Immune System and Infection Transmission Quiz

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Questions and Answers

Which transmission mode occurs when a mother passes an infection to her child during pregnancy?

Blood-borne transmission

Inhalation

Vertical transmission (correct)

Vector borne transmission

What is the primary characteristic of innate antigen-nonspecific immune defenses?

They are only effective through vaccination.

They rely exclusively on antibodies.

They are specific to particular antigens.

They provide immediate response to pathogens. (correct)

Which of the following is NOT considered a first line of defense against infection?

Sneezing

Vomiting

Natural killer cells (correct)

Coughing

What is the role of lactoferrin in the body?

It acts as an immunomodulator and has antibacterial properties. Signup and view all the answers

What kind of infection transmission occurs during delivery?

Perinatal infection Signup and view all the answers

What is the primary goal of the complement system in the immune response?

To clear bacterial cells Signup and view all the answers

Which cells are responsible for engulfing pathogens during innate immunity?

Macrophages Signup and view all the answers

What is a characteristic of inflammation?

Localized physical changes such as redness and swelling Signup and view all the answers

What role do microbial toxins play in pathogenic infections?

They directly harm tissues Signup and view all the answers

What type of toxin is secreted by bacteria and possesses enzymatic activity?

Exotoxin Signup and view all the answers

How do leukocytes contribute to the immune response during inflammation?

By ingesting and destroying bacteria Signup and view all the answers

Which component is not involved in the innate immune response?

Antibody production Signup and view all the answers

What triggers the inflammatory response in the body?

Pathogen invasion and tissue damage Signup and view all the answers

What is the primary difference between infection and infectious disease?

Infection can occur without causing disease. Signup and view all the answers

Which type of bacteria are known to cause disease only in individuals with preexisting conditions?

Opportunistic pathogens Signup and view all the answers

How do strict primary pathogens differ from opportunistic pathogens?

Strict primary pathogens can cause disease in healthy individuals. Signup and view all the answers

What do commensal bacteria do in relation to the host?

They live on the host without causing any harm. Signup and view all the answers

What factor does NOT contribute to infectious disease caused by pathogens?

Commensal bacteria preventing other bacterial growth. Signup and view all the answers

What describes carriers in the context of bacterial infections?

They have no symptoms but can spread pathogens. Signup and view all the answers

Which of the following is NOT a source of exogenous infections?

Healthy individuals Signup and view all the answers

What does immunopathogenesis refer to?

Part of the disease process involving the immune response. Signup and view all the answers

Which statement about infection is correct?

Not all infections result in disease. Signup and view all the answers

What defines saprophytes in the context of microbial life?

Microbes that grow in soil and on dead organic matter. Signup and view all the answers

What is a characteristic feature of exotoxins?

They can be cytotoxic and may cause disease through various mechanisms. Signup and view all the answers

Which class of exotoxins is characterized by membrane disruption and pore formation?

Cytolytic toxins Signup and view all the answers

How are A-B toxins structured?

They are composed of two separate components, A and B. Signup and view all the answers

What effect do superantigens have on the immune system?

They cause a marked but ineffective activation of the immune system. Signup and view all the answers

Which statement about endotoxins is true?

Endotoxins are found in the outer layers of Gram-negative bacteria. Signup and view all the answers

What is the main function of pore-forming toxins (PFTs)?

To insert pores into the plasma membrane that lead to cell death. Signup and view all the answers

Which type of toxins are primarily associated with the symptoms of diseases like diphtheria and tetanus?

Exotoxins Signup and view all the answers

What is a significant characteristic of thermolabile proteins?

They are highly antigenic and can cause specific immune responses. Signup and view all the answers

Study Notes

Bacterial Pathogenesis Mechanisms

Bacteria cause disease through infection, which involves the growth and multiplication of bacteria within or on the body, potentially leading to disease development.
Infection does not always result in disease.
The host's defense mechanisms play a crucial role; infectious disease occurs when the damage caused by pathogens exceeds the host's immune system's response.
Bacteria can be classified into different categories based on their interaction with the host:
- Saprophytes: bacteria that grow in soil and live on dead organic matter.
- Commensal bacteria: harmless microbes that live on the host without causing harm.
- Pathogenic bacteria: capable of causing disease.
- Primary pathogens: cause disease in healthy individuals.
- Opportunistic pathogens: take advantage of preexisting conditions (like weakened immune systems) to cause disease.
Infection routes include: endogenous (self-infection) and exogenous (cross-infection).
- Endogenous infection: commensal bacteria in one part of the body moving to another.
- Exogenous infection: transmission from another source.

Sources of Exogenous Infections

Patients: transmission from patients suffering from an active disease to healthy individuals.
Infected animals: zoonotic infections.
Soil: saprophytic microbes present in soil, vegetation, and similar environments.
Carriers: individuals harboring pathogens without showing clinical symptoms, hence capable of spreading infections to others; classified as convalescent, chronic, or healthy carriers.

Modes of Transmission

Ingestion (food or water).
Inhalation (respiratory tract).
Trauma.
Direct contact (skin-to-skin).
Sexual transmission.
Blood-borne transmission.
Vector-borne transmission.
Vertical transmission (mother-to-child).

Mechanisms of Infection

Exposure: Initial contact with pathogens.
Adhesion: Pathogens attach to host cells.
Invasion: Pathogens enter host cells or tissues.
Colonization: Pathogens multiply and establish themselves.
Toxicity: Release of toxins, directly harming host cells or disrupting their functions. -Tissue damage can manifest as disease.

Microbial Toxins

Microbial products directly harming tissues and altering host metabolism, often causing major symptoms.
- Exotoxins: Secreted toxins with enzymatic activity. They often cause illness (e.g. diphtheria, tetanus, cholera)
- Endotoxins: Components of outer cell wall of Gram-negative bacteria. Released upon cell death, stimulating potent inflammatory reactions.
- Classified by structure and function.

Defense Mechanisms

Innate (non-specific): Immediate responses (e.g., physical barriers, inflammation, phagocytosis, complement system, interferons).
Adaptive (specific): Immune response adapted to particular pathogens (e.g., antibodies, T cells).
Innate responses: immediate responses to infection.
Innate, antigen-nonspecific defenses: local response, including phagocytes (macrophages, neutrophils), natural killer (NK) cells, dendritic cells, interferons, complement system, inflammation/fever, antimicrobial peptides (AMPs).
Non-specific physical and chemical defenses: skin, mucous membranes, stomach acids, lysozyme in tears, expulsion (coughing, sneezing, vomiting, diarrhea).
Adaptive, antigen-specific responses: antibodies and T cells.

Complement System

The complement system is a crucial part of the innate immune system participating in the destruction of pathogens.
Various pathways (classical, alternative, lectin) activate the complement cascade leading to the formation of the membrane attack complex (MAC) and a series of other crucial immune responses.

Phagocytes and Inflammation

Phagocytes (such as macrophages and neutrophils) engulf and destroy pathogens, initiating an inflammatory response.
Inflammation is a localized response following injury or infection, characterized by redness, swelling, heat, and pain; it's a crucial part of the body´s defenses.

Bacterial Pathogenesis

Disease results from tissue damage caused by toxins or direct killing.
Microbes can infect distant tissues.

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Description

Test your knowledge on the immune system and infection transmission with this comprehensive quiz. Explore topics including innate immunity, pathogen defenses, and the roles of specific immune cells. Perfect for students studying immunology or health sciences!