Innate Immunity & Inflammation Quiz
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Questions and Answers

Which of the following best describes the role of physical barriers in the innate immune system?

  • They chemically neutralize pathogens in the bloodstream.
  • They consist of immune cells that directly attack pathogens.
  • They provide a first line of defense to prevent pathogen entry. (correct)
  • They regulate the immune response through cytokine release.

Which cell type is primarily responsible for the phagocytosis of pathogens in tissues?

  • Natural killer (NK) cells
  • Mast cells
  • Dendritic cells
  • Macrophages (correct)

What distinguishes innate immune cells from T and B cells in terms of their origin?

  • Innate immune cells are exclusively found in bone marrow.
  • Innate immune cells originate from myeloid lineage. (correct)
  • Innate immune cells are derived from lymphoid lineage.
  • Innate immune cells develop only in lymph nodes.

Which of the following is NOT considered a chemical barrier in innate immunity?

<p>Tight junctions in epithelial cells (D)</p> Signup and view all the answers

Which part of the lymphatic system is NOT primarily involved in immune response?

<p>Heart (D)</p> Signup and view all the answers

Which type of immunity is characterized as being non-specific and the body's first defense against pathogens?

<p>Innate immunity (B)</p> Signup and view all the answers

Which soluble factor is specifically mentioned as contributing to innate immunity?

<p>Alpha- and beta-defensins (A)</p> Signup and view all the answers

What role do lymphoid tissues primarily serve in the immune system?

<p>They intercept invading microbes before they enter circulation. (A)</p> Signup and view all the answers

What is a primary characteristic of the innate immune response?

<p>It involves a rapid and non-specific reaction. (A)</p> Signup and view all the answers

Which type of receptors do innate immune cells use to recognize pathogens?

<p>Pattern Recognition Receptors (PRRs) (B)</p> Signup and view all the answers

What triggers the process of phagocytosis in innate immune cells?

<p>Recognition of PAMPs via PRRs (A)</p> Signup and view all the answers

Which type of PRR is known to recognize components of viruses?

<p>RIG-1 like receptors (RLRs) (B)</p> Signup and view all the answers

What role do Damage-Associated Molecular Patterns (DAMPs) play in the immune response?

<p>They signal the presence of cellular damage. (A)</p> Signup and view all the answers

What is the primary function of phagocytosis in innate immunity?

<p>To encapsulate and digest pathogens. (D)</p> Signup and view all the answers

How do innate immune cells engage with the adaptive immune system?

<p>By presenting antigens using MHC Class II molecules. (B)</p> Signup and view all the answers

Commonly, which cells are classified as professional phagocytes in the innate immune system?

<p>Macrophages, Neutrophils, and Dendritic cells (A)</p> Signup and view all the answers

What leads to the increased vascular diameter during inflammation?

<p>Increased permeability of endothelial cells. (A)</p> Signup and view all the answers

What is a consequence of the accumulation of toxic byproducts in phagocytic cells?

<p>Induction of apoptosis (C)</p> Signup and view all the answers

Which statement about the timing of the innate immune response is accurate?

<p>It typically initiates within minutes to hours of exposure. (C)</p> Signup and view all the answers

What do Toll-like Receptors (TLRs) primarily recognize?

<p>Common structural components of pathogens (C)</p> Signup and view all the answers

How do inflammatory signals contribute to innate immunity?

<p>They promote tissue repair and healing. (B)</p> Signup and view all the answers

What occurs as a result of opsonization in the immune response?

<p>Enhanced adhesion of phagocytes to pathogens. (C)</p> Signup and view all the answers

Which of the following molecules would most likely function as a DAMP?

<p>Actin released from damaged cells (A)</p> Signup and view all the answers

Flashcards

Innate Immunity

The body's first line of defense against pathogens, a non-specific immune response.

Pathogen

An organism that can cause disease.

Physical Barriers

The body's first line of defense against pathogens, such as skin, mucous membranes, and cilia.

Chemical Barriers

Substances that harm or kill pathogens, like stomach acid and antimicrobial peptides.

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Lymphatic System

Network of vessels and tissues that collect and filter fluid (lymph) throughout the body.

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Myeloid Lineage

Cells that make up much of the innate immune system.

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Phagocytic Cells

Cells that engulf and destroy pathogens, like macrophages and neutrophils.

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Lymphocytes

Cells of the immune system that are part of the adaptive immune response, and are concentrated in lymphatic tissue.

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Innate immune response

A rapid, non-specific immune response that occurs within minutes to hours of encountering a pathogen or danger signal.

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Pattern Recognition Receptors (PRRs)

Receptors on innate immune cells that recognize specific molecular patterns (PAMPs) on pathogens.

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Pathogen-Associated Molecular Patterns (PAMPs)

Molecules that are common to many pathogens and recognized by PRRs.

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Toll-like Receptors (TLRs)

A type of PRR that plays a crucial role in recognizing different pathogen components.

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Phagocytosis

The process by which immune cells engulf and destroy pathogens.

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Inflammation

A response to tissue damage or infection that involves increased blood flow, cell recruitment, and removal of foreign material.

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Damage-Associated Molecular Patterns (DAMPs)

Molecules released from damaged cells that trigger inflammation.

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Sterile inflammation

Inflammation that occurs in the absence of a pathogen, triggered by damaged tissue.

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Opsonization

The process of making a pathogen more readily ingested by phagocytes.

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Professional phagocytes

Immune cells specialized in phagocytosis, such as macrophages, neutrophils, and dendritic cells.

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Cytokines

Signaling molecules that mediate inflammation and communicate between immune cells.

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Vasodilation

Widening of blood vessels, a key step in inflammation.

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MHC Class II

A protein that presents antigens to cells of the adaptive immune system. (Innate response preparation)

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Adaptive immunity

A later, antigen-specific immune response with memory that leads to efficient responses upon subsequent exposure to familiar pathogens.

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Phagolysosome

Structure formed by the fusion of a phagosome (containing pathogen) with a lysosome (containing digestive enzymes).

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Study Notes

Innate Immunity & Inflammation

  • Innate immunity is the first line of defense against pathogens.
  • A pathogen is an organism that can cause disease, but not all pathogens cause disease. Pathogens can be cellular or acellular. Hosts can include bacteria and phages, plants, animals, and humans.

Barriers

  • Physical barriers: Tight junctions in skin, eyelids, epithelial cells, cilia, and mucous membrane surfaces.
  • Chemical/organismal barriers: Commensal bacteria, sweat, saliva, tears, urine, stomach acid, and antimicrobial peptides (e.g., defensins).

Lymphatic System

  • The lymphatic system is a network of vessels that carries lymph (clear liquid).
  • It's not a closed system, unlike the cardiovascular system.
  • Lymphocytes are concentrated in lymph nodes and lymphoid tissues (spleen, thymus, tonsils, etc.).
  • Lymphoid tissues intercept invading microbes before they enter circulation.

Cells of the Innate Immune Response

  • Innate immune cells are derived from the myeloid lineage.
  • They include monocytes, macrophages, dendritic cells, natural killer (NK) cells, mast cells, and granulocytes (basophils, eosinophils, neutrophils).
  • Some subsets of T cells also have innate immune properties.
  • These cells respond within minutes-hours of recognizing pathogens/danger signals.
  • Response is rapid but non-specific and lacks memory.

Innate Immune Cell Recognition

  • Innate immune cells have Pattern Recognition Receptors (PRRs).
  • Four major PRR types are Toll-like Receptors (TLRs), NOD-like Receptors (NLRs), C-type lectin receptors (CLRs), and RIG-I-like receptors (RLRs).
  • PRRs recognize Pathogen-Associated Molecular Patterns (PAMPs) – proteins, peptides, carbohydrates, nucleic acids of pathogens. PRRs may also recognize other compounds.
  • Cellular response is determined based on PRR-PAMP interaction. Multiple PRRs can work simultaneously.
  • Multiple checks and balances exist to ensure appropriate response.
  • Innate cells also recognize Damage-Associated Molecular Patterns (DAMPs) – DNA, mtDNA, ATP, ADP, actin, amyloid-beta, etc.
  • DAMPs are produced from damaged cells; in contrast to apoptosis, necrosis is inflammatory.

Sterile Inflammation

  • Sterile inflammation occurs in the absence of a pathogen, due to damaged cells (nonspecific).
  • This occurs in many systemic inflammatory diseases.

Phagocytosis

  • Phagocytosis is used to eliminate pathogens.
  • It begins with PRR-PAMP interactions (opsonization).
  • Actin rearrangement encapsulates the pathogen (phagosome).
  • Lysosomes fuse with phagosome (phagolysosome) to break down the pathogen.
  • Contents are released.
  • Contents of the pathogen can be presented to the adaptive immune system via MHC.

Adaptive Immunity

  • Adaptive immunity is covered in a separate lecture.

Inflammation

  • Inflammation is a response to cellular damage, characterized by increased blood flow, increased capillary permeability, edema (fluid accumulation), and immune cell migration into tissue. The cardinal signs of inflammation are related to vasodilation of arterioles & capillaries and increased capillary permeability.

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Description

Test your knowledge on the innate immune system and its role in inflammation. This quiz covers key concepts such as barriers to pathogens, the lymphatic system, and the cells involved in innate immunity. Ideal for students studying immunology or related fields.

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