Blood starts in the left atrium, passes through what part and finally returns to the left atrium?
The blood circulation is divided into body circulation and pulmonary circulation
Pulmonary circulation: right ventricle – pulmonary artery – capillary network in the lungs – pulmonary veins – left atrium
Body circulation: left ventricle – aorta – capillary network in all parts of the body – upper and lower vena cava – right atrium
Blood circulation route: left ventricle → (arterial blood at this time) → aorta → all levels of arteries → capillaries (material exchange) → (material exchange and become venous blood) → all levels of veins → upper and lower vena cava → right atrium → right ventricle → pulmonary artery → pulmonary capillaries (material exchange) → (material exchange and become arterial blood) → pulmonary veins → left atrium → finally back to the left ventricle, starting a new round of circulation.
What are the two periods of ventricular systole?
The isovolumic systolic period and the rapid and slowing ejection period.
(1) During isovolumic systole, the ventricle begins to contract, the intraventricular pressure is still lower than the aortic pressure, the semilunar disc is still closed, and the ventricle becomes a closed cavity. Although the ventricle contracts, the ventricular volume does not change, so it is called the isovolumic systolic period, about 0.05s.
(2) When the intraventricular pressure rises above the aortic pressure during isovolumic systole, the semilunar valve is flushed open and the isovolumic systole ends, entering the ejection phase. During the first 1/3 of the ejection phase, the volume of blood injected from the ventricle into the aorta is large (about 2/3 of the output per beat), and the flow rate is also rapid.
Subsequently, the intraventricular pressure begins to decline and the ejection velocity gradually slows down, which is called the slow ejection period. At this time, although the intraventricular pressure is slightly lower than the aortic pressure, the blood has greater kinetic energy and continues to flow into the aorta against the pressure gradient according to its inertia, and the ventricular volume continues to shrink. This period is 0.15 s.
What two periods are included in ventricular diastole?
It includes the isovolumic diastolic period and the rapid and slow filling period.
(1) Isovolumic diastole
After the ventricular myocardium starts diastole, the intraventricular pressure decreases, and the blood in the aorta flows back toward the ventricle, pushing the semilunar valve to close; at this time, the intraventricular pressure is still higher than the intraatrial pressure, and the atrioventricular valve is still in the closed state, and the ventricle becomes a closed chamber again. The ventricular muscle diastolic, intraventricular pressure decreases sharply and rapidly, but the volume does not change. From the time the semilunar valve closes until the intraventricular pressure falls below the intraatrial pressure, the atrioventricular valve opens, this period is called the isovolumic diastolic period, lasting about 0.06-0.08s
(2) Filling phase
When the ventricular pressure drops below the intraatrial pressure, the atrioventricular valve opens and ventricular filling begins, and blood flows rapidly into the ventricle along the atrial-ventricular pressure gradient, which is called the rapid filling period, lasting about 0.11s. Then, blood continues to flow into the ventricle at a higher rate, and the ventricular volume increases further, called the slow filling period, which lasts about 0.22 s. Then the next cardiac cycle begins.
Heart valve auscultation area?
Mitral valve zone: the apical region, located at the 5th intercostal space medial to the left midclavicular line.
Aortic valve area: there are two auscultation areas, the second intercostal area at the right edge of the sternum and the third and fourth intercostal areas at the left edge of the sternum, the latter being the second auscultation area.
Pulmonary valve area: at the second intercostal space on the left edge of the sternum.
Tricuspid valve area: at the lower end of the sternal body near the saber slightly to the right or slightly to the left.