Soldiers Of Defense

Defense mechanism can be classified into:

i. Non-specific

ii. Specific

The action of B lymphocytes is the type of specific defense as the specific defense is the system which identifies and destroy pathogens which enter the body. Lymphocytes are capable of destroying pathogens. B-lymphocytes produce an army of protein in blood, known as antibodies in response to pathogens.

Whereas, production of sebum, the action of hydrochloric acid in the stomach and action of lysozyme in saliva is a nonspecific first level defense mechanism.

The lymphocytes mainly found in lymph and are responsible for producing the immune response.

Lymphocytes are of two types—

i. B-lymphocytes

ii. T-lymphocytes

B-lymphocytes

B-lymphocytes is also known as B-cells and they mature in the bone marrow.

They produce an army of protein in blood, known as antibodies in response to pathogens. They are involved in the antibody-mediated immunity(AMI) or humoral immunity.

T-lymphocytes

T-lymphocytes is also known as T-cells and they mature in the thymus gland.

They help B-cells(B-lymphocytes) to produce antibodies and are capable of destroying the cancer cell. They are involved in the cell-mediated immunity(CMI).

Antigen is the molecule capable of inducing the immune response to the host organism. Antigens are targeted by the army of proteins called antibodies. Each antibody is produced by the immune system that bond in a specific fashion with antigens. Several antigens are possessed by a membrane of red blood cells. Main two blood grouping which is widely used are ABO and Rh.

ABO blood grouping

ABO blood grouping system is one of the most common type of blood grouping. ABO blood groups are controlled by gene I.

ABO blood grouping mainly based on the presence or absence of antigen A and antigen B on the surface of red blood cells.

Rh grouping

Another antigen Rh factor is present in the membrane of the red blood cells. People who have these antigens are called Rh +ve and the people who do not have these antigens are calked Rh-ve.

Everybody cannot receive blood from all blood groups because when foreign antigen reaches to the blood, it starts its defense activity. The antigen present in the received blood and antibody in the recipient's blood will react with each other and form a blood clot.

For example, if donor blood group is A and recipient blood group is B, then the recipient's antibodies attach to donor red blood cells and cause clumping which may cause hemolysis.

Similarly, if Rh—ve person exposed to Rh+ve blood then it will form antibodies against the Rh antigens.

To destroy mosquitoes at home and in the school premises we should follow following steps—

i. We should close the unused wells or tanks.

ii. We should even put small amount of kerosene in the unused water to prevent egg laying.

iii. We should use Insecticides to prevent their growth.

iv. We should use mosquito nets.

v. We should maintain public hygiene by proper disposal of wastes.

vi. We should keep the water reservoirs clean.

vii. We should maintain the personal hygiene.

viii. We can also Use insect repellents.

ix. We can even destroy mosquitoes by spraying BHC, DDT

Antibiotics are the chemical substance which can kill or retard the growth of other diseases causing microbes.

The first antibiotic was penicillin which was discovered by Alexander Fleming.

Alexander Fleming was working on staphylococcus bacteria. He observed the growth of mold around which the bacteria did not grow. He found that it was chemical penicillin which was produced by Penicillium notatum.

Ernst Chain and Howard Florey discovered the function of penicillin as an antibiotic. Alexander Fleming, Ernst Chain, and Howard Florey were awarded by the Nobel prize in 1945.

Regular use of antibiotics may cause side effects such as—

i. They may kill the useful bacteria.

ii. Develop immunity in the pathogens against antibiotic.

But still, antibiotic play an important role in improving our capacity by treating diseases such as plague, diphtheria, leprosy etc. They have greatly contributed towards the welfare of the human society. So we can say antibiotics are useful.