aortic valve is the valve responsible for preventing backflow of blood from the lungs into the heart.
aortic valve is the valve responsible for preventing backflow of blood from the lungs into the heart.
valve responsible for preventing backflow of blood from the lungs into the heart?
aortic valve
the first heart sound, or s, forms the "lub" of "lub-dub" and is composed of components m (mitral valve closure) and t (tricuspid valve closure). normally m precedes t slightly. it is caused by the closure of the atrioventricular valves, i.e. tricuspid and mitral (bicuspid), at the beginning of ventricular contraction, or systole. when the ventricles begin to contract, so do the papillary muscles in each ventricle. the papillary muscles are attached to the cusps or leaflets of the tricuspid and mitral valves via chordae tendineae (heart strings). when the papillary muscles contract, the chordae tendineae become tense and thereby prevent the backflow of blood into the lower pressure environment of the atria. the chordae tendineae act a bit like the strings on a parachute, and allow the leaflets of the valve to balloon up into the atria slightly, but not so much as to evert the cusp edges and allow back flow of blood. it is the pressure created from ventricular contraction that closes the valve, not the papillary muscles themselves. the contraction of the ventricle begins just prior to av valves closing and prior to the semilunar valves opening. the sudden tensing of the chordae tendineae and the squeezing of the ventricles against closed semilunar valves, sends blood rushing back toward the atria, and the parachute-like valves catch the rush of blood in their leaflets causing the valve to snap shut. the s1 sound results from reverberation within the blood associated with the sudden block of flow reversal by the valves. the delay of t1 even more than normally causes the split s1 which is heard in a right bundle branch blockage.
heart sounds
the mammalian heart has four chambers, two upper atria, the receiving chambers, and two lower ventricles, the discharging chambers. the heart has four valves, which separate its chambers and ensures blood flows in the correct direction through the heart (preventing backflow). after gas exchange in the pulmonary capillaries (blood vessels in the lungs), oxygen-rich blood returns to the left atrium via one of the four pulmonary veins. blood flows nearly continuously back into the atrium, which acts as the receiving chamber, and from here through an opening into the left ventricle. most blood flows passively into the heart while both the atria and ventricles are relaxed, but toward the end of the ventricular relaxation period, the left atrium will contract, pumping blood into the ventricle. the heart also requires nutrients and oxygen found in blood like other muscles, and is supplied via coronary arteries.
mammal