PHYSIOLOGY
GENERAL PHYSIOLOGY
|
Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
|
|
|
the cordae tendinae pull them closed.
|
|
|
blood rushing back to the ventricles is caught in the little ‘cups’ of the valves and pushes the edges together.
|
|
|
the elastic artery pulls them closed.
|
|
|
the ventricles put more pressure on them than the artery.
|
Detailed explanation-1: -As the ventricles contract, ventricular pressure exceeds arterial pressure, the semilunar valves open and blood is pumped into the major arteries. However, when the ventricles relax, arterial pressure exceeds ventricular pressure and the semilunar valves snap shut.
Detailed explanation-2: -The semilunar valves act to prevent backflow of blood from the arteries to the ventricles during ventricular diastole and help maintain pressure on the major arteries. The aortic semilunar valve separates the left ventricle from the opening of the aorta.
Detailed explanation-3: -The semilunar valves are closed because the ventricular pressure is lower than that in the aorta and the pulmonary artery (fig. 1.1). The contraction is represented by a colour change of myocardium. The ventricles contract and all valves are closed, so no blood can be ejected.
Detailed explanation-4: -aortic valve: located between the left ventricle and the aorta.