RESPIRATORY SYSTEM AND COVID-19..

         LITTLE BIT ABOUT OUR RESPIRATORY SYSTEM     

In human beings many organs take part in the process of respiration , these include : Nose, nasal passage, trachea, bronchi, lungs , diaphragm etc. In this section we will try to understand the mechanism of respiration and how it is effected when a person gets a SEVERE CASE of COVID-19 disease.

• The human respiratory system begins from the nose. Our nose has two holes in it which are called nostrils. There is a passage in the nose behind the nostrils called the nasal passage ( or nasal cavity ). The air for respiration is drawn into our body through nostrils in the nose.
• 
  From the nasal passage , air enters into pharynx and then goes to the windpipe or trachea. Trachea is a tube which is commonly known as windpipe. The windpipe does not collapse even when there is no air because it is surrounded by or supported by the rings of cartilage.
  
• 
  The trachea runs down the neck and divides into two smaller tubes called bronchi ( sing. bronchus) . The two bronchi are connected to the two lungs which lies in the thoracic cavity.
• further bronchi divides into smaller tubes called bronchioles , and the smallest bronchioles have small air sacs at their end called alveoli. The alveoli is all over surrounded by the blood capillaries.
  
• The alveoli can be seen as the most important functioning unit of the lungs. The lining of alveoli is so thin that exchange of gases can easily take place through it. 
  
                                                               alveoli ..

How does COVID-19 affect our lungs ..

One of the most severe cases of COVID is the one in which the patient's lungs has been infected. This leads to shortness in breathing and in some cases the person dies as well.

When the coronavirus enters our body, it mainly attacks the boundary cells of our lungs.

Now the question arises that why only the lung cells why not brain cells or any other cell of our body? 

This is so because the coronavirus has spikes all over its structure , these spikes are called protein spikes and the boundary cells of our lungs also have spikes which are called ACE2 RECEPTOR ( Angiotensin converting enzyme 2 ) . Now, we all know that our cell membrane is a semi-permeable structure i.e. it allows entry and exit of only specific types of substances in and out of the cell. When the protein spikes of the virus get attached to the ACE2 RECEPTOR then they are allowed to enter the cell of our lungs.

 

(It is to be noted that Ace2 Receptor are present in other organs such as gall bladder, kidney  intestines etc. But as in most cases the virus enters the body either through nose or through mouth thus it affects the lungs )

Back to the story, as the virus enters the cell , it kind of hijacks the nucleus of the cell and  through the codes of its RNA, it gives the instruction to the nucleus to make multiple copies of the itself, these new viruses now leave the cell and the cell gradually gets destroyed. 

( the incubation period of COVID is between 2 - 10 days after the person is infected by the virus ) 

When the first outburst of virus takes place in our body , at that time our immune cells gets active. Our INNATE immune system starts fighting against the virus now. This is the reason why we also get fever  when we have COVID because our body creates a hostile environment for the virus by increasing the temperature of the body  in order to kill the virus . Gradually our ADVANCED or ADAPTIVE immune system gets active and it starts producing antibodies , these antibodies get attached to the spike protein of the virus , and the virus finally gets destroyed by the action of MACROPHAGES ( a type of immune cell ) . 

                        

How coronavirus kills ?..

In some severe cases , this fight between our immune cells and the virus near the boundary of lung cells secretes a viscous liquid in our alveoli called PUS ( nothing but a mixture of dead matter, that includes dead immune cells, viruses, bacteria or even fungi).

Due to this , the exchange of gases now becomes harder and even very problematic for the patient, this leads to reduced oxygen levels, shortness of breathing etc. 

And in some cases , the person dies as well. 

          pus inside alveoli ..blocking the pathway for exchange of gases

How will vaccination help ?...

In vaccination , an attenuated form ( weakened form ) of virus is injected in our body and the immune cells of our body very easily kill this virus . Now the memory cells of our immune system ( formed by the dendritic cell ) creates a memory of the specification of this particular virus, so that , when the virus enters our body again in non- attenuated form or in more vigorous form , then our immune cells ( specifically B- lymphocytes)  can create antibodies in a faster rate than usual and will help to fight against the virus. 

Therefore, it is a request to all that please get vaccinated and don't hesitate for taking the vaccine. It is true that  even after getting vaccinated you can get infected by the virus again , but this time your body will have enough strength to tackle this virus without harming the immunity of your body.( If you get a mild fever after getting vaccinated then it means that the immune cells are fighting against the attenuated virus and the vaccine is working properly in your body ). 

                         Thank you..