Components of the Immune System Quiz

Components of the Immune System

• The immune system is responsible for defending the body against pathogens.
• It differentiates between "self" and "non-self" to avoid attacking the body's own cells.
• The immune system uses innate and acquired immune responses.

The Big Picture

• The primary immune response is the initial reaction to a pathogen.
• Antigen-presenting cells (APCs) activate T cells.
• B cells differentiate into plasma cells, which produce antibodies.
• Memory cells form for faster response to subsequent infections.

Objectives

• Students need to distinguish between innate and acquired immunity.
• They need to identify and describe the cellular components of the immune system.
• Students need to describe lymphoid organs, structures, and associated cells and functions.
• They need to explain lymphocyte recirculation's role in antigen trapping and immunity development.

Importance of the Immune System

• The immune system defends against infections.
• It plays a role in vaccination and immunization.
• It defends against tumors.
• It works as a barrier against transplant rejection.
• It plays a critical role in immunotherapy against infections and cancer.

Challenges to the Immune System

• Specificity
• Diversity
• Memory
• Specialization
• Resolution
• Non-reactivity to self
• Mobility

Immune "Defense"

• The human body is constantly under attack by pathogens.
• This defense extends to pathogens like viruses, bacteria, fungi, parasites, pollen, dander and food or water.
• It includes defense against internal threats like autoimmune diseases and cancer.

How does the immune system recognize potential invaders?

• Recognizing "self" versus "non-self" is a fundamental immune function.
• The system is trained to avoid reacting against the body's own cells.
• Innate and acquired immune responses work together.
  • Innate response is nonspecific.
  • Acquired response is specific.

Two Types of Immunity

• Innate immunity is always available and includes basic elements like body surfaces, mucous membranes, reflexes, and phagocytic cells like macrophages.
• Acquired immunity is developed after birth and composed of specialized cells, present only in vertebrates, and only active if contacted with a particular antigen. It's crucial in fighting off infection as opposed to the non-specific immune system.

How does our body generate such an effective, elaborate system?

• This question seeks to understand the mechanism behind the immune system's complex workings.

Hematopoiesis

• All blood cells originate from hematopoietic stem cells, found in the bone marrow.
• Hematopoiesis is the process of blood cell development.
• Blood cells develop in specific types; myeloid and lymphoid.
• Myeloid Lineage: Important in innate immunity with several functions; granulocytes, macrophages, dendritic cells, and mast cells.
• Lymphoid Lineage: B cells from the bone marrow and mature into plasma cells to produce antibodies for specific antigens. T cells mature in the thymus and have antigen-specific receptors to help with antigen recognition. Natural killer (NK) cells are present in the bone marrow and perform immunity.

The Myeloid Lineage

• Granulocytes are important in innate immunity.
• Macrophages are phagocytic immune cells.
• Dendritic cells are antigen-presenting cells.
• Neutrophils, Eosinophils, and Basophils are types of granulocytes.
• Basophils and Mast cells are involved in the innate immune response.

Antigen-Presenting Cells

• Antigen-presenting cells (APCs) are crucial in linking innate and adaptive immunity.
• Dendritic cells, macrophages, and B lymphocytes are APCs.
• APCs display antigens on their surfaces for T cell recognition.

Macrophages

• Macrophages are widely distributed throughout the reticuloendothelial system.
• They are derived from blood monocytes.
• Macrophages play a crucial role in innate immune responses, like phagocytosis and antigen presentation.

Lymphocytes

• Lymphocytes are distributed throughout specialized lymphoid tissues.
• Lymphocytes originate in bone marrow, and later mature (T cells) in the thymus.
• Lymph picks up debris, pathogens, and APCs that have already phagocytosed pathogens.
• The lymph is then transported, via the lymphatic vessels, to the lymph nodes where an immune response may be generated.

Lymphocyte Recirculation

• Lymphocytes recirculate through the body to encounter pathogens in tissues.
• Brings pathogens to lymph nodes called the draining lymph node, where a specific immune response may be generated.
• Lymphocytes and lymph return to the blood via lymphatic vessels.

The Lymph Node

• Lymph nodes are small organs (<1 cm) that filter lymph.
• Afferent lymphatic vessels bring lymph from tissues to lymph nodes, and then one large efferent lymph vessel goes to the lymph nodes.
• During infections, pathogens, debris, and antigen-presenting cells (APCs) arrive in the lymph.

More of the Big Picture

• Activated T2 cells produce TGF-β and IL-10. These factors influence immune response.
• Activated T1 cells produce IFN-γ. This factor inhibits the proliferation of T2 cells.

How Vaccines Work

• Vaccines contain antigens from pathogens.
• The body, after exposure to a vaccine, mounts an immune response.
• The immune response results in antibodies toward the antigen in the vaccine.
• The adaptive immunity process happens for the specific pathogen.

The Immune Response

• Primary responses involve IgM antibodies.
• Secondary responses (re-exposure to the antigen) involve IgG/IgA antibodies, higher levels and stronger binding.
• T cells are also important.

Tetanus Study

• Review D2L material on Tetanus Immunity Tutorial.
• Read the Tetanus Tutorial Plan.
• Complete the pre-test.

This quiz covers the essential components and functions of the immune system. Students will distinguish between innate and acquired immunity, identify cellular components, and explain the role of lymphoid organs and lymphocyte recirculation. Test your knowledge on how the immune system defends against infections!