The work which the right ventricle accomplishes is very much less than that of the left, and the right ventricle has a correspondingly thinner wall.

The size of the heart is influenced by the size and the occupation of the individual being larger in the large individual than in the small, and larger in the active and vigorous than in the inactive.

Generally speaking, the heart is about as large as the closed fist of its possessor.
Imperfections of the heart which interfere with its action may be the result of failure of development or disease.

An imperfect heart which can, however, fully meet the limited demands made upon it in intra-uterine life, may be incapable of the work placed upon it in extra-uterine life.

Children with imperfectly formed hearts may be otherwise perfect at birth, but they have a bluish color due to the imperfect supply of the blood with oxygen, and are known as blue babies.