Q.What is Methaemoglobin?

Blood is a specialised fluid connective tissue that transports substances between every part of the body, made of two components: plasma, a liquid matrix that makes up about 55% of total blood volume, and the formed elements - red blood cells (erythrocytes), white blood cells (leucocytes) and platelets - which make up the remaining 45%. An average 70 kg adult carries roughly 5 litres of blood, and the fraction of that volume occupied by cells is called the haematocrit (packed cell volume). Red blood cells, at 4.5-5.5 million per cubic millimetre, vastly outnumber the other formed elements; they are biconcave, nucleus-free discs packed with the oxygen-carrying pigment haemoglobin and have a fixed 120-day lifespan before being broken down in the spleen. White blood cells, far less numerous at 6000-8000 per cubic millimetre, are nucleated, amoeboid defence cells split into granulocytes (neutrophils, eosinophils, basophils) and agranulocytes (lymphocytes, monocytes), with neutrophils th …