Immunology Study Notes: Innate Immunity

Definition: First line of defense; non-specific response to pathogens.
Components:
- Physical Barriers: Skin, mucous membranes, secretions (e.g., saliva, tears).
- Cellular Components:
  - Phagocytes: Macrophages, neutrophils; engulf and digest pathogens.
  - Natural Killer (NK) Cells: Target and destroy infected or cancerous cells.
- Molecules:
  - Cytokines: Signaling proteins that mediate immune responses.
  - Complement System: Series of proteins that enhance the immune response by opsonization and lysis of pathogens.
Mechanisms:
- Inflammatory Response: Redness, heat, swelling, and pain as the body responds to injury or infection.
- Phagocytosis: Process by which phagocytes engulf and destroy pathogens.
Characteristics:
- Immediate response (minutes to hours).
- Lacks memory; maintains consistent response regardless of pathogen exposure.

Definition: Specific response to pathogens, develops over time, and has memory.
Components:
- Lymphocytes:
  - B Cells: Produce antibodies targeting specific antigens.
  - T Cells:
    - Helper T Cells (CD4+): Activate B cells and cytotoxic T cells.
    - Cytotoxic T Cells (CD8+): Directly kill infected or cancerous cells.
Mechanisms:
- Antibody Production: B cells undergo clonal selection and expansion to produce specific antibodies.
- Cell-Mediated Immunity: T cells recognize and attack infected cells.
Characteristics:
- Delayed response (days to weeks) after first exposure.
- Memory: Subsequent exposures lead to a faster and stronger response.
Types of Adaptive Immunity:
- Humoral Immunity: Involves B cells and antibody production.
- Cell-Mediated Immunity: Involves T cells targeting infected or abnormal cells.

Innate Immunity: Rapid, non-specific response; physical barriers, phagocytes, NK cells.
Adaptive Immunity: Slower, specific response; B and T cells with memory for future infections.

Functions as the body's first line of defense against pathogens through a non-specific response.
Physical Barriers: Includes skin, mucous membranes, and secretions like saliva and tears that prevent pathogen entry.
Cellular Components:
- Phagocytes: Macrophages and neutrophils play a crucial role in engulfing and digesting harmful pathogens.
- Natural Killer (NK) Cells: Specialize in targeting and destroying infected cells and cancer cells.
Molecular Components:
- Cytokines: Proteins that facilitate communication and regulation of immune responses among cells.
- Complement System: Comprises proteins that boost immune responses through pathogen opsonization and lysis.
Mechanisms:
- Inflammatory Response: Characterized by redness, heat, swelling, and pain as the body coordinates a defense against injury or infection.
- Phagocytosis: A vital process where phagocytes engage and eliminate pathogens.
Characteristics:
- Provides an immediate response within minutes to hours.
- Lacks immunological memory, ensuring a uniform response to repeated pathogen exposure.

Develops a specific immune response against pathogens over time, allowing for a memory-based response.
Components:
- Lymphocytes:
  - B Cells: Responsible for producing antibodies that specifically target antigens.
  - T Cells: Include two main types:
    - Helper T Cells (CD4+): Facilitate the activation of B cells and other T cells.
    - Cytotoxic T Cells (CD8+): Directly kill cells that are infected or malfunctioning.
Mechanisms:
- Antibody Production: B cells undergo a process of clonal selection and expansion to generate specific antibodies against antigens.
- Cell-Mediated Immunity: T cells identify and attack compromised cells within the body.
Characteristics:
- Initiates a delayed immune response that takes days to weeks after the first pathogen exposure.
- Exhibits memory; subsequent encounters with the same pathogen trigger faster and more robust immune reactions.
Types of Adaptive Immunity:
- Humoral Immunity: Involves B cells and the generation of antibodies.
- Cell-Mediated Immunity: Involves T cells targeting and eliminating infected or abnormal cells.