Explain the History and Milestones of the Concept of Blood
In this section, we will discuss about the historical development of the concept of blood and blood cells. This discussion is an overview of sequence of events that took place during different times in the past. Let us go through it.
a) The ancients must have observed that if an animal or a man lost a considerable quantity of blood, it generally did not survive. This must have led them to associate blood with life. Ebers Papyrzrs said that in ancient Egypt, it was believed that food in the stomach was turned into blood by heart.
b) According to the ancient European doctrine of four humors, blood was one of the humors which makes the body. The other three humors were phlegm, black bile and blue bile. The blood is considered as one of the four humors.
c) The Ayurvedic concept of three humors is very similar. The three humors are kapha (phlegm), pitta (bile) and vayu (air). Health is thought to be a state of balance of these humors. In this system, air comes closest to blood.
d) In the recent history of growth of our knowledge about blood, the advent of microscopy in the seventeenth century was an important milestone. Antony Van Leeuwenhoek is considered a pioneer in microscopy. He examined blood under the microscope and could describe red blood cells and even measured their size.
e) In the eighteenth century, extensive studies on blood and related structures such as lymphatics and thymus were undertaken by William Hewson. He described the leukocytes and demonstrated that coagulation was due to the changes in the plasma rather than the blood cells, and hence Hewson is called the 'father of hematology'.
f) In the nineteenth century, Paul Ehrlich used dyes for staining cells, which helped him to distinguish different types of blood cells and red cell changes in diseases and also identified the different types of white blood cells.
g) In the twentieth century, George Whipple's studies on the relationship between diet and haemoglobin, George Minot's discovery of the liver treatment for pernicious anaemia and William castle's discovery of intrinsic and extrinsic factors were some of the milestones in hematology.