Which ventricle has a thicker wall and why?

• A. Right ventricle because it has higher pressure
• B. Left ventricle because it must pump to systemic circulation
• C. Left ventricle because it pumps to lungs
• D. Right ventricle to ventricles only

Answer: (B)

The thickness of a ventricle’s wall reflects the pressure it must generate. The left ventricle must pump blood into the systemic circulation, which requires high pressure to overcome systemic resistance; therefore its muscle layer is thick. The right ventricle only needs to push blood to the lungs through the low-resistance pulmonary circuit, so its wall is thinner. This is why the left ventricle, with its need to pump to systemic circulation, has the thicker wall. The other choices mix up which ventricle generates higher pressure or which circuit each ventricle serves.