Immune System: Defense Mechanisms, Cells, and Responses

What is the goal of the First Line of Defense in the immune system?

To stop pathogens from entering the body.

What are the physical barriers in the First Line of Defense?

Skin and mucous membranes.

What role do cilia play in the immune system?

They help move mucus out of the lungs to trap and remove pathogens.

What is the main function of the Second Line of Defense (Innate Immunity)?

To attack anything foreign in a fast and nonspecific manner.

What are PAMPs in the context of the immune system?

Pathogen-Associated Molecular Patterns recognized by the immune system.

What are the key components of Innate Immunity?

Phagocytes, inflammation, fever, and antimicrobial proteins.

What is the goal of the Third Line of Defense (Adaptive Immunity)?

To target specific pathogens with memory for faster response upon re-exposure.

What types of cells are involved in Adaptive Immunity?

B cells and T cells.

What are Toll-like receptors (TLRs)?

Surface receptors found on immune cells that recognize PAMPs and trigger immune responses.

What is the role of cytokines in the immune system?

They are protein messengers that control cell communication, inflammation, and immune activation.

What happens during inflammation?

Tissue damage triggers histamine release, leading to blood vessel dilation, swelling, and migration of white blood cells.

What is phagocytosis?

The process by which immune cells engulf and destroy pathogens.

What is the complement system?

A group of proteins in blood that enhance immune responses through opsonization, inflammation, and cell lysis.

What is the difference between an antigen and an antibody?

An antigen is a piece of a pathogen that triggers an immune response, while an antibody is a protein that binds to an antigen.

What are the main actions of antibodies when they bind to antigens?

Neutralization, agglutination, opsonization, and activation of complement.

What are the five classes of antibodies?

IgG, IgM, IgA, IgE, and IgD.

What is the primary immune response characterized by?

A slow response with low antibody levels.

How does the secondary immune response differ from the primary response?

It is faster and stronger due to the presence of memory cells.

What are the four types of immunity?

Natural active, artificial active, natural passive, and artificial passive.

What is the function of lymph nodes in the lymphatic system?

To filter pathogens from lymph fluid.

What is the role of macrophages in the immune system?

They perform phagocytosis and present antigens to activate T cells.

What is the significance of memory cells in the immune response?

They provide a faster and stronger response upon re-exposure to the same pathogen.

What happens during a cytokine storm?

Excessive cytokine production leads to severe inflammation and can be dangerous.

What is the role of Natural Killer (NK) cells?

They kill abnormal cells without needing antigen recognition.