Immune System Overview

Study Notes

The immune system is a complex network of cells, tissues, and organs that defend the body against infection and disease.
It consists of two main branches: innate immunity and adaptive immunity.

Provides immediate, non-specific defense against pathogens.
Involves physical barriers (skin, mucous membranes), cellular components (neutrophils, macrophages), and chemical mediators (complement system).
Recognizes pathogens through pattern recognition receptors (PRRs).

Provides specific, long-term defense against pathogens.
Involves activation of T-cells and B-cells, which recognize and respond to specific antigens.
Involves antibody production and immune memory.

T-cells (T-lymphocytes):
- Recognize and respond to antigens presented by antigen-presenting cells (APCs).
- Types: CD4+ (helper T-cells), CD8+ (cytotoxic T-cells), and regulatory T-cells.
B-cells (B-lymphocytes):
- Produce antibodies against specific antigens.
- Activate to become plasma cells, which secrete antibodies.
Dendritic cells:
- Recognize and process antigens, presenting them to T-cells.
- Activate T-cells and initiate immune response.
Macrophages:
- Engulf and digest foreign particles and pathogens.
- Present antigens to T-cells.
Neutrophils:
- Destroy pathogens through phagocytosis and degranulation.

Activation:
- Recognition of antigens by PRRs or antigen-presenting cells.
- Activation of T-cells and B-cells.
Effector:
- Elimination of pathogens through antibody production and cell-mediated cytotoxicity.
Regulation:
- Regulation of immune response through cytokines, regulatory T-cells, and immune suppression.

Autoimmune disorders:
- Immune system attacks self-antigens.
- Examples: rheumatoid arthritis, lupus, and multiple sclerosis.
Immunodeficiency disorders:
- Impaired immune function.
- Examples: HIV/AIDS, primary immunodeficiency diseases.
Allergies:
- Overactive immune response to harmless antigens.
- Examples: hay fever, food allergies, and asthma.

A complex network of cells, tissues, and organs that defends the body against infection and disease.

Provides immediate, non-specific defense against pathogens.
Involves physical barriers (skin, mucous membranes) and cellular components (neutrophils, macrophages).
Recognizes pathogens through pattern recognition receptors (PRRs).
Chemical mediators include the complement system.

Provides specific, long-term defense against pathogens.
Involves activation of T-cells and B-cells, which recognize and respond to specific antigens.
Involves antibody production and immune memory.

T-cells (T-lymphocytes):
- Recognize and respond to antigens presented by antigen-presenting cells (APCs).
- Types: CD4+ (helper T-cells), CD8+ (cytotoxic T-cells), and regulatory T-cells.
B-cells (B-lymphocytes):
- Produce antibodies against specific antigens.
- Activate to become plasma cells, which secrete antibodies.
Dendritic cells:
- Recognize and process antigens, presenting them to T-cells.
- Activate T-cells and initiate immune response.
Macrophages:
- Engulf and digest foreign particles and pathogens.
- Present antigens to T-cells.
Neutrophils:
- Destroy pathogens through phagocytosis and degranulation.

Activation:
- Recognition of antigens by PRRs or antigen-presenting cells.
- Activation of T-cells and B-cells.
Effector:
- Elimination of pathogens through antibody production and cell-mediated cytotoxicity.
Regulation:
- Regulation of immune response through cytokines, regulatory T-cells, and immune suppression.

Autoimmune disorders:
- Immune system attacks self-antigens.
- Examples: rheumatoid arthritis, lupus, and multiple sclerosis.
Immunodeficiency disorders:
- Impaired immune function.
- Examples: HIV/AIDS, primary immunodeficiency diseases.
Allergies:
- Overactive immune response to harmless antigens.
- Examples: hay fever, food allergies, and asthma.