Cells that make up our body

Life, in short, is a complex melange of cells. According to recent estimates, on average, there are 36 trillion cells in men, 28 trillion in women, and 17 trillion in a child. In this medley, scientists recognize 400 types of cells in the human body, each with its distinct shape, size and function, perfected over billions of years through evolution. Recently, scientists created the first human cell tree map to understand how cells are distributed throughout our body. The insights give us a sense of large-scale patterns of their numbers and weight.

There are more red blood cells and platelets in the human body than any other cells—about 29 trillion of them, nearly four times the number of all others. These cells do not have a nucleus and are among the smallest of cells. At 3.4 trillion, white blood cells, which include lymphocytes, T-cells, and neutrophils, come next, followed by epithelial cells that form our skin and the lining of various organs. In addition to all these human cells, our body has a whopping 38 trillion bacterial cells!

Guess how much all these trillions of cells weigh? In an average human weighing 70 kg, cells comprise nearly two-thirds of the body weight! Skeletal myocytes—long, fibrous muscle cells attached to the bones of the bones of our skeleton—comprise about half of this weight, over 20 kg, although they make up only 0.002% of the nucleated cell count. At about 12 kilograms, adipocytes or fat cells come second, followed by red blood cells and epithelial cells. 

Although there’s no best size for a cell, our body has cells across the range—from platelets that are about 2 microns to muscle cells (myocytes) that are up to 3 cm long. The bigger the cell size, the fewer their numbers in the body. Thanks to this exciting medley, life functions as we know it.