Overview of Immunology

Overview of Immunology

• Study of the immune system and its functions in protecting the body from disease.
• Involves understanding how the body detects and responds to pathogens (bacteria, viruses, fungi, and parasites).

Components of the Immune System

1. Cells of the Immune System

   • Lymphocytes
     • B cells: Produce antibodies, responsible for humoral immunity.
     • T cells:
       • Helper T cells (CD4+): Assist B cells and other immune cells.
       • Cytotoxic T cells (CD8+): Kill infected or cancerous cells.
   • Phagocytes
     • Macrophages: Engulf and digest pathogens.
     • Neutrophils: First responders to infection.
   • Natural Killer (NK) Cells: Recognize and destroy infected or cancerous cells.

2. Organs of the Immune System

   • Primary Lymphoid Organs
     • Bone Marrow: Site of B cell maturation.
     • Thymus: Site of T cell maturation.
   • Secondary Lymphoid Organs
     • Lymph Nodes: Filter lymph and site of immune response activation.
     • Spleen: Filters blood and activates immune responses.
     • Mucosal-associated lymphoid tissue (MALT): Protects mucosal surfaces.

Immune Responses

1. Innate Immunity

   • First line of defense: Rapid response (minutes to hours).
   • Non-specific: General defense mechanisms (skin, phagocytes, fever, inflammation).
   • Key components:
     • Physical barriers (skin, mucous membranes).
     • Chemical barriers (secretions, antimicrobial peptides).

2. Adaptive Immunity

   • Specific response: Slower activation (days to weeks).
   • Memory: Remembers pathogens for faster response upon re-exposure.
   • Key components:
     • Antibody-mediated immunity (B cells).
     • Cell-mediated immunity (T cells).

Immunological Memory

• Development of memory B and T cells after initial exposure to a pathogen.
• Provides long-lasting protection against previously encountered pathogens.

Antibodies

• Proteins produced by B cells that neutralize pathogens.
• Types of antibodies:
  • IgG: Most abundant, crosses placenta.
  • IgA: Found in mucosal areas, breast milk.
  • IgM: First antibody produced in response to infection.
  • IgE: Involved in allergic reactions.
  • IgD: Function still not fully understood.

Vaccination

• Stimulates adaptive immunity by exposing the immune system to a harmless form of a pathogen.
• Types of vaccines:
  • Live attenuated: Weakened form of the pathogen.
  • Inactivated: Killed pathogen.
  • Subunit: Contains pieces of the pathogen.
  • mRNA: Encodes a part of the pathogen to elicit an immune response.

Immune Disorders

1. Immunodeficiency

   • Primary: Genetic defects (e.g., SCID).
   • Secondary: Acquired (e.g., HIV/AIDS, malnutrition).

2. Autoimmunity

   • Immune system mistakenly attacks the body's own cells (e.g., lupus, rheumatoid arthritis).

3. Allergies

   • Hypersensitive immune response to harmless substances (e.g., pollen, peanuts).

Conclusion

• Immunology is crucial for understanding health and disease.
• Advances in immunology lead to better vaccines and therapies for various diseases.

Overview of Immunology

• Immunology focuses on the immune system's function in disease protection.
• Understanding the body's detection and response mechanisms to pathogens, including bacteria, viruses, fungi, and parasites.

Components of the Immune System

• Cells of the Immune System

  • Lymphocytes
    • B cells: Generate antibodies; central to humoral immunity.
    • T cells:
      • Helper T cells (CD4+): Support B cells and coordinate immune responses.
      • Cytotoxic T cells (CD8+): Eliminate infected or cancerous cells.
  • Phagocytes
    • Macrophages: Engulf and digest pathogens.
    • Neutrophils: Act as first responders to infection.
  • Natural Killer (NK) Cells: Target and destroy infected or tumor cells.

• Organs of the Immune System

  • Primary Lymphoid Organs
    • Bone Marrow: Site of B cell maturation.
    • Thymus: Site where T cells mature.
  • Secondary Lymphoid Organs
    • Lymph Nodes: Filter lymph; where immune responses are activated.
    • Spleen: Filters blood; key in activating immunity.
    • Mucosal-associated lymphoid tissue (MALT): Guards mucosal surfaces.

Immune Responses

• Innate Immunity

  • Acts as the first line of defense with a rapid response timeframe (minutes to hours).
  • Non-specific, employing general mechanisms such as skin, phagocytes, fever, and inflammation.
  • Key components include physical barriers (e.g., skin) and chemical barriers (e.g., antimicrobial peptides).

• Adaptive Immunity

  • Characterized by a specific response; activation occurs slower (days to weeks).
  • Develops immunological memory for quicker responses to previously encountered pathogens.
  • Involves antibody-mediated (B cells) and cell-mediated (T cells) immunity.

Immunological Memory

• Memory B and T cells arise after initial exposure, providing lasting protection against previously encountered pathogens.

Antibodies

• Antibodies are proteins generated by B cells to neutralize pathogens.
• Types of antibodies include:
  • IgG: Most prevalent; crosses the placenta.
  • IgA: Present in mucosal areas and breast milk.
  • IgM: The first antibody produced during infection.
  • IgE: Associated with allergic reactions.
  • IgD: Role is not fully understood.

Vaccination

• Vaccines stimulate adaptive immunity by presenting a harmless form of a pathogen.
• Types of vaccines:
  • Live attenuated: Weakened pathogen.
  • Inactivated: Killed pathogen.
  • Subunit: Contains portions of the pathogen.
  • mRNA: Delivers genetic instructions to prompt an immune response.

Immune Disorders

• Immunodeficiency
  • Primary: Genetic abnormalities (e.g., Severe Combined Immunodeficiency - SCID).
  • Secondary: Acquired conditions (e.g., HIV/AIDS, malnutrition).
• Autoimmunity
  • Occurs when the immune system mistakenly attacks the body’s own cells (e.g., lupus, rheumatoid arthritis).
• Allergies
  • Result from hypersensitive immune responses to non-harmful substances (e.g., pollen, nuts).

Conclusion

• Immunology plays a vital role in understanding human health and diseases.
• Advancements in this field have led to improved vaccines and therapies for a range of diseases.

This quiz covers the fundamentals of immunology, focusing on the immune system's components and their roles in protecting the body against diseases. You will learn about various immune cells, their functions, and the organs that support immune responses.