What makes heart valves open and close?

Answer 1

Valves in the heart close (or open) due to pressure changes in the 4 chambers of the heart. When blood flows into the heart through the pulmonary vein (oxygenated) the heart is in diastole so both the left atrium and ventricle fill. At this point, the bicuspid valve between the chambers is open. When the left atrium becomes full of blood, stretch receptors trigger a response from the SA node - this leads to a contraction of the left atrium (bicuspid valve forced open by pressure). The pressure then exerted from the left ventricle on the left atrium causes the valve to close. This prevents back-flow into the left atrium. When the left ventricle is full, the AV node sends an impulse down the Bundle of His, and to the Prukinje fibres. The left ventricle is subsequently "squeezed" causing blood to flow up the aorta and out to the body. When the heart is contracting like this it is in Systole. Similarly, valves in the aorta close due to the pressure of the blood (caused by gravity). This, again, prevents back-flow in the heart. A similar chain of events occurs in the right side of the heart.

Answer 2

In simple terms it is the result of the pressure your heart produces as it pumps the blood throughout the body and the back pressure when the heart is at rest. When the heart beats (contraction) it produces pressure this pressure forces the valves open when the heart is resting (time between beat) back pressure closes the valves. Without these valves the heart would be unable to send blood to the lungs to get oxygenated (pulmonary valve) or to send blood through the aorta artery (aortic valve) then to the body. There are also 2 other valves (Mitral and Tricuspid) these help control blood flow through the different chambers of the heart (there are 4 chamber is of the heart). Hope this helps.

Steve

Answer 3

Closed blocks the path.

Open allows the item to flow through.