Give biological reasons for the following statements:
The left ventricle of the heart has a thicker wall than the right ventricle.
Topic: Thickness of the left ventricle wall
Answer
Because the LEFT ventricle pumps blood through the SYSTEMIC circulation — to the whole body, including the feet and the brain, and against gravity. That requires a much HIGHER PRESSURE, and therefore a thicker, more muscular wall.
The RIGHT ventricle pumps blood only as far as the LUNGS, a short distance at low pressure, so a thinner wall suffices.
The answer must compare the DISTANCE and the PRESSURE required — that is the whole reason.
THERE IS A SECOND REASON worth adding: the lungs are delicate, and blood driven into them at systemic pressure would damage the thin alveolar capillaries. So the pulmonary circuit MUST be kept at low pressure — the thin right ventricle is not merely sufficient but necessary.
This is one of the advantages of DOUBLE CIRCULATION: keeping the two circuits separate allows them to run at completely different pressures, which a single circuit could not do.