Immune response

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== Immune Response ==

The immune response is the body's defense mechanism against pathogens, such as bacteria, viruses, and other harmful agents. It involves a complex network of cells, tissues, and organs that work together to identify and neutralize foreign invaders.

Components of the Immune System[edit | edit source]

The immune system is divided into two main components: the innate immune system and the adaptive immune system.

Innate Immune System[edit | edit source]

The innate immune system is the body's first line of defense and responds to pathogens in a generic way. It includes physical barriers like the skin and mucous membranes, as well as immune cells such as macrophages, neutrophils, and natural killer cells.

Adaptive Immune System[edit | edit source]

The adaptive immune system is more specialized and can remember specific pathogens for faster responses in future encounters. It involves lymphocytes, including B cells and T cells. B cells produce antibodies that neutralize pathogens, while T cells destroy infected cells.

Stages of the Immune Response[edit | edit source]

The immune response can be divided into several stages:

Recognition[edit | edit source]

The immune system recognizes pathogens through antigens, which are molecules found on the surface of pathogens. Antigen-presenting cells (APCs) such as dendritic cells capture and present these antigens to T cells.

Activation[edit | edit source]

Once antigens are recognized, the immune system is activated. T cells proliferate and differentiate into various subtypes, including helper T cells and cytotoxic T cells. Helper T cells assist in activating B cells, while cytotoxic T cells kill infected cells.

Response[edit | edit source]

Activated B cells produce antibodies that bind to antigens, marking them for destruction by other immune cells. Cytotoxic T cells directly attack and destroy infected cells.

Memory[edit | edit source]

After the pathogen is eliminated, some T and B cells become memory cells. These cells remain in the body and provide a faster and more efficient response if the same pathogen is encountered again.

Disorders of the Immune System[edit | edit source]

The immune system can sometimes malfunction, leading to various disorders:

Autoimmune diseases: The immune system mistakenly attacks the body's own cells. Examples include rheumatoid arthritis and lupus.
Immunodeficiency: The immune system is weakened and cannot effectively respond to infections. Examples include HIV/AIDS and SCID.
Allergies: The immune system overreacts to harmless substances, such as pollen or pet dander.