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The Immune System - includes all parts or organs of the body that help in the recognition and destruction of foreign materials.Passive immunization (patient is given ready preformed antibodies form of immunotherapy) Active immunization (patient is vaccinated with a killed or attenuated microbe to form antibodies by itself.Lymphoid organs can be divided as: 1- Primary Lymphoid Organs 2- Secondary Lymphoid Organs Primary Lymphoid Organs include (Thymus and Bone marrow) T & B Cells Secondary Lymphoid Organs include (Tonsil,Lymph node, Spleen, Peyer's patches, Appendix and Tissue lymphatic ) The immune system is typically divided into two categories innate (non specific) and adaptive or acquired (specific) First-Line Defenses (Non Specific defence) (Innate Immune System ) -The body's first line of defense against pathogens uses mostly physical and chemical barriers such as; Skin - acts as a barrier to invasion.Examole of second line of defence; Phagocytic cells (WBCs & Macrophages) This will result in what is called an Inflammatory response (Cardinal signs of inflammation) causes : Redness - due to capillary dilation resulting in increased blood flow Heat - due to capillary dilation resulting in increased blood flow Swelling - due to passage of plasma from the blood stream into the damaged tissue Pain - due mainly to tissue destruction and, to a lesser extent, swelling.Classification of Antibodies (Immunoglobulins) Immunoglobulin M (IgM)

• Immunoglobulin G (IgG)
• Immunoglobulin A (IgA)
• Immunoglobulin D (IgD)
• Immunoglobulin E (IgE) Humoral and Cellular Immunity Humoral and Cellular Immunity In the humoral immune response (B lymphocytes), soluble proteins called antibodies (immunoglobulins).For each type of pathogen, the immune system produces cells that are specific for that particular pathogen (Antibodies) Active immunity : is the resistance (synthesis of antibodies) developed by an individual, as a result of an antigenic stimulus .Adaptive (Acquired) immunity(Specific Mechanisms of Defense) (antibody formation) Adaptive immunity refers to antigen-specific immune response.Immunity is divided to; Active immunity : it is organism antibodies production which formed by pathogenic induction.Leukocytes (WBCs) are central to all immune responses.

The Immune System - includes all parts or organs of the body that help in the recognition and destruction of foreign materials.
Immunity refers to protection against infection.
The immune system is the collection of Organs (cells, tissues and molecules) that functions to defend us against infectious microbes.
The coordinated reaction of the immune system against infections (and other foreign substances) is known as the immune response.
A number of morphologically and functionally diverse organs and tissues function in the development of immune responses.
Leukocytes (WBCs) are central to all immune responses.
Lymphoid organs can be divided as:
1- Primary Lymphoid Organs
2- Secondary Lymphoid Organs
Primary Lymphoid Organs include (Thymus and Bone marrow) T & B Cells
Secondary Lymphoid Organs include (Tonsil,Lymph node, Spleen, Peyer’s patches, Appendix and Tissue lymphatic )
The immune system is typically divided into two categories innate (non specific) and adaptive or acquired (specific)
First-Line Defenses (Non Specific defence) (Innate Immune System )
-The body's first line of defense against pathogens uses mostly physical and chemical barriers such as;
Skin – acts as a barrier to invasion.
Sweat – has chemicals which can kill different pathogens.
Tears - have lysozyme which has powerful digestive abilities that render antigens harmless.
Saliva – also has lysozyme.
Mucus -can trap pathogens, which are then sneezed, coughed, washed away, or destroyed by chemicals.
Stomach Acid – destroys pathogen
Second-Line Defenses (Non Specific defence)
If a pathogen is able to get past the body's first line of defense, and an infection starts, the body can rely on its second line of defense.
Examole of second line of defence; Phagocytic cells (WBCs & Macrophages)
This will result in what is called an Inflammatory response (Cardinal signs of inflammation) causes :
Redness - due to capillary dilation resulting in increased blood flow
Heat - due to capillary dilation resulting in increased blood flow
Swelling – due to passage of plasma from the blood stream into the damaged tissue
Pain – due mainly to tissue destruction and, to a lesser extent, swelling.
Antigen
A substance capable of inducing a specific immune response(antibody production) is called an antigen.
A protein (immunoglobulin) that recognizes a particular antigen and binds specifically to it is called an ‘antibody’.
Antibodies are produced by T cells & B cells.
Adaptive (Acquired) immunity(Specific Mechanisms of Defense) (antibody formation)
Adaptive immunity refers to antigen-specific immune response. The adaptive immune response is more complex than the innate.
Third-Line Defenses- Sometimes the second line of defense is still not enough and the pathogen is then heading for the body's last line of defense, the immune system.
The immune system recognizes, attacks, destroys, and remembers each pathogen that enters the body. It does this by making specialized cells and antibodies that render the pathogens harmless.
For each type of pathogen, the immune system produces cells that are specific for that particular pathogen (Antibodies)
Active immunity : is the resistance (synthesis of antibodies) developed by an individual, as a result of an antigenic stimulus .
Immunity is divided to;
Active immunity : it is organism antibodies production which formed by pathogenic induction.
Passive immunity: It is a ready-made antibodies resistance from an other organism that is transferred to a recipient.
Here, the recipient’s immune system plays no active role. There is no antigenic stimulus. Instead, pre-formed antibodies are administered.
Classification of Antibodies (Immunoglobulins)
Immunoglobulin M (IgM)

• Immunoglobulin G (IgG)


• Immunoglobulin A (IgA)


• Immunoglobulin D (IgD)


• Immunoglobulin E (IgE)
  Humoral and Cellular Immunity
  Humoral and Cellular Immunity
  In the humoral immune response (B lymphocytes), soluble proteins called antibodies (immunoglobulins). This antibodies are secreted by plasma cells that are derived from B-lymphocytes (B cells).
  In the cellular immune response (T lymphocytes), cells called cytotoxic T- lymphocytes kill cells that display foreign motifs on their surfaces.
  Passive immunization (patient is given ready preformed antibodies form of immunotherapy)
  Active immunization (patient is vaccinated with a killed or attenuated microbe to form antibodies by itself.
  DISORDERS OF THE IMMUNE SYSTEM
  1- Hypersensitivity Reactions 2- Autoimmunity 3- Immunodeficiencies