Biology of the Immune System

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Questions and Answers

What role do biological barriers play in the immune system?

They directly kill pathogens.

They prevent initial infections by outcompeting pathogens. (correct)

They enhance the responses of phagocytes.

They neutralize toxins produced by bacteria.

Which of the following is NOT a physiological barrier to infection?

Coughing

Diarrhoea

Sneezing

Defensins (correct)

What is the function of complement proteins in the immune response?

To promote bacterial adhesion.

To facilitate pathogen lysis. (correct)

To produce essential vitamins.

To prevent the growth of commensal flora.

Which of these is an example of a chemical barrier to infection?

Low pH Signup and view all the answers

How do phagocytes contribute to the immune response?

By engulfing and destroying pathogens. Signup and view all the answers

What can result from dysregulation of innate immune mechanisms?

Development of autoimmune disorders. Signup and view all the answers

Which component is a characteristic function of antimicrobial molecules?

Killing bacteria through proteolysis. Signup and view all the answers

What does normal flora do in terms of immune defense?

Occupies attachment sites to outcompete pathogens. Signup and view all the answers

What type of immunity is transferred from mother to fetus through IgG?

Natural Passive Immunity Signup and view all the answers

Which organ is responsible for the maturation of T-cells?

Thymus Signup and view all the answers

What is a primary function of lymph nodes in the immune system?

To filter lymph fluid and assist in immune responses Signup and view all the answers

Which of the following provides artificial passive immunity?

Monoclonal Antibodies Signup and view all the answers

What is the role of the spleen in the immune system?

Filter blood and remove damaged blood cells Signup and view all the answers

Which component of the immune system acts as the body's first line of defense against ingested or inhaled pathogens?

Tonsils and Adenoids Signup and view all the answers

Which type of immune cells are produced in the bone marrow?

Leukocytes, including WBCs Signup and view all the answers

What type of immunity is provided through pooled human immunoglobulin?

Artificial Passive Immunity Signup and view all the answers

What role does the MHC play in the immune system?

It stimulates the adaptive immune system. Signup and view all the answers

Which of the following are Class I HLA genes?

HLA-A Signup and view all the answers

What is the significance of matching HLA markers in organ transplantation?

It minimizes the risk of rejection. Signup and view all the answers

Which cells primarily express Class II HLA genes?

B cells, dendritic cells, and macrophages Signup and view all the answers

What type of antigens do Class I HLA proteins present?

Endogenous antigens Signup and view all the answers

Where are the genes encoding HLA located in humans?

Chromosome 6 Signup and view all the answers

What aspect does HLA polymorphism influence?

Susceptibility to autoimmune diseases Signup and view all the answers

How are alleles of the HLA gene designated?

With a combination of letters and numbers Signup and view all the answers

What is the main function of T Regulatory (Treg) Cells?

Suppress excessive immune responses and maintain tolerance Signup and view all the answers

Which pathway of complement-mediated lysis requires antibodies to bind to the target bacterium?

Classical Complement Pathway Signup and view all the answers

What is the role of cytokines in immune responses?

Regulating immune cell behavior by promoting or inhibiting responses Signup and view all the answers

How does the Alternative Complement Pathway initiate the complement cascade?

By C3 directly binding to bacteria Signup and view all the answers

Which option describes a feature of the Membrane Attack Complex (MAC)?

It perforates membranes of Gram-negative bacteria Signup and view all the answers

What is the purpose of maintaining homeostasis in immune responses?

To avoid damaging healthy tissues Signup and view all the answers

Which of the following statements about the Lectin Pathway is true?

It specifically binds to proteins containing mannose residues Signup and view all the answers

What is meant by the 'balancing act' in inflammation regulation?

Balancing between adequate responses to pathogens and preventing excessive inflammation Signup and view all the answers

What is the primary cause of Transfusion-Related Acute Lung Injury (TRALI)?

Donor antibodies reacting with recipient leukocytes Signup and view all the answers

Which symptom is NOT associated with Haemolytic Disease of Newborn (HDN)?

Decreased maternal blood pressure Signup and view all the answers

What type of antibodies are produced during the first pregnancy in Rh incompatibility?

IgM antibodies Signup and view all the answers

What is the primary effect of maternal anti-D antibodies on foetal red blood cells during subsequent Rh+ pregnancies?

Destruction of foetal Rh+ RBCs Signup and view all the answers

What is the mechanism through which severe complications arise in a foetus affected by HDN?

Sensitization followed by IgG anti-D production Signup and view all the answers

Which of the following is a recommended preventative treatment for Rh-negative mothers?

Administration of Rh immunoglobulin Signup and view all the answers

What does a positive result in a Direct Coombs' Test indicate?

Patient's RBCs have antibodies attached to them Signup and view all the answers

Which of the following is a potential effect of foetal anaemia caused by HDN?

Severe Foetal Hydrops Signup and view all the answers

Which of the following causes can compromise immune function?

HIV/AIDS Signup and view all the answers

What characterizes monoclonal gammopathies?

Abnormal proliferation of a single clone of plasma cells Signup and view all the answers

Which type of allergic reaction is primarily mediated by IgE antibodies?

Type 1 Signup and view all the answers

In which type of allergic reaction do antibodies target cell surface antigens?

Type 2 Signup and view all the answers

What is the primary mechanism of damage in Type 3 allergic reactions?

Immune complex deposition Signup and view all the answers

Which of the following is an example of an allergic disease specifically related to Type 4 hypersensitivity?

Contact dermatitis Signup and view all the answers

What type of immunoglobulin is primarily involved in Type 1 allergic reactions?

IgE Signup and view all the answers

What is a hallmark symptom of Type 1 allergic reactions?

Immediate release of mediators like histamine Signup and view all the answers

What distinguishes Type 2 allergic reactions from Type 3?

Location of antigens Signup and view all the answers

Which of the following is an example of a condition associated with Type 2 allergic reactions?

Goodpasture's syndrome Signup and view all the answers

What type of immune response is triggered in Type 4 allergic reactions?

Delayed T-cell-mediated response Signup and view all the answers

Which of the following allergens could induce an allergic response?

Environmental pollen Signup and view all the answers

Which cells are primarily involved in the immediate phase of Type 1 allergic reactions?

Basophils and Mast cells Signup and view all the answers

What role does IL-4 play in Type 1 allergic reactions?

Promotes B-cell switching to IgE production Signup and view all the answers

Study Notes

Clinical Immunology Summary

Credit for the document goes to TeachMe Physiology, Bitesized Immunology, Seminars & Lectures, and other senior summaries.
The immune system is the body's defense against pathogens, infections, and harmful substances. This system is composed of a variety of organs, cells, proteins, and tissues.
Types of immunity include active and passive immunity.
Active immunity is when the body's immune system mounts an adaptive immune response in response to exposure to an antigen. This response forms memory cells that rapidly recognize and respond again to the antigen. Natural and artificial active immunity fall under this type.
Natural active immunity occurs when there is exposure to a disease, and the body subsequently creates a memory response.
Artificial active immunity occurs as a result of vaccination. The individual is exposed to a weakened form of pathogen or antigens of that pathogen to encourage the adaptive immune response and formation of memory cells.
Passive immunity relies on antibodies introduced to a non-immune individual. This response is short-lived. Examples include receiving antibodies from a mother to a foetus or an individual.
Natural passive immunity: IgG from mother to foetus, IgA in breast milk.
Artificial passive immunity: antibodies in plasma or blood products. Pooled human immunoglobulin, administered in various ways, given to donors or those recovering from diseases. Monoclonal antibodies.
Organs of the immune system include bone marrow, thymus, lymph nodes, and spleen.
Other immune structures include tonsils, adenoids, and mucosa-associated lymphoid tissue (MALT).
Leukocytes (white blood cells) are immune cells circulating in the blood and lymphatic system. The five main types are neutrophils, eosinophils, basophils, monocytes, and lymphocytes.
Antibodies are proteins produced by B-cells that recognize and neutralize pathogens. They tag pathogens for destruction by other immune cells.
Antigens are foreign substances causing an immune response.
Molecules of the immune system include cytokines (small proteins for cell signaling), chemokines, interferons, and TNF-alpha/beta (Tumor Necrosis Factor).
Cells of the immune system include Natural killer (NK) cells, T cells (CD4+ helper and CD8+ cytotoxic cells), and B cells (antibody production).
MHC are proteins for antigen presentation. Class I MHC is present on virtually all nucleated cells, presenting endogenous antigens to CD8+ T cells. Class II MHC is present primarily on antigen-presenting cells (APCs), presenting exogenous antigens to CD4+ T cells. HLA = Human Leukocyte Antigen.
Innate immunity: present at birth, non-specific, no long-term memory, includes physical barriers (skin, mucus membranes, secretions), physiological barriers (vomiting, coughing, sneezing), chemical barriers (low pH, antimicrobial molecules, enzymes), and biological barriers (normal flora).
Cellular barriers: phagocytes (macrophages, neutrophils)
Humoral factors: complement proteins
Acquired immunity: developed over time, specific, long-term memory, involves B and T lymphocytes, antibodies, and immunological memory.

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Description

Test your knowledge on the biological barriers and mechanisms of the immune system. This quiz covers physiological and chemical barriers, the role of cells and organs, and types of immunity. Challenge yourself to see how well you understand immune responses!