What happens when SARS-CoV2 (COVID-19 virus) enters your body?

SARS-CoV2 causes COVID-19. It is a contagious viral infection that attacks primarily one's throat and lungs. It belongs to the family of Coronaviruses. It is named for the crown-like spikes on it's surface.

Electron Microscope image of Coronavirus

What happens in the body when you contract coronavirus?

It is the primary task of every living creature to look for ways to maintain it's existence. This can be done by reproducing.

In order to reproduce, the coronavirus must infect living cells.

Inside a virus, genetic material contains information to make more copies of itself.

Parts of a Virus

   A protein shell provides a hard protective enclosure for the genetic material as the virus travels between the people it infects. An outer envelope allows the virus to infect cells by merging with the cell's outer membrane. Projection from the outer membrane are spikes made of protein molecules. Both influenza and n-coronavirus use their spike like a key to get inside a cell in your body where it takes over the cell's internal machinery repurposing it to build the components of new viruses.

When an infected person talks, coughs or sneezes, droplets carrying the virus lands in your mouth or nose and then move into your lungs.

Now the virus is inside you. Once inside your body, the virus comes in contact with cells in your throat, nose or lungs. One spike on the virus inserts itself onto a receptor molecule on your healthy cell membrane like a key and a lock.

Image of virus linking with receptor molecule (of human body)

This allows the virus to get inside your cell. A typical flu virus would travel (inside a sac made from your cell membrane) to your cell's nucleus that has all it's genetic material.

But the coronavirus doesn't need to enter the host cell nucleus. It can directly access parts of the host cell called Ribosomes.

Human Ribosome

Ribosomes use genetic information in the virus and make viral proteins such as the spike on the virus' surface. A packaging structure in your cell then carries the spikes in vesicles which merge with the cell's outer layer i.e. the cell membrane. Then a virus begins to bud off from the cell's membrane.

How can you develop pneumonia symptoms

At this stage, the virus is multiplying rapidly in the body.

Let's look into the lungs.

Lungs and Alveoli

Each lung has a separte section called lobes. Normally as one breathes air flows freely through the trachea, the wind pipe, through large tubes called Bronchi, through smaller tubes called Bronchioles and finally into tiny sacks called Alveoli. Airways in Alveoli are flexible and springy. When you breath in, each sack inflates like a small balloon and when you exhale, the sacks deflate. Small blood vessels called capillaries surround your alveoli.

Oxygen from the air you breathe passes into your capillaries and then carbon dioxide from your body passes out of your capillaries into your alveoli so that your lungs can get rid of it when you exhale. Your airways catch more germs in the mucus that lie in your trachea, bronchi and bronchioles.

In a healthy body, hair-like cilia lining the tubes would push mucus and germs out of your airways where you expel them by coughing.

 Normally cells of your immune system attacks germs and viruses and enter your alveoli. However, if your immune system is weak like in the case if corona virus infection, the virus can overwhelm your immune cells and your bronchioles and alveoli become inflamed as your immune system attacks the multiplying viruses.

The inflammation can cause your alveoli to fill with fluid making it difficult for your body to get the oxygen it requires. You could develop lobar pneumonia where one lobe of lungs is affected or you could have bronchopneumonia where it affects many areas of both lungs. Pneumonia can cause difficulty to breathe, chest pain, coughing, fever and chills, confusion, headache, muscle pain and fatigue. It can also lead to more serious complications. Respiratory problems occur when your breathing becomes so difficult that you need a machine called ventilator to help you breathe. These machines save lives.

Whether you would develop these symptoms would depend on factors like your age and if you have an existing condition.