Immune System Overview

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Questions and Answers

Which of the following best describes the primary lymphoid organs?

Lymph nodes and bone marrow

Tonsils and lymph nodes

Bone marrow and thymus (correct)

Spleen and MALT

What is a key function of macrophages in the immune system?

Maturation into neutrophiles

Activation of lymphoid progenitor cells

Antigen processing and presentation (correct)

Secretion of immunoglobulins

Which of the following correctly classifies immune cells into innate or acquired types?

Monocytes are innate; T cells are acquired (correct)

B cells are innate; Macrophages are acquired

Natural killer cells are acquired; T cells are innate

Neutrophils are acquired; Monocytes are innate

Which cytokines primarily influence the proliferation and differentiation of lymphocytes?

IL-3 and IL-7 Signup and view all the answers

What is the primary role of neutrophils in the immune response?

Mediating inflammatory reactions Signup and view all the answers

Which of the following components are found on macrophages?

Class I and II MHC molecules Signup and view all the answers

What primarily distinguishes the myeloid lineage of immune cells?

Originating in the bone marrow and giving rise to phagocytes Signup and view all the answers

Which feature is characteristic of tissue resident macrophages?

Arise from yolk sac and fetal liver precursors Signup and view all the answers

Which of the following cytokines is primarily involved in the innate immune response?

IL-1 Signup and view all the answers

What is the primary function of antigen-presenting cells (APCs)?

Capture and present antigens to lymphocytes Signup and view all the answers

Which cell type is considered the most important APC for activating naive T cells?

Dendritic cells Signup and view all the answers

Which of the following is NOT a function of macrophages?

Deleting memory T cells Signup and view all the answers

Which type of innate immune cell is primarily associated with allergic responses?

Mast cells Signup and view all the answers

What is the result of macrophages presenting antigens to helper T lymphocytes?

Production of cytokines Signup and view all the answers

Which of the following statements about cytokines is CORRECT?

Cytokines can have both innate and acquired immune functions. Signup and view all the answers

Which cells present antigens to helper T cells, playing a key role in antibody responses?

Macrophages Signup and view all the answers

Study Notes

Immune System Tissues

The primary lymphoid organs include the bone marrow and thymus.
Secondary lymphoid organs include lymph nodes, spleen, tonsils, mucosa-associated lymphoid tissues (MALT) of the gastrointestinal tract and respiratory tract.

Immune System Cells

Immune system cells develop from pluripotent stem cells in the bone marrow.
Differentiation is influenced by soluble mediators (cytokines) like IL-7, IL-3, and colony stimulating factors.
Lymphoid and myeloid series represent two distinct cell lineages.

Phagocytes

Phagocytes are cells capable of engulfing and destroying foreign particles or cells.
Neutrophils are the most abundant circulating white blood cells, actively involved in the early stages of inflammation.
Mononuclear phagocytes include monocytes and tissue-resident macrophages.
- Monocytes circulate in the blood and differentiate into macrophages upon entering tissues.
- Macrophages originate from precursors in the yolk sac and fetal liver during fetal development.
- Macrophages possess receptors for Fc portion of IgG, complement component C3b, and express MHC class I and II.
- Macrophages play a crucial role in phagocytosis, antigen processing and presentation, cytokine production (e.g., IL-1, IL-6, IL-12, TNF-α), and complement synthesis.
Mast cells, basophils, and eosinophils are involved in allergic reactions and parasitic infections.
- Mast cells are present in skin and mucosal epithelia, containing granules filled with histamine.
- Basophils are granulocytes involved in allergic responses.
- Eosinophils exert cytotoxic actions against parasites and contribute to allergic reactions.

Antigen-Presenting Cells (APCs)

APCs capture antigens, display them to lymphocytes, and provide signals that stimulate lymphocyte activation.
Dendritic cells are the most important APCs for activating naive T cells, playing a critical role in innate responses to infections and linking innate and adaptive immune responses.
Macrophages present antigens to helper T lymphocytes at infection sites, triggering helper T cell activation and further macrophage activation.
B cells present antigens to helper T cells, essential for collaborating with helper T cells to generate antibody responses to protein antigens.

Key Points about APC Functions

Phagocytosis is an innate immune function.
Antigen processing and presentation is mainly an acquired immune function but also plays a role in innate immunity.
Cytokine production and complement synthesis are both innate and acquired immune functions depending on the specific cytokines or complement components involved.
Dendritic cells are the primary antigen-presenting cells.

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Description

Explore the key components of the immune system, including its tissues, cells, and the roles of phagocytes. This quiz covers the primary and secondary lymphoid organs, immune cell differentiation, and the function of neutrophils and macrophages. Test your understanding of how these components work together to protect the body.