Question

why is blood consired as the most efficient tissue to carry oxygen to different parts of the body

Answer 1

Blood is circulated around the body through blood vessels by the pumping action of the heart. In animals with lungs, arterial blood carries oxygen from inhaled air to the tissues of the body, and venous blood carries carbon dioxide, a waste product of metabolism produced by cells, from the tissues to the lungs to be exhaled.

Answer 2

In the lungs, oxygen diffuses from alveolar air into the blood since the venous blood has a lower partial pressure. The oxygen dissolves in the blood and only a little amount is carried as a physical solution. The remainder of the oxygen is carried in chemical mixture with the haemoglobin in red blood cells. The haemoglobin molecule is the main transporter of oxygen in mammals and several other species. Haemoglobin has an oxygen binding capability of between 1.36 and 1.37 ml O2 per gram Haemoglobin, which increases the entirety blood oxygen capacity seventyfold.