Question

1. Immune system is an important system in the body. Discuss the followings:

1) The role of antibodies and antigens in blood typing?

2) The types of immunity in relation to disease protection?   .

2. Is there any other factor besides the nephron which control the reabsorption of water and certain molecules for osmoregulation? Substantiate your answer with reasons? .

3. Analyze the specific role of liver in each of the following: 1. Carbohydrate, lipid and protein metabolism, 2. Processing of drugs and hormones, 3. Excretion of bilirubin, 4. Synthesis of bile salts and 5 Activation of vitamin D? .

Answer 1

1. 1) The role of antibodies and antigens in blood typing

In ABO blood group system, there are two types of antigens on the RBC surface - A and B antigens. And there are antibodies in the serum. A patient with a particular antigen in RBC will lack the corresponding antibody in the serum.

For example, a person with blood group A has 'A' antogen on RBC surface. He doesnt have anti-A antibodies, but possess anti-B antibodies in the serum.

The different ABO bloodgroup types and the corresponding antigen and antibody are:-

In Rhesus blood grouping, an individual with the Rh antigen (D) is Rh positive and individual without Rh antigen is Rh negative. The anti-D antibodies that react against D antigens are not usually present in the blood.

Blood typing is the classification of blood, based on the presence or absence of antibodies and antigen on the surface of red blood cells. Here, the  blood sample is mixed with antibodies against type A and B blood and observed for agglutination.  If blood cells agglutinate, it means the blood reacted with that particular antibody indicating the presence of that antigen.

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1. 2) The types of immunity in relation to disease protection

Immunity can be broadly divided into Innate immunity and adaptive immunity.

INNATE IMMUNITY is the body's first level of defence against a microorganism. It is a rapid response and is non-specific. Innate immunity includes physical barriers like lysozyme in tears,the complement system, phagocytic cells - macrophages and neutroplils, natural killer cells etc.

ADAPTIVE IMMUNITY is the second line of defence against a microorganism. It is more delayed than the immune response , but is specific against a particular pathogen.It can be divided into Humoral immunity or cell mediated immunity.

In humoral immunity, the pathogen is presented to the CD4 + T lymphocytes by the antigen presenting cells with the help of MHC molecules. This causes activation of the CD4+ helper T cells. This activated helper T cells stimulates B lymphocytes which are transformed into plasma cells leading to antibody production.

In cell-mediated immunity, the pathogen is presented to the CD8 + T lymphocytes by the antigen presenting cells with the help of MHC molecules. This causes activation of the CD8+ cytotoxic T cells. This activated cytotoxic T cells mediates destruction of the pathogen infected cell.