A virus hijacks the cell’s internal systems and commands it to produce only biomolecules needed for making more viruses. Finally, the infected cell bursts open, and numerous viral particles are released, which, in turn, infect neighboring cells or be carried out as part of droplets in human breath externally.

The organelles in a cell that are essential to produce multiple new viruses need energy; the main source of biochemical energy is adenosine triphosphate (ATP) — the universal energy currency of cells.

There are more viruses than stars in the universe. Why do only some infect us? Yet, most of the time, we manage to live in these virus field world relatively free of illness. The reason has less to do with the human body’s resilience to disease than the biological quirks of viruses by themselves. We live in a microbial world, which means that we constantly encounter microorganisms that could harm our health. The human immune system continuously defends us against these threats to our survival.

WHAT IS THE IMMUNE SYSTEM?

The immune system is a network of cells, tissues, and organs that work together to defend the body from harmful germs. When bacteria, viruses, and other germs invade our bodies, they multiply and attack. This invasion is called an infection. The infection causes diseases that make us sick.

Our (Innate) immune system protects us from the diseases by fighting the invading germs. Here’s how an immune responses work –

Our immune system sounds the alarm so your body knows there’s an infection.

It begins releasing antibodies to fight the germ — think of antibodies as soldiers designed to fight off the specific germ you have. This process can take a few days.

The antibodies work to attack, weaken, and destroy the germ.

Afterward, your immune system REMEMBERS the germ (Adaptive Immunity). If the germ invades again, your body can recognize it and quickly send out the right antibodies so you don’t get sick!

This protection against a certain disease is called immunity. In many cases, the immunity lasts your whole life.

In the next part we will discuss, what are vaccines and how do they work in a simple way.