Biology-HEART

Left side- oxygenated blood from Lungs

Right side-deoxygenated blood from the body 

Atrium:- thin walled

           -elastic and stretches as it collects blood

           - only pumps blood a short distance- to lungs or rest of body

Ventricle:- thicker muscular wall 

              - pumps blood a short distance- to lungs or rest of body 

• Blood has to pass through tiny capillaries in the lungs in order to present a large surface area for exchange of gases. 
• In doing so , there is a very large drop in pressure so therefore blood flow to rest of body is very slow 
• Mammals have a system in which blood is returned to the heart to increase its pressure before it is distributed to the rest of the body. 
• it is important to keep deoxygenated blood in the pump on the right

Because the right ventricle has to pump blood to the lungs, it has a thinner muscular wall than the left ventricle . The left ventricle has thicker muscular wall enabling it to create enough pressure to pump blood to body. No mixing of blood, pump in time with each other, both atria contract together and then the ventricles contract together. 

Between the atrium and the ventricle- the valves prevent backflow of blood into the atria when the ventricles contract. There are 2 sets of valves:

• The left atrioventricular (biscuipid) valve: Left side of heart..
• The right atrioventricular (triscuipid) valves: right side of heart..

Right side

Left side: