The Circulatory System Essay -- essays research papers

The Circulatory SystemThe circulatory system in anatomy and physiology is the course taken bythe declination through the arteries, capillaries, and veins and sustain to the heart. In world and the higher vertebrates, the heart is made up of four chambers the castigate and left auricles, or atria, and the right and left ventricles. The rightside of the heart pumps oxygen-poor riptide from the cells of the body back to thelungs for new oxygen the left side of the heart receives fund rich in oxygenfrom the lungs and pumps it through the arteries to the various parts of thebody. Circulation begins previous(predicate) in fetal life. It is estimated that a givenportion of the product line completes its course of circulation in approximately 30seconds.Pulmonary circulation is where the blood from the entire body istransported to the right auricle through two large veins. The superior vena cavaand the inferior vena cava. When the right auricle contracts, it forces theblood through an opening into the right ventricle. condensing of this ventricledrives the blood to the lungs. Blood is prevented from returning into theauricle by the tricuspid valve, which completely closes during condensate ofthe ventricle. In its passage through the lungs, the blood is oxygenated, thatis, then it is brought back to the heart by the four pulmonary veins, whichenter the left auricle. When this chamber contracts, blood is forced into theleft ventricle and then by ventricular contraction into the aorta. The bicuspid,or mitral, valve prevents the blood from flowing back into the auricle, and thesemilunar valves at the beginning of the aorta stop it from flowing back intothe ventricle. Similar valves are present in the pulmonary artery.The aorta break opens into a number of main branches, which in turn divideinto smaller ones until the entire body is supplied by an elaborately branchingseries of blood vessels. The smallest arteries divide into a fine network ofstill more minute vess els, the capillaries, which have extremely thin wallsthus, the blood is enabled to come into close relation with the fluids andtissues of the body. In the capillaries, the blood performs three functions thenit releases its oxygen to the tissues, it furnishes to the body cells thenutrients and other essential substances that... ...itiating the heartbeat. The contraction then spreads over the auricles inthe septum between the auricles, it excites another node called the atrioventricular node. The auriculoventricular bundle conducts the impulsefrom this node to the muscles of the ventricles, and in this way contraction andrelaxation of the heart are coordinated. Each phase of the cardiac cycle isassociated with the production of an electrical potential that nookie be recordedby electrical instruments to produce a reading known as an electrocardiogram.Circulation of the blood in superficial capillaries can be observedunder the microscope. The red blood cells can be seen moving along rapidly inthe middle of the blood current, while the egg white cells advance more slowly alongthe walls of the capillaries. The capillaries present a far larger surface withwhich the blood comes in contact than do other blood vessels end because theyconsequently offer the greatest resistance to the progress of the blood, theyhave a great influence on the circulation. Capillaries expand when temperaturerises and help to cool the blood then they contract in cold and help preserveinternal heat.