Role of valves in allowing the heart to pump blood in a single direction

Question: How do different valves in the heart allow blood to flow in a single direction?

Hey y’all!

The heart is made up of various parts that allow it to function as an efficient pump but one of the most crucial parts are the 4 sets of valves that allow blood to flow in a single direction. These valves are a lot like the valves found in the piping of your homes and only open when pressure is applied in one direction, preventing the backflow of blood.

The two main types of valves are atrioventricular…

• Tricuspid Valves (between right atrium and right ventricle)
• Bicuspid / mitral valves (between left atrium and left ventricle)

and semilunar valves

• Pulmonary semilunar valve (to the lungs)
• Aortic semilunar valve

Each of these valves have a set of flaps or cusps that can be thought of as the “gates” that open to allow blood to enter. These cusps allow the valves to open when pressure increases on one side of the valve and close when the pressure increases on the other side.

Now let us quickly run through how blood pressure in each of the components of the RIGHT* side heart help to allow blood to continually flow in a single direction:

1. As blood flows through the vena cava into the right atrium, the pressure in this chamber increases. During this time the tricuspid valves are closed
2. When the pressure in the aorta surpasses a critical value due to the contraction of the atrium, it becomes high enough to push the tricuspid valves open
3. As blood fills the ventricle, the ventricular pressure increases and when all the blood has entered the ventricle, the pressure here becomes high enough to push back the tricuspid valve closed.
4. Concurrently as the ventricles contract, the ventricular pressure also becomes high enough to push the pulmonary semilunar valves open, allowing the blood to leave the ventricle to the lungs through the pulmonary artery.

the left works in the same way, just with bicuspid valves and aortic semilunar valves instead

You can see how the opening and closing of valves due to changes in pressure of the chambers would allow the blood to flow in a single direction. Why is this incredibly important? This is to ensure that the heart is able to pump as much blood as it can efficiently. If backflow of blood to other parts of the heart occurs, the blood will never reach its intended destination!

I hope I have been able to explain how the various valves in the heart ensure that your blood is being pumped efficiently around the body! ^-^