The endocardium can become infected, a serious inflammatory condition called infective endocarditis. This and other potential problems with the endocardium may damage the valves and impair the normal flow of blood through the heart. The heart has four chambers. The two atria receive blood into the heart and the two ventricles pump blood into circulation.
The heart is the complex pump of the circulatory system, pumping blood throughout the body for the purposes of tissue oxygenation and gas exchange. The heart has four chambers through which blood flows: two sets of each type of chamber atria and ventricles , one per side, each with distinct functions.
The left side of the heart deals with systemic circulation while the right side of the heart deals with pulmonary circulation. The atria are chambers in which blood enters the heart. They are located on the anterior end of the heart, with one atrium on each side. The right atrium receives deoxygenated blood from systemic circulation through the superior vena cava and inferior venae cavae. The left atrium receives oxygenated blood from pulmonary circulation through the left and right pulmonary veins.
Blood passively flows into the atria without passing through valves. The atria relax and dilate expand while they fill with blood in a process called atrial diastole. The atria and ventricles are separated by the mitral and tricuspid valves. The atria undergo atrial systole, a brief contraction of the atria that ejects blood from the atria through the valves and into the ventricles.
The chordae tendinae are elastic tendons that attach to the valve from the ventricles and relax during atrial systole and ventricular diastole, but contract and close off the valve during ventricular systole. One of the defining characteristics of the atria is that they do not impede venous flow into the heart.
Atria have four essential characteristics that cause them to promote continuous venous flow:. The ventricles are located on the posterior end of the heart beneath their corresponding atrium.
The right ventricle receives deoxygenated blood from the right atria and pumps it through the pulmonary vein and into pulmonary circulation, which goes into the lungs for gas exchange. The left ventricle receives oxygenated blood from the left atria and pumps it through the aorta into systemic circulation to supply the tissues of the body with oxygen. The walls of the ventricles are thicker and stronger than those of the atria.
The physiologic load on the ventricles, which pump blood throughout the body and lungs, is much greater than the pressure generated by the atria to fill the ventricles. Further, the left ventricle has thicker walls than the right because it pumps blood throughout the body, while the right ventricle pumps only to the lungs, which is a much smaller volume of blood.
During ventricular diastole, the ventricles relax and fill with blood. During ventricular systole, the ventricles contract, pumping blood through the semi-lunar valves into systemic circulation. Structure of the heart : Structure diagram of a coronal section of the human heart from an anterior view. The two larger chambers are the ventricles.
The human circulatory system is a double system, meaning there are two separate systems of blood flow: pulmonary circulation and systemic circulation. The adult human heart consists of two separated pumps, the right side right atrium and ventricle, which pumps deoxygenated blood into the pulmonary circulation, and the left side left atrium and ventricle , which pumps oxygenated blood into the systemic circulation.
Great vessels are the major vessels that carry blood into the heart and away from the heart to and from the pulmonary or systemic circuit.
The great vessels collect and distribute blood across the body from numerous smaller vessels. The Systemic Circuit : The venae cavae and the aorta form the systemic circuit, which circulates blood to the head, extremities and abdomen. The superior and inferior vena cava are collectively called the venae cavae. The venae cavae, along with the aorta, are the great vessels involved in systemic circulation.
These veins return deoxygenated blood from the body into the heart, emptying it into the right atrium. The venae cavae are not separated from the right atrium by valves. The superior vena cava is a large, short vein that carries deoxygenated blood from the upper half of the body to the right atrium. The right and left subclavian veins, jugular veins, and thyroid veins feed into the superior vena cava. The subclavian veins are significant because the thoracic lymphatic duct drains lymph fluid into the subclavian veins, making the superior vena cava a site of lymph fluid recirculation into the plasma.
The superior vena cava begins above the heart. The inferior vena cava is the largest vein in the body and carries deoxygenated blood from the lower half of the body into the heart. The left and right common iliac veins converge to form the inferior vena cava at its lowest point.
The inferior vena cava begins posterior to the abdominal cavity and travels to the heart next to the abdominal aorta. Along the way up the body from the iliac veins, the renal and suprarenal veins kidney and adrenal glands , lumbar veins from the back , and hepatic veins from the liver all drain into the inferior vena cava.
The aorta is the largest of the arteries in systemic circulation. Blood is pumped from the left ventricle through the aortic valve into the aorta. The aorta is a highly elastic artery and is able to dilate and constrict in response to blood pressure and volume. When the left ventricle contracts to force blood through the aortic valve into the aorta, the aorta expands. This expansion provides potential energy to help maintain blood pressure during diastole, when the aorta passively contracts.
Blood pressure is highest in the aorta and diminishes through circulation, reaching its lowest points at the end of venous circulation. The difference in pressure between the aorta and right atrium accounts for blood flow in the circulation, as blood flows from areas of high pressure to areas of low pressure. The aortic arch contains peripheral baroreceptors pressure sensors and chemoreceptors chemical sensors that relay information concerning blood pressure, blood pH, and carbon dioxide levels to the medulla oblongata of the brain.
This information is processed by the brain and the autonomic nervous system mediates the homeostatic responses that involve feedback in the lungs and kidneys.
The aorta extends around the heart and travels downward, diverging into the iliac arteries. The five components of the aorta are:. The pulmonary arteries carry deoxygenated blood from the right ventricle into the alveolar capillaries of the lungs to unload carbon dioxide and take up oxygen.
These are the only arteries that carry deoxygenated blood, and are considered arteries because they carry blood away from the heart. The short, wide vessel branches into the left and right pulmonary arteries that deliver deoxygenated blood to the respective lungs. Blood first passes through the pulmonary valve as it is ejected into the pulmonary arteries.
Pulmonary circuit : Diagram of pulmonary circulation. Oxygen-rich blood is shown in red; oxygen-depleted blood in blue. The pulmonary veins carry oxygenated blood from the lungs to the left atrium of the heart.
Despite carrying oxygenated blood, this great vessel is still considered a vein because it carries blood towards the heart. An electrical system that stimulates contraction of the heart muscle. Search Encyclopedia. About the Heart and Blood Vessels The heart is the hardest working muscle in the human body. How the heart works The heart is a large, muscular organ that pumps blood filled with oxygen and nutrients through the blood vessels to the body tissues.
It's made up of: 4 chambers. Here is the process: The right atrium receives blood from the body. The left atrium receives blood from the lungs. This blood is rich in oxygen. These bring blood to the lungs, where oxygen enters the bloodstream, and then to the body: The inferior and superior vena cava bring oxygen-poor blood from the body into the right atrium. The pulmonary veins bring oxygen-rich blood to the left atrium.
The right pulmonary veins pass behind the right atrium and superior vena cava while the left pass in front of the descending thoracic aorta. The pulmonary arteries and veins are both considered part of pulmonary circulation. Learning Objectives Describe the great vessels that carry blood to and from the heart. Key Points Five great vessels enter and leave the heart: the superior and inferior vena cava, the pulmonary artery, the pulmonary vein, and the aorta. The superior vena cava and inferior vena cava are veins that return deoxygenated blood from circulation in the body and empty it into the right atrium.
The pulmonary artery carries deoxygenated blood from the right ventricle into the lungs for oxygenation. The pulmonary veins carry oxygenated blood from the lungs into the left atrium where it is returned to systemic circulation. The aorta is the largest artery in the body. It carries oxygenated blood from the left ventricle of the heart into systemic circulation. The aorta has many subdivisions that branch off into smaller arteries.
These subdivisions are the ascending and descending aorta, the aortic arch, and the thoracic and abdominal aorta. Key Terms pulmonary arteries : The arteries that take deoxygenated blood away from the right side of the heart and into the capillaries of the lungs for the purpose of gas exchange. The Venae Cavae The Systemic Circuit : The venae cavae and the aorta form the systemic circuit, which circulates blood to the head, extremities and abdomen.
Superior Vena Cava The superior vena cava is a large, short vein that carries deoxygenated blood from the upper half of the body to the right atrium. Inferior Vena Cava The inferior vena cava is the largest vein in the body and carries deoxygenated blood from the lower half of the body into the heart. The Aorta The aorta is the largest of the arteries in systemic circulation.
Learn why this happens, as well as other causes of white patches on your tongue. The location, hardness, and other characteristics of a pea-sized lump may determine whether the cause is temporary or if you should see the doctor…. Clubbing of your fingers or toes occurs when your nails become wider and rounder. Learn about conditions that can cause it, such as lung cancer. Health Conditions Discover Plan Connect. Artery vs. Medically reviewed by Gerhard Whitworth, R.
These systems of tubes are either: Pulmonary. What are the different types of arteries? What are the different types of veins? Artery and vein diagram.
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