Question

Left ventricle of heart has thicker wall, and it pumps blood in aorta under high pressure but it is not so in case of right ventricle. Why is it so?

Answer 1

Nature has designed this on purpose. Please go through this first.

Explanation:

Reason 1

Please consider location of lungs: these are adjacent to heart located in chest cavity. Pulmonary artery takes blood from right ventricle to lungs: thus traverses a very short distance. Blood pressure in pulmonary circulation is sufficient to move blood through this circuit before blood returns to left atrium.

(https://socratic.org/questions/the-ventricles-pump-deoxygenated-blood-to-lungs-at-about-how-many-mmhg-and-into-)

Compared to this, aorta takes away blood to distant organs such as tips of extremities, etc. from where blood must again return to heart. Left ventricle pumps blood under high pressure to achieve this: wall of left ventricle is thick and muscular to push blood in systemic circulation through aorta.

Reason 2

Blood volumes entering pulmonary circulation and systemic circulation are exactly same: that is amount of blood ejected from each of the right and left ventricle per heart beat are equal. This is despite the dissimilarity between structure of two ventricles and difference of length of two circulatory circuits.

Blood from both circuits must come back to atria when these chambers are in diastole and exactly same amount must return to left and right atria. Thus blood may flow comparatively slowly through pulmonary circuit, hence increase in blood pressure not desired.

Same amount of blood is travelling through both circuits, but it is travelling different distances in same time. Blood in pulmonary capillaries travels slowly, under low pressure, which allows respiratory gases to diffuse well. Carbon dioxide is unloaded so that blood flowing around alveoli of lungs can pick up oxygen.