Which heart valve closes first in the heart?

Mitral valve. Mitral closes first followed by tricuspid (s1) then aortic followed by pulmonic (s2).
Triscupid valve. As the heart contracts, the tricuspid valve is able to close before the mitral valve because it faces a lower systemic venous pressure compared to a slightly higher pulmonary venous pressure faced by the mitral valve.

Related Questions

Is the heart valve a tissue?

Yes. The heart valve is specific tissue made of collagen that is thin layered yet durable. Read more...
Yes. The valves are tough fibrous tissue that are very durable. Over your lifetime the valves open and close millions of times. Read more...

Is a sticky heart valve inherited?

Definition. Heart valves function to seal a chamber (closed) so blood can fill. When the chamber contracts the valve opens to allow blood to exit. When the valves do not function properly, we usually refer to a valve leaking or not closing correctly (insufficieny or regurgitation) or not opening correctly (stenotic). So when you describe the vavle being "sticky" can you describe it in these terms? Read more...

What is the function of heart valve?

To direct flow. A heart valve functions to allow unidirectional blood flow. When chambers of the heart contract, one heart valve will open and one will close; this effectively allows only one low resistance pathway for the blood to follow. If there were no valves, blood would flow backwards from where it just came as well as forwards. This would significantly decrease the effectiveness of the heart as a pump. Read more...
Regulate. Flow of blood in a single direction across different chambers. Read more...