Immune System - Innate Immunity

The Immune System

The immune system is the human body’s greatest assets.  There are several ways for the microorganisms to enter our body and create a havoc. People are constantly exposed to the diseases causing pathogens, be it all the dirt or dust on the road or say even fall down while playing and etc. All these elements help the pathogens to get into our body. If our immune system stops or fails in functioning and in absence of immunity, humans would fall sick all the time. 

The immune system is the body’s defense mechanism protecting against intruding microorganisms as this mechanism keeps us healthy and active. The overall ability of the immune system is to tackle pathogen and to maintain a healthy life which is referred to as immunity.

Immunity is of two types: Innate Immunity and Acquired Immunity

Innate Immunity

Cells of Innate Immunity

Cells of Innate Immunity

Innate immunity refers to the body’s defense system that has been functioning since our birth. This immunity helps us by providing the natural resistance components including salivary enzymes, natural killer cells, intact skin and neutrophils, etc.  which produce an initial response against the infections at birth prior to exposure to a pathogen or antigens.  It is a long-term immunity in which our body produces the antibodies by its own.

Our body has few natural barriers to prevent the entry of pathogens. The four types of barriers are:

  • Physical barrier

The skin on our body does more than providing us with fair or dark complexions. Our skin acts as a physical barrier to the entry of pathogens. The mucus coating in both our nose and ear are the protective barriers which try to catch the pathogen before it gets inside.

  • Physiological barriers

We know that our stomach uses hydrochloric acid to break down the food molecules, so strong is the acidic environment that most of the germs that enter our body along with the food are killed before the further process is carried on. Saliva in our mouth, tears in our eyes too have antibiotic properties that do not allow the growth of organisms there even though they are exposed to the outer world all day.

  • Cellular barriers

In spite of the physical and physiological barriers, certain pathogens manage to enter our body. As these pathogens are microscopic we cannot hunt it individually, so our body consists of the certain microscopic police force whose function is to patrol the body and keep an eye out for anything suspicious. The cells involved in this barrier are leukocytes (WBC), neutrophils, lymphocytes, basophil, eosinophil, and monocytes. All these cells are all present in the blood and tissues.

  • Cytokine barriers

The cells in our body are smarter than we give them credit for.                                                     For instance, in case a cell in our body experiences a virus invasion, it automatically secretes proteins called interferon which forms a coating around the infected cell and prevents the cells around it from further infections.

Stay tuned with BYJU’S to learn more about immunity and types of immunity.


Practise This Question

Column I lists the components of body defence and column II lists the corresponding descriptions. Match the two columns. Choose the correct option from those given.
 
Column I        Column II
A. Active natural immunity
B. First line of defence
C. Passive natural immunity
D. Second line of defence
  1. Injection of gamma globulins
2. Inflammation and phagocytosis
3. Direct contact with the pathogens that have entered inside
4. Surface barriers
5. Antibodies transferred through the placenta