood to flow into the left ventricle; prevents blood from flowing back into the left atrium.
Left ventricle: Receives oxygen-rich blood from the left atrium and pumps blood into the aorta. Aortic valve: Allows blood to pass from the left ventricle to the aorta; prevents backflow of blood into the left ventricle. Breadcrumb Home Medical services Heart and vascular care Your cardiovascular health How the heart works How the heart works.
Valves maintain direction of blood flow As the heart pumps blood, a series of valves open and close tightly. The tricuspid valve is situated between the right atrium and right ventricle. The pulmonary valve is between the right ventricle and the pulmonary artery. The mitral valve is between the left atrium and left ventricle. The aortic valve is between the left ventricle and the aorta.
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