SCIENCE
CIRCULATORY SYSTEM
|
Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
|
|
|
the ventricles are relaxed and the atria contracted
|
|
|
the ventricles and the atria are relaxed
|
|
|
the ventricles and the atria are contracted
|
|
|
the ventricles are contracted and the atria are relaxed
|
Detailed explanation-1: -Ventricular systole: lasts about 0.3 seconds-both ventricles contract, blood is forced to the lungs via the pulmonary trunk, and the rest of the body via the aorta. Atrial diastole: lasting about 0.7 seconds-relaxation of the atria, during which the atria fill with blood from the large veins (the vena cavae).
Detailed explanation-2: -During ventricular contraction, the atria relax (atrial diastole) and receive venous return from both the body and the lungs. Then, in ventricular diastole, the lower chambers relax, allowing initial passive filling of the thick-walled ventricles and emptying of the atria.
Detailed explanation-3: -During systole, the two ventricles develop pressure and eject blood into the pulmonary artery and aorta. At this time the AV valves are closed and the semilunar valves are open. The semilunar valves are closed and the AV valves are open during diastole.
Detailed explanation-4: -Cardiac cycle events can be divided into diastole and systole. Diastole represents ventricular filling, and systole represents ventricular contraction/ejection.