Immune Response Quiz

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Questions and Answers

What role does C3b play in the immune response?

Destroys pathogens directly

Inhibits inflammation

Suppresses the immune response

Aids in phagocytosis (correct)

Which of the following components primarily attracts phagocytes during an immune response?

C5a (correct)

C5b

C3b

C3a

What is one of the effects of the combination of C3a and C5a?

Activating the complement system

Inhibiting phagocytosis

Causing inflammation (correct)

Inducing apoptosis in immune cells

Which chemical primarily intensifies the effects of histamine and kinins during the inflammatory response?

Prostaglandins Signup and view all the answers

C3b is responsible for splitting which of the following components?

C5 into C5a and C5b Signup and view all the answers

What sequence of events follows the formation of a blood clot during inflammation?

Margination of phagocytes occurs before diapedesis Signup and view all the answers

Which of the following statements about leukotrienes is correct?

They increase blood vessel permeability and assist in phagocytic attachment. Signup and view all the answers

Which of the following statements is true regarding the effects of C3a and C5a?

They promote the attraction of phagocytes. Signup and view all the answers

During the inflammatory response, what role do kinins play?

They lead to vasodilation and increased permeability of blood vessels. Signup and view all the answers

Which structure is primarily affected during the process of diapedesis?

Endothelial cells Signup and view all the answers

What is the primary function of the thoracic duct in the lymphatic system?

Transporting lymph fluid back to the bloodstream Signup and view all the answers

Which lymphatic structure is primarily responsible for the maturation of T lymphocytes?

Thymus Signup and view all the answers

Where does the right lymphatic duct primarily drain lymphatic fluid?

Right subclavian vein Signup and view all the answers

Which of the following organs is NOT directly involved in the lymphatic system's immune functions?

Small intestine Signup and view all the answers

What role do lymph nodes play in the lymphatic system?

Filtering lymph fluid and trapping pathogens Signup and view all the answers

What is the primary action of sulfamethoxazole in bacterial metabolism?

It inhibits the synthesis of dihydrofolic acid. Signup and view all the answers

Which of the following correctly describes the mechanism of trimethoprim?

It acts as a structural analog of a portion of dihydrofolic acid. Signup and view all the answers

What role do echinocandins play in antifungal treatments?

They inhibit the synthesis of -glucan. Signup and view all the answers

What is the function of amphotericin B in antifungal therapy?

It disrupts fungal cell membranes. Signup and view all the answers

Which statement characterizes the action of antiviral treatments discussed?

They target entry/fusion and genome integration. Signup and view all the answers

Which component forms the backbone of peptidoglycan in gram-positive bacteria?

N-acetylmuramic acid Signup and view all the answers

What differentiates semisynthetic penicillins from natural penicillins?

They have a modified common nucleus. Signup and view all the answers

Which of the following varieties of cephalosporins has the broadest spectrum?

Third-generation Signup and view all the answers

What is the primary action of penicillinase on penicillins?

It converts them into non-functional products. Signup and view all the answers

What is the role of clavulanic acid when used in combination with antibiotics?

Inhibits the activity of penicillinase. Signup and view all the answers

Which antibiotic is considered a 'last line' treatment against antibiotic-resistant strains?

Vancomycin Signup and view all the answers

What characteristic is shared by first-generation cephalosporins?

Primarily effective against gram-positive bacteria. Signup and view all the answers

Which of the following statements about the structure of penicillin is true?

It contains a common nucleus. Signup and view all the answers

What characterizes a secondary (memory) immune response?

It happens after a second exposure to the same pathogen. Signup and view all the answers

Which type of immunity involves the injection of antibodies directly into an individual?

Artificially acquired passive immunity Signup and view all the answers

What is an implication of the similarity between eukaryotic microbes and human cells in terms of treatment?

Treatment options may have low selectivity and high toxicity. Signup and view all the answers

Which of the following best describes bacteriostatic antimicrobial activity?

It inhibits the growth of bacteria without killing them. Signup and view all the answers

Which combination type of drug interactions reduces the effectiveness of a treatment?

Antagonistic interactions Signup and view all the answers

What particular challenge is posed by viral infections in terms of treatment?

Viruses utilize host cells for their growth and replication. Signup and view all the answers

What is a function of bactericidal drugs?

They directly kill bacteria. Signup and view all the answers

Which of the following antibiotics primarily targets cell wall synthesis in bacteria?

Bacitracin Signup and view all the answers

Study Notes

First Line of Defense: Skin and Mucous Membranes

Skin acts as a physical barrier, consisting of tightly packed cells with keratin, a protective protein.
Mucous membranes trap microbes.
Ciliary escalator transports trapped microbes away from lungs.
Secretions like tears, saliva, urine, and vaginal secretions help wash away invaders.
Normal microbiota plays a role in preventing pathogens from colonizing.
Chemical factors such as low pH, lysozyme, and fungistatic fatty acids in sebum also contribute to the first line of defense.

Physical Factors

Skin's epidermis is a tightly packed layer of cells with keratin.
Mucous membranes trap microbes with mucus.
Ciliary escalator transports trapped microbes from the lungs.
Secretions like tears, saliva, urine, and vaginal secretions wash away invaders.

Chemical Factors

Sebum (sebaceous glands) contains fungistatic fatty acids.
Skin has a low pH (3-5) due to fatty acids and lactic acid.
Perspiration, tears, saliva, and urine contain lysozyme.
Gastric juice has a low pH (1.2-3.0) due to HCl and enzymes.
Vaginal secretions have a low pH (3-5) due to lactic acid bacteria.

Second Line of Defense

Phagocytes: neutrophils, eosinophils, dendritic cells, and macrophages.
Inflammation.
Fever.
Antimicrobial substances.

Phagocytosis

Phagocytosis is the ingestion of microbes or particles by a cell, performed by phagocytes.
Phagocytes bind to microbes (chemotaxis and adherence).
Microbes are engulfed (ingestion).
Microbe is digested in a phagolysosome.
Waste materials are discharged.

Inflammation

Inflammation is a reaction to tissue damage.
Key symptoms include redness, swelling (edema), pain, and heat.
Cytokines like TNF-a activate acute-phase proteins, amplifying the response.
Three stages: vasodilation, phagocyte migration/phagocytosis, and tissue repair.
Chemicals like histamine, kinins, prostaglandins, leukotrienes, and cytokines are released from damaged cells.

Fever

Fever is a systemic reaction to infection.
The hypothalamus normally maintains a temperature of 37°C.
Phagocytes release cytokines (e.g., IL-1, TNF).
Cytokines trigger prostaglandin release, resetting the hypothalamus to a higher temperature.
Body increases rate of metabolism, promotes shivering, and constricts blood vessels (chills).
Increased body temperature decreases when vasodilation and sweating occur.

Antimicrobial Substances

Complement system is a group of serum proteins that work in a cascade.
Activated by antibodies or antigens directly.
Leads to inflammation, cytolysis (cell lysis), and opsonization.
Interferons are antiviral proteins.
Iron-binding proteins sequester iron needed for microbial growth.
Antimicrobial peptides directly kill microbes.

The Lymphatic System

Transports fluid back to the bloodstream, recycles plasma proteins, delivers leukocytes, and filters out invaders.
Contains lymph fluid, lymphatic vessels, and lymphatic tissue (nodes and organs like spleen, thymus).
Lymph capillaries collect interstitial fluid (lymph) and return it to the bloodstream.

Adaptive Immunity

Adaptive immunity: induced resistance to specific pathogens.
Differentiates into humoral (antibody-mediated) and cellular (cell-mediated) immunity.
B cells mature in bone marrow, producing antibodies targeting specific antigens.
T cells mature in the thymus, performing cell-mediated immune responses via T cell receptors, attacking intracellular pathogens.

Antibodies and Antigens

Antigens are substances that trigger an immune response (antibodies or sensitized T cells).
Antibodies (immunoglobulins) interact with epitopes (antigenic determinants) on antigens.
Haptens are small antigens that need a carrier molecule to trigger an immune response.

B Cells

B cells are activated by T-helper cells (dependent antigens) or by antigens directly (independent antigens).
Activated B cells differentiate into plasma cells producing antibodies and memory cells.
Clonal selection ensures specific antibodies are produced for each antigen.
Clonal deletion removes B cells that react with self-antigens to prevent autoimmune responses.

T Cells

T cells respond to antigens presented by antigen-presenting cells (APCs).
T helper (TH) cells activate other immune cells (e.g., macrophages, cytotoxic T cells).
Cytotoxic T (TC) cells directly kill infected cells.
Regulatory T (Treg) cells suppress immune responses.
Activated macrophages have enhanced phagocytosis, and Natural Killer (NK) cells destroy cells that lack MHC I.

Antibody-Dependent Cell-Mediated Cytotoxicity (ADCC)

Antibodies tag target cells for destruction by other immune cells (e.g., macrophages or eosinophils).
Important for eliminating large parasites that cannot be engulfed.

Immunological Memory

The primary response occurs after initial exposure to an antigen; the secondary response is faster.
Memory cells are formed during the primary response, allowing a faster and stronger secondary response if the same antigen is encountered again.

Types of Adaptive Immunity

Naturally acquired active immunity occurs after an infection.
Naturally acquired passive immunity occurs when antibodies are transferred from mother to offspring.
Artificially acquired active immunity occurs after vaccination.
Artificially acquired passive immunity occurs after injection of antibodies.

Antibiotic Resistance

Antibiotic misuse leads to resistance mutants.
Outdated antibiotics, inappropriate use (common colds),using antibiotics in animal feed, and incomplete prescription regimens contribute to the problem.
The overuse of triclosan contributes to multidrug-resistant bacteria.
Resistance genes often reside on plasmids or transposons and can move between bacteria.

Antimicrobial Drugs

Bactericidal drugs directly kill microbes.
Bacteriostatic drugs prevent microbial growth.
Synergistic interactions amplify drug efficacy.
Antagonistic interactions weaken drug efficacy.
Mechanisms of action may target cell walls, protein synthesis, nucleic acid synthesis, or cell membranes. Polyenes, azoles, and allylamines inhibit ergosterol synthesis while glycoproteins and echinocandins inhibit synthesis of-glucan. Quinolones and fluoroquinolones inhibit DNA gyrase; sulphonamides inhibit folic acid synthesis. Inhibitors of cell wall synthesis like penicillin, cephalosporins, and vancomycin targets cell wall synthesis.

Antiviral Drugs

Entry inhibitors prevent viruses from entering cells; fusion inhibitors prevent viral envelope fusion.
Nucleoside analogs block viral DNA synthesis .
Interferons prevent viral spread to new cells.

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Description

Test your knowledge on the immune response and its components. This quiz covers key topics such as the roles of C3b, C3a, and C5a, phagocyte attraction, and the effects of various chemicals during inflammation. Perfect for students studying immunology.