Question

Which organ plays a major role in the breakdown of haemoglobin?

Answer 1

            When we breathe in oxygen, the red blood cells transport it around to every cell in the body – a critical process that has far-reaching evolutionary consequences.  The advent of aerobic respiration, which added the oxygen-utilising tricarboxylic acid cycle and electron transport system onto anaerobic glycolysis, allowed aerobic organisms to extract 18 times more energy from glucose in the form of ATP.  Initially, organisms relied on diffusion to transport oxygen to their cells, an inefficient system that kept them microscopic in size.  Then with the development of the body cavity came a primitive circulatory system involving the flow of interstitial fluid through the action of muscular movement; yet, body size remained small, as this system of circulation was limited in its effectiveness.  Nematode worms have a primitive type of body cavity (pseudocoelom) and circulation; these tiny animals consist of just under a 1000 cells and as such are barely visible with the naked eye.  With the advent of a true circulatory system to transport highly specialised red blood cells close to every cell in the body no matter how large the organism, so that oxygen could now reach all cells, body size was able to expand radically up to the largest animal to currently inhabit the earth: the blue whale, which can weight up to 150 tons and stretch 100 feet in length from head to tail.