What are we made up of? This question makes us wonder that what human body is actually made up of. We are always curious about the components which constitute our body. Let’s analyze the atomic, cellular, chemical and microbial constitution of human body.

Atomic body

Human body comprises of staggering 7 octillion or 7 billion billion billion atoms. All these atoms which make up human body were forged in the stars. These atoms came from the stars which exploded billions of years ago. We are actually made of stardust.

The top five elements making this astronomical atomic count are hydrogen, which has about 63% share, oxygen has about 25.6% share, carbon has about 9.5% share, nitrogen has about 1.3% share, and other elements including calcium, phosphorous, potassium, sulfur, chlorine, sodium, magnesium, copper, zinc, iron and some others makes the remaining 0.6 % of atoms in human body. Interestingly, universe also comprises mostly of top four elements found in human body as these are most abundant elements in the universe, excluding helium which comes at second place by atomic count but is chemically inert.

Cellular body

Until recently there had been varying estimates about the number of cells in human body. The count varies due to measuring metric used. If counted using volume metric, it gives an estimate of about 15 trillion cells. Whereas, if counted using weight metric it provides an estimate of about 70 trillion cells. However if density metric is used the number is astounding 724 trillion cells.  But recently scientists have broken down the count by organs and cell types. This has led them to come up with detail volume and densities of cells according to different body parts such as heart muscle cells or fat cells. This has made them come up with a new number. An average human body of weight 70kg consists of about 30 to 40 trillion cells most of which are red blood cells.

There are about 200 different types of specialized cells with 20 different structures in human body like bone cells, cartilage cells, epithelial cells, muscle cells, secretory cells, nerve cells, adipose cells and blood cells. These cells perform different specialized functions like, conduct electric impulses, connect cells and tissues, store materials like fat, produce enzymes and hormones, and support other cells.

Chemical body

The human body mostly consists of oxygen, carbon, hydrogen, nitrogen, calcium, phosphorous, potassium, sulfur, chlorine, sodium, magnesium, iron, copper, zinc and some others. If broken down according to mass of each chemical element present in human body, oxygen is most abundant with about 65% share, carbon with 18% share, hydrogen with 10% share, nitrogen with 3% share and the remaining elements making the remaining 4%.

In terms of chemical compounds, human body consists of water, proteins, fats, minerals and carbohydrates. Water is the highest constituent with 62% of body mass. Proteins are about 16% of body mass. Fats are about 16%, whereas, minerals are about 5% and carbohydrates only account for 1% of body mass.

Microbial body

Until recently it was estimated that bacteria outnumber human cells 10-to-1. Apart from 30 to 40 trillion cells, human body also contains about 40 to 50 trillion bacterium cells of 10,000 different species with 8 million genes, which are about 300 times more than human genes. This suggests that human body is a remarkable giant organism consisting of trillions of human and bacterium cells.

Human Genome

Human genome comprises of about 20000 to 25000 protein coding genes with over three billion DNA base pairs of cytosine (C), guanine (G), adenine (A), and thymine (T). These genes are responsible for different physiological and psychological traits. Adenine is always paired up with thymine and cytosine with guanine. This genetic information coded in the double helix deoxyribonucleic acid (DNA) which is present in each cell, working as an instruction manual which determining the functioning of living cell.

When we come to know about our own body in terms of these astronomical numbers and complex organizations, it boggles our mind and leaves us in an awe.