1. Components of Acquired Immunity NISARG RAVAL

2. IMMUNE  WHAT IS IMMUNE SYSTEM? Immune system is remarkably versatile defense system. It is able to recognize minute and subtle chemical difference thet difference that distinguish foreign pathogen from other.  WHAT IS IMMUNITY? Immunity is capability of multicellular organism to resist harmful microorganism from entering it. It involves both specific and non-specific components.

3.  VARIOUS TYPES OF IMMUNITY. Immunity can be classified into various types depending upon particular criteria.  On the basis of whether immune system is itself involved directly [Active Immunity] or indirectly [Passive Immunity].  Immunity is governed by cells [Cell Mediated Immunity] or molecules present in body fluids [Humoral Immunity].  Immunity present right from birth [Innate Immunity] or it is develop later on by exposure to invader [ Acquired Immunity].

5.  INNATE IMMUNITY : Innate Immunity is the first line of defense in healthy individuals. It is present right from birth. It is non-specific. No memory cells are formed. Present in lower forms of life. COMPONENTS: -Anatomic barriers. -Physiological barriers. -Phagocytic barriers. -Inflammation.

6.  ACQUIRED IMMUNITY : Acquired Immunity is the second line of defense. Acquired after the exposure to antigen. It is specific for antigen, to infective. Memory cells are formed. Present only in Vertebrates. It develops more slowly, more effective defense against infective.

7.  IT IS SUBDIVIDED INTO 2 MAJOR TYPES : 1.NATURALLY ACQUIRED IMMUNITY : It occurs through contact with infection. 2.ARTIFICIALLY ACQUIRED IMMUNITY : It develops only through actions such as vaccinations. Both Naturally and Artificially Acquired Immunity can be further subdivided into : 1.ACTIVE ACQUIRED IMMUNITY : It is induced in the host itself by the antigen and lasts much longer sometime for life-long. [Infection or Vaccine] 2.PASSIVE ACQUIRED IMMUNITY : It is acquired through the transfer of antibody or activated T-cells from immune host and is short lived usually last for few months.

8.  COMPONENTS OF ACQUIRED IMMUNITY : 1.B Lymphocytes 2.T Lymphocytes

9. B Lymphocytes : o Mature and develop in Bone Marrow. o B Lymphocytes are so called because they are bone marrow derived. o B Lymphocytes named after their site of origin in bursa of Fabricius in birds or in bone marrow in humans form the basis for humoral immunity by their production of Immunoglobulin. o Do not have any subtype. o Represents components of Humoral Immunity. o Recognize antigens on the surface of bacteria and viruses. o It have shorter life-spans. o 20% of blood lymphocytes are B cells.

10. o Have 2 types: 1. Plasma cells o 2. Memory cells o Do not act against tumor cells or transplants. o Defend against bacteria and viruses in blood stream or lymph. o IgM and IgD molecules serves as antigen specific receptor.

11. T Lymphocytes : o T cells originate in Bone marrow and mature in thymus. o Mature cells occurs inside lymph nodes. o Recognize viral antigens on outside of the infected cells. o It have longer life-spans. o They lack surface antigens. o 2 types :1. T helper cells 2. T cytotoxic cells o T lymphocytes migrate to thymus and undergo their maturation. o Invovled in Cell Mediated Immunity. o 80% of the blood lymphocytes are T cells. o Move t site of infection.

12. o Act against tumor cells or transplants. o Have an inhibitory effect on immune system. o Defend against pathogens including viruses, fungi that enter the cells in the body. o TCR serve as antigen specific receptor.

13. T Helper cells : o Also called as CD4 + cells are the type of T cell that play important role in Immune System. o Secrete cytokines to regulate other cells in Immune System and present antigens to B cells. T Cytotoxic cells : o Is a type of Immune cells that can kill certain cells including Foreign cells, Cancer cells and cell infected with a virus. o Contain CD8 receptor. o Destroy virus-infected cells and tumor cells. o CD8 receptors can recognize antigen presented with MHCI class molecules.

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