Immune System Overview

Study Notes

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

Provides immediate, non-specific defense against infection.
Includes physical barriers (skin, mucous membranes), cellular components (neutrophils, macrophages), and chemical factors (complement system).

T cells (T lymphocytes):
- Recognize and eliminate infected cells or produce chemical signals to activate other immune responses.
- Divided into two subtypes: CD4+ (T helper cells) and CD8+ (cytotoxic T cells).
B cells (B lymphocytes):
- Produce antibodies (immunoglobulins) to neutralize or remove pathogens.
- Can also activate other immune responses.
Dendritic cells: Antigen-presenting cells that activate T cells and B cells.
Macrophages: Engulf and digest foreign particles and microorganisms.
Neutrophils: Phagocytic cells that engulf and digest foreign particles and microorganisms.

Humoral immunity: Involves the production of antibodies by B cells to neutralize or remove pathogens.
Cell-mediated immunity: Involves the activation of T cells to eliminate infected cells or produce chemical signals.

Autoimmune diseases: The immune system attacks self-antigens, leading to diseases such as rheumatoid arthritis and lupus.
Immunodeficiency diseases: The immune system is weakened, making the body more susceptible to infections, such as HIV/AIDS.
Hypersensitivity reactions: Overactive immune responses, such as allergies and anaphylaxis.

The immune system is a complex network that defends the body against infection and disease, comprising two main branches: innate and adaptive.

Provides immediate, non-specific defense against infection, including:
- Physical barriers (skin, mucous membranes)
- Cellular components (neutrophils, macrophages)
- Chemical factors (complement system)

Provides specific, long-term immunity against specific pathogens, involving:
- Activation of T cells and B cells
- Antigen processing and presentation
- Production of antibodies

T cells (T lymphocytes):
- Recognize and eliminate infected cells or produce chemical signals
- Divided into two subtypes: CD4+ (T helper cells) and CD8+ (cytotoxic T cells)
B cells (B lymphocytes):
- Produce antibodies (immunoglobulins) to neutralize or remove pathogens
- Can also activate other immune responses
Dendritic cells:
- Antigen-presenting cells that activate T cells and B cells
Macrophages:
- Engulf and digest foreign particles and microorganisms
Neutrophils:
- Phagocytic cells that engulf and digest foreign particles and microorganisms

Humoral immunity:
- Involves production of antibodies by B cells to neutralize or remove pathogens
Cell-mediated immunity:
- Involves activation of T cells to eliminate infected cells or produce chemical signals

The immune system's ability to distinguish between self and non-self, involving regulation of immune responses to prevent autoimmune diseases.

Autoimmune diseases:
- The immune system attacks self-antigens, leading to diseases such as rheumatoid arthritis and lupus
Immunodeficiency diseases:
- The immune system is weakened, making the body more susceptible to infections, such as HIV/AIDS
Hypersensitivity reactions:
- Overactive immune responses, such as allergies and anaphylaxis