The Immune System

What are antigens and how do they trigger an immune response?

Antigens are molecules, usually proteins, that can generate an immune response when detected by the body.

What are the main types of cells or substances that antigens can help the immune system identify?

Antigens are used by the immune system to identify pathogens, abnormal body cells, toxins, and cells from other individuals of the same species.

How many main stages are there in the immune response process?

There are four main stages in the immune response.

What is the main function of phagocytes?

Engulfing pathogens through phagocytosis.

How do phagocytes recognize pathogens?

By identifying foreign antigens on the pathogens.

What happens to the pathogen once engulfed by a phagocyte?

It is contained in a phagocytic vacuole within the phagocyte's cytoplasm.

What organelle within the phagocyte helps break down the pathogen?

Lysosome, which contains lysozymes.

How do phagocytes activate other immune system cells?

By presenting the pathogen's antigens on their surface.

How do T-cells become activated?

T-cells become activated when their receptor proteins bind to complementary antigens presented by phagocytes.

What is the role of helper T-cells (Th cells)?

Helper T-cells release chemical signals that activate and stimulate phagocytes, cytotoxic T-cells, and B-cells.

What is a phagocyte and what is its function?

A phagocyte is a type of white blood cell that carries out phagocytosis, which is the engulfment of pathogens.

How do phagocytes work in response to a pathogen?

Phagocytes recognize foreign antigens on pathogens, engulf the pathogen, contain it in a phagocytic vacuole, fuse a lysosome containing lysozymes to break down the pathogen, and present the pathogen's antigens to activate other immune system cells.

What are B-cells and what is their role in the immune response?

B-cells, also known as B-lymphocytes, are white blood cells covered with antibodies that bind antigens to form an antigen-antibody complex.

How do B-cells become activated and what do they divide into?

B-cells become activated when the antibody on their surface binds to a complementary shaped antigen, and with the help of substances released from helper T-cells, they divide into plasma cells.

How do plasma cells contribute to the immune response?

Plasma cells produce large amounts of antibodies specific to a particular antigen.

What are monoclonal antibodies?

Antibodies secreted by plasma cells that are specific to a single antigen.

What is the significance of antibodies having two binding sites?

Antibodies can bind to two pathogens simultaneously, leading to agglutination.

How do antibodies contribute to the destruction of pathogens?

Antibodies bind to pathogens, leading to agglutination and subsequent phagocytosis by phagocytes.

What determines the specificity of an antibody?

The variable regions of the antibody, which form the antigen binding sites, determine its specificity.

What are the two main components of the immune response?

Cellular and Humoral

What cells are involved in the cellular response of the immune system?

• T cells (T lymphocytes)

• B cells (B lymphocytes)

• Macrophages

• Natural killer (NK) cells

• Dendritic cells

What components make up the humoral response of the immune system?

• The humoral response of the immune system involves B cells, antibodies, and cytokines. B cells produce antibodies that target pathogens, while cytokines help regulate the immune response.

How do T-cells and B-cells interact in the immune response?

T-cells and B-cells interact in the immune response by recognizing antigens. T-cells activate B-cells to produce antibodies, while B-cells present antigens to T-cells for further activation.

What is the primary immune response?

The immune response when an antigen enters the body for the first time.

What is the difference between cellular and humoral responses in the immune system?

Cellular response involves T-cells and phagocytes, while humoral response involves B-cells and antibodies.

How do memory cells contribute to immunity?

Memory cells remain in the body for a long time, allowing for a quicker and more effective response to a second infection.

What is the Secondary Immune Response characterized by?

A quicker, stronger immune response

How do Memory B-cells contribute to the Secondary Immune Response?

They divide into plasma cells that produce the right antibody to the antigen.

What happens to Memory T-cells during the Secondary Immune Response?

They divide into the correct type of T-cells to kill the cell carrying the antigen.

What is a key advantage of the Secondary Immune Response?

It often eliminates the pathogen before symptoms appear.