Antibodies and immune system /vaccination /immunisation

ANTIBODIES :-

- these are Immunoglobulin molecules(Ig). 

(a) Each antibody molecule has four 

peptide chains,i.e.two small chains 

called light chains and two longer 

chains are connected by disulphide 

bonds. Hence, an antibody appears like a Y-shaped structure. 

(b) Human body produce different 

types of antibodies. They include IgA, 

IgM, IgE, IgG, etc. IgG can cross the mother's placenta. 

* colostrum contains IgA antibody. IgA 

protects the infant in its initial days from microbes and infection.

Antibody structure

VACCINATION AND IMMUNISATION :-

(1) Vaccination is the process of introduction of weakened or 

inactivated pathogens or proteins (vaccine) into a person to 

provide protection against a disease. 

(2) immunisation is a process by which the body produces 

antibodies against the vaccine (primary response) and 

develops the ability to neutralise pathogens during actual 

infection (secondary response), i.e. The body becomes immune to that antigen or infection. 

(3) vaccine generates memory B and T-cells that recognise 

the pathogens on subsequent exposure and produce an intense immune response. 

(4) in case of requirement of quick immune response like 

tetanus infection, performed antibodies are injected into the 

patient. Even in the cases of snake bite, performed antibodies 

or antitoxin is injected. This is called PASSIVE IMMUNISATION. 

(5) RECOMBINANT DNA TECHNOLOGY has produced 

antigenic polypeptides of pathogen in bacteria or yeast. This 

allowed large scale production of vaccine, e.g.hepatitis-B vaccine produced from yeast cells, etc. 

These topics are very important for NEET students

ALLERGY :-

- it is a hypersensitive reaction of the immune system to 

certain antigens present in the environment. Those agents 

which cause allergy are known as allergens. 

(1) Allergens produce immune response in an individual, e.g.pollen grains, animal dander, dust, feathers, etc. 

(2) IgE antibodies are produced in response to allergens. IgE binds to allergen and then both bind on mast cells. 

(3) This binding cause the release of chemicals like histamine 

and serotonin from the mast cells. These chemicals cause inflammatory reaction in the body. 

(4) Antihistamine, adrenaline and steroids are taken to refuce the symptoms of allergy. 

(5) symptoms of allergy are sneezing, watery eyes, running nose, difficulty in breathing etc. 

(6) Modern day lifestyle has resulted into more sensitivity to environment is common these days. 

AUTOIMMUNITY :-

- it is an abnormal immune response in which immune 

system of the body starts rejection its own body cell or self-

cells and molecules.The diseases caused due to the 

autoimmunity are called AUTOIMMUNE DISEASES, e.g. 

Rheumatoid arthritis, Type-1 diabetes, etc. Autoimmunity is caused due to genetic or unknown reason. 

HUMAN IMMUNE SYSTEM :-

-Human immune system includes:

(1) lymphoid organs, (2) immune cells, (3) soluble molecules like antibodies and (4) lymphoid tissues. 

LYMPHOID ORGANS:-

- These are the organs where Origin, maturation 

and proliferation of lymphocytes occur. They are of following two types. 

PRIMARY LYMPHOID ORGANS:-

- These are the sites where lymphocytes 

differentiate and mature to become antigen-sensitive, e.g. Bone marrow and thymus. 

In bone marrow, all blood cells including 

lymphocytes are produced and B-lymphpcytes mature. 

THYMUS :-

- it is a lobed organ, located near the heart and beneath the breast bone. 

It reduces in size as the age of an individual 

increases. T-lymphocytes develop and mature in thymus. 

SECONDARY LYMPHOID ORGANS:-

- these provide the sites where lymphocytes 

interact with the antigen and proliferate to 

become effector cells, e.g. Spleen, lymph nodes, 

tonsils, peyers patches of small intestine and appendix. 

SPLEEN:-

- it is a large, bean shaped organ which contains 

lymphocytes and phagocytes. It acts as a filter to 

trap blood-borne microbes and contains a large pool of erythrocytes. So, it is known as blood bank of body. 

LYMPH NODES:-

- are small solid structures along the lymphatic 

system. Their function is to trap microorganisms or other antigens that enter the lymph and tissue fluid. 

MUCOSAL ASSOCIATED LYMPHOID TISSUE :-

- (MALT) is formed of masses ofymphoid tissues, 

located within the lining of mucosa of respiratory, 

digestive and urogenital tracts. About 50%of 

lymphoid tissues in human body is formed by MALT. 

https://mbbsprep.blogspot.com/

These topics are very important for NEET students