What makes a human body ?

By | July 10, 2021
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Every living thing on this planet is made of almost similar components. The smallest functional structure found in all living organisms ranging from basal micro organisms like bacteria to highly evolved human body, happens to be a “Cell”. In multicellular organisms there are different kinds of cells, each performing a special function. They have the ability to divide in order to replace old dying cells with new cells and sometimes repair themselves.

How a human body is made?

Human body is made up of trillions of cells. They often work in groups to perform a specific function and cells performing different functions also cross-talk to each other. The complexity of a cell type, the way these cells are organized and interact with each other gives us the humans our unique identity.

Atoms- Molecules :

The smallest component of our body is an “Atom“. These atoms act as the building blocks to form Elements” ( Such as carbon atoms combine to form carbon element ) -( Atoms and elements : difference). Unlike elements (substance entirely made from one type of atom), molecules can be made from the same or different elements.

Two or more different (heteronuclear ) or similar (homonuclear) atoms will combine to form “Molecules” with the help of molecular bonds – for example, 2 oxygen atoms combine to form O2 gas molecule, two Hydrogen atoms and one Oxygen atom combine to form a water molecule (micro molecules). Glucose is a combination of 6 Carbons,12 hydrogens and 6 Oxygen atoms (carbohydrate), DNA is  acronym for deoxyribonucleic acid (Nucleic acids), Pepsin (protein), Cholesterol (lipid) are examples of four major biological macromolecules crucial for our body . The function of the molecule depends on its unique three dimension structure.

Atoms of most elements are not able to exist independently. Atoms for molecules and ions.

These molecules or ions aggregate in large numbers to form the matter that we can see, feel and touch.

Atoms and molecules

Most of our body consists of three elements – Oxygen (65%), Carbon (18.5%) and Hydrogen (10%). The other elements present in significant amounts are Nitrogen, Calcium and Phosphorus. A human body is mostly made up of 25 chemical elements. All these elements with the exception of hydrogen were created in the interiors of stars where the environment was super-hot with high-pressure environment, which was possible when stars violently came to the end of their lives. Hydrogen gas was created when the “Big Bang” happened that also created our Universe.

These simple elements join to form complex macromolecules, vital for proper functioning of cell. The contribution of carbon, Oxygen and Hydrogen is immense which is evident from the fact that these elements in combination account for many important macromolecules required for proper functioning our body.

Four major carbon compounds / Macromolecules which are present in our body are:

Nucleic acids: The DNA and RNA molecules harbor the instructions necessary for making all the proteins made by our body required for its proper function.

Proteins: Proteins are important molecules as many organs such as brain, as well as muscles, hormones and antibodies are made of proteins.

Lipids: Lipids form the outer layer of cells and are made up of carbon and hydrogen atoms.

Carbohydrates: These macromolecules are our major source of energy. Carbohydrates are made up of Carbon, Oxygen and Hydrogen.

Cells. Tissues and organs

Cells – Tissues and Organs:

Millions of different molecules are required to make a “cell“. It is estimated that 37 trillions cells are present in average human. These cells belong to different types or groups performing a particular function.

The cells which share similar function are grouped together to form “Tissues” such as Stomach, Liver, Heart tissue , Blood ( a tissue in liquid form) etc.

Different kinds of tissues combine to form larger “Organs” and each organ works like a machine performing its own function, An example of Organ is Heart, which plays a important role in blood circulation . All major organs act in concert to ensure proper functioning of the entire body system.

Atoms- Body system

Image credit :

Tissues and organs – Smart Servier

Atoms, Molecules – Pixabay