• The?ventricles?have thicker muscle walls than the atria as they are pumping blood out of the heart and so need to generate?a higher pressure
• The left ventricle has a thicker muscle wall than the right ventricle?as it has to pump blood at high pressure around the?entire body, whereas the right ventricle is pumping blood at lower pressure to the?lungs
• The?septum?separates the two sides of the heart and so?prevents mixing of oxygenated and deoxygenated blood

Structure of the heart showing the different valves

The function of valves

• The basic function of all valves is to?prevent blood from flowing backwards
• There are two sets of valves in the heart:
  • The?atrioventricular valves?separate the atria from the ventricles
  • The valve in the right side of the heart is called the?TRICUSPID?and the valve in the left side is called the?BICUSPID
  • These valves are pushed?open when the atria contract?but when the?ventricles contract they are pushed shut?to prevent blood flowing back into the atria
  • The?semilunar valves?are found in the two blood arteries that come out of the top of the heart
  • They are unusual in that they are the?only two arteries in the body that contain valves
  • These valves?open when the ventricles contract?so blood squeezes past them out of the heart, but then shut to avoid blood flowing back into the heart

轉(zhuǎn)載自savemyexams