Heart Valves
The following is a simplified explanation of how the heart valves function.
Blood being pumped around the body always flows in the same direction. The direction of this flow is controlled by valves within the heart with each of the four chambers having a seperate valve.
Each heart beat begins with a contraction (Systole phase) which starts at the top of the heart with the two atria. As the chambers contract the valves between the atria and the ventricles (Mitral & Tricuspid valves) open, and blood is forced out of the atria into the ventricles.
Simultaneously the valves between the heart and the artries (Aortic & Pulminary valves) close tightly to stop blood flowing back from the artries and into the heart.
As the contraction continues, the ventricles start to contract and the Mitral & Tricuspid valves between the atria and ventricles now close so blood can no longer flow between the two chambers.
At the same time the Aortic & Pulminary valves open fully and the contraction of the ventricles forces blood out of the heart and into the artries and around the body.
The heart then briefly relaxes (Distole phase) and the two atria re-fill with blood returning from the viens and the cycle begins again. So at any given instant the heart will only have two of it's four valves open.
So the heart has four valves in all:
- Tricuspid valve: located between the right atrium and the right ventricle
- Pulmonary valve: located between the right ventricle and the pulmonary artery
- Mitral valve: located between the left atrium and the left ventricle
- Aortic valve: located between the left ventricle and the aorta
One of the more common problems with the heart is that one or more of the valves will not open or close completely and "Leaks". If the leaking is significant a valve may need to be replaced. When a doctor listens to your heart he may be able to hear a valve leaking.
In addition to the valves inside the heart, the veins also have small valves throughout the body.
These smaller valves (Venous valves) help ensure that the blood flows in the right direction towards the heart. The contraction and relaxation of muscles around the body during exercise, squeezes the viens and helps to push the blood along, back towards the heart. (Just one of the reasons that gentle exercise is good for you).