Overview of Immunology Basics

Definition: Immunology is the branch of biomedical science that studies the immune system and its functions in protecting the body against pathogens.

Cells
- Lymphocytes: Key players in the immune response.
  - B cells: Produce antibodies.
  - T cells: Regulate immune responses or kill infected cells.
- Phagocytes: Cells that engulf and digest pathogens (e.g., macrophages, neutrophils).
- Dendritic cells: Antigen-presenting cells that activate T cells.
Organs
- Primary Lymphoid Organs:
  - Bone marrow: Site of B cell maturation.
  - Thymus: Site of T cell maturation.
- Secondary Lymphoid Organs:
  - Spleen: Filters blood and activates immune responses.
  - Lymph nodes: Filter lymph and support immune cell activation.

Innate Immunity:
- Non-specific defense mechanisms present at birth.
- Includes barriers (skin, mucous membranes), phagocytes, and inflammatory responses.
Adaptive Immunity:
- Specific defense mechanisms developed in response to exposure to pathogens.
- Involves B and T lymphocytes; can develop memory for faster response to future infections.

Recognition: Immune system identifies pathogens through antigens.
Activation: Lymphocytes are activated and proliferate.
Response: Effector mechanisms eliminate pathogens (e.g., antibody production, cell-mediated killing).
Resolution: Homeostasis is restored, and immune cells that are no longer needed undergo apoptosis or become memory cells.

Antigens: Substances that trigger an immune response (e.g., proteins on pathogens).
Antibodies:
- Y-shaped proteins produced by B cells that specifically bind to antigens to neutralize or mark them for destruction.
- Classes include IgG, IgM, IgA, IgE, and IgD.

Allergies: Hypersensitive reactions to non-harmful antigens.
Autoimmune Diseases: Immune system mistakenly attacks healthy cells (e.g., lupus, rheumatoid arthritis).
Immunodeficiency Disorders: Compromised immune responses (e.g., HIV/AIDS).

A method of stimulating adaptive immunity by exposing the immune system to a weakened or inactivated form of a pathogen.
Promotes the development of memory cells for faster response upon re-exposure.

Understanding immunology is crucial for developing vaccines, treatments for diseases, and enhancing immune health. The balance between adequate immune response and avoidance of overreaction (autoimmunity) is vital for maintaining health.

The study of the immune system and its role in defending the body against disease-causing organisms.

Cells:
- Lymphocytes:
  - Responsible for specific immune responses.
  - B cells: Produce antibodies to neutralize pathogens.
  - T cells: Regulate immune responses or directly kill infected cells.
- Phagocytes: Engulf and destroy pathogens.
  - Examples: macrophages and neutrophils.
- Dendritic cells: Present antigens to T cells, initiating an immune response.
Organs:
- Primary Lymphoid Organs:
  - Bone marrow: Site of B cell maturation.
  - Thymus: Site of T cell maturation.
- Secondary Lymphoid Organs:
  - Spleen: Filters blood; activates immune responses.
  - Lymph nodes: Filter lymph; support immune cell activation.

Innate Immunity:
- Non-specific defense mechanisms present at birth.
- Includes barriers like skin and mucous membranes, phagocytes, and inflammatory responses.
Adaptive Immunity:
- Specific defense mechanisms that develop in response to exposure to pathogens.
- Involves B and T lymphocytes; can develop memory for faster responses to future infections.

Recognition: Immune system identifies pathogens through antigens.
Activation: Lymphocytes are activated and proliferate.
Response: Effector mechanisms eliminate pathogens (e.g., antibody production, cell-mediated killing).
Resolution: Homeostasis is restored; immune cells that are no longer needed undergo apoptosis or become memory cells.

Antigens: Substances that trigger an immune response (e.g., proteins on pathogens).
Antibodies:
- Y-shaped proteins produced by B cells that specifically bind to antigens.
- Functions: neutralize pathogens or mark them for destruction.
- Classes include IgG, IgM, IgA, IgE, and IgD.

Allergies: Hypersensitive reactions to non-harmful antigens.
Autoimmune Diseases: Immune system mistakenly attacks healthy cells (e.g., lupus, rheumatoid arthritis).
Immunodeficiency Disorders: Compromised immune responses (e.g., HIV/AIDS).

Stimulates adaptive immunity by exposing the immune system to a weakened or inactivated form of a pathogen.
Promotes the development of memory cells for faster responses upon re-exposure.

Understanding immunology is crucial for developing vaccines, treatments for diseases, and enhancing immune health.
Maintaining a balance between an effective immune response and avoiding overreaction (autoimmunity) is essential for health.