4th exam part 4

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Questions and Answers

What is the primary function of B-cells in the humoral immune response?

Cytotoxic T-cell activation

Memory cell formation

Antibody production to extracellular pathogens (correct)

Migration to infection sites

What defines a true pathogen?

Normal flora that occasionally lead to infections

Microbes that only cause disease in immunocompromised individuals

Pathogens that are commonly found in the environment

Organisms that can cause disease in otherwise healthy people (correct)

What does the term virulence refer to in infectious disease?

The quantitative ability of a pathogen to cause disease (correct)

The ability of the host to defend against pathogens

The genetic makeup of the pathogen

The symptoms produced by the disease

Which of the following describes opportunistic pathogens?

Microbes that infect only after the body’s defenses are compromised Signup and view all the answers

Which type of infection is characterized by beneficial microbes living within the host?

Normal flora Signup and view all the answers

What is meant by the term infectious dose?

The number of pathogens required to establish an infection Signup and view all the answers

Which of the following is NOT considered a virulence factor?

Host immune response Signup and view all the answers

Which of the following statements accurately describes pathogenicity?

Pathogenicity can vary from one organism to another Signup and view all the answers

What characteristic is associated with communicable diseases?

They can spread easily between individuals Signup and view all the answers

Which aspect of the immune response is associated with cellular immunity?

Cytotoxic T-cell activation Signup and view all the answers

What does ID50 represent in microbiological studies?

Infectious dose for 50% of the test population Signup and view all the answers

Which of the following factors determines virulence in pathogens?

Combination of various factors Signup and view all the answers

What is the LD50 value associated with?

Toxicity level that kills 50% of a population Signup and view all the answers

Which of these is considered an exoenzyme?

Lipase Signup and view all the answers

What is the role of adhesins in bacterial pathogenesis?

To bind to host cell receptors Signup and view all the answers

Which type of toxin is characterized by being released only after the bacterial cell dies?

Endotoxin Signup and view all the answers

Which of the following statements about exotoxins is true?

They are typically proteins and highly toxic. Signup and view all the answers

What type of bacteria primarily release endotoxins?

Gram-negative bacteria Signup and view all the answers

Which of the following best describes toxemia?

The presence of toxins in the host's blood Signup and view all the answers

What is the primary metabolic product of exotoxins?

Proteins Signup and view all the answers

What is the role of immune memory in the humoral immune response?

To enhance the rapid response to previously encountered pathogens Signup and view all the answers

Which of the following best defines a primary pathogen?

An organism that can cause disease in healthy individuals Signup and view all the answers

How does virulence differ from pathogenicity?

Virulence quantifies the severity of disease caused by a pathogen Signup and view all the answers

What characteristic distinguishes opportunistic pathogens from true pathogens?

Opportunistic pathogens are always part of normal flora Signup and view all the answers

Which of the following statements accurately describes infectious dose?

It is the number of organisms needed to establish an infection Signup and view all the answers

Which of the following factors is not a virulence factor?

The ability to replicate rapidly Signup and view all the answers

What is the primary implication of a disease being termed communicable?

It can be transmitted from one host to another Signup and view all the answers

Which of the following describes virulence factors?

Biotic factors that can increase the severity of disease Signup and view all the answers

What aspect of infectious disease does 'ease of spread' relate to?

The infectious dose required to establish an infection Signup and view all the answers

What does a smaller LD50 value indicate about a toxin?

The toxin has a higher potency. Signup and view all the answers

Which of the following contributes to the ability of bacteria to adhere to host cells?

Adhesins Signup and view all the answers

What is the role of exoenzymes in bacterial pathogenicity?

They enhance the invasiveness of bacteria. Signup and view all the answers

Which of the following statements is true regarding endotoxins?

Endotoxins are released only upon bacterial cell death. Signup and view all the answers

Which of the following is a characteristic feature of exotoxins?

They are secreted by living bacteria. Signup and view all the answers

What does toxigenicity refer to in terms of microbial pathogenicity?

The ability to produce a toxin. Signup and view all the answers

Which bacterium has the lowest ID50 via skin entry according to the information?

Bacillus anthracis Signup and view all the answers

Which of the following factors contributes to the virulence of an organism?

A combination of various factors Signup and view all the answers

What is the primary component of the cell wall of Gram-negative bacteria associated with endotoxins?

Lipopolysaccharide Signup and view all the answers

Which term describes the presence of a toxin in the host's blood?

Toxemia Signup and view all the answers

Study Notes

Infectious Disease

Ants do not get sick because they have "little anty bodies". This is a joke.
Innate immunity is the first line of defense against pathogens.
Adaptive immunity is a more complex response, involving T cells and B cells.
B-cell activation, antibody production against extracellular pathogens, and immune memory are parts of the humoral response.
Cellular response includes cytotoxic T-cell activation, migration, and immune memory.
Antibodies bind to antigens to neutralize, agglutinate or precipitate them. This inactivates antigens and enhances phagocytosis.
Natural immunity is acquired through normal life experiences.
Active immunity occurs when a person's immune system develops its own response to a microbe.
Passive immunity occurs when one person receives preformed immunity made by another person.
Artificial immunity is purposefully acquired through medical procedures (also called immunization).
Host-microbe interactions involve colonization of the host with microorganisms. Infection does not always lead to noticeable adverse effects. Communicable diseases spread from host to host.
Beneficial microbes are a part of normal flora living in and on the body, like those found in the gut (500 to 1000 different species).
Harmful microbes are pathogenic microbes that cause disease when the body's defenses are down, also called opportunistic pathogens.
Pathogenicity is the ability to cause disease which can be possessed by true pathogens or opportunistic pathogens.
Virulence factors include capsules and cell wall components that help bacteria penetrate or evade host defenses, enzymes, siderophores, and antigenic variation.
Damage to host cells, direct damage, toxins (exotoxins and endotoxins), and lysogenic conversion are also considered virulence factors.
Virulence is a quantitative term referring to a pathogen's disease-causing ability.
Highly virulent organisms have a high degree of pathogenicity and are more likely to cause disease.
Biotic factors that lead to increased virulence include morphological characteristics, metabolic pathways, toxins, and enzymes.
Infectious dose is the number of organisms required to establish infection. Diseases with a small infectious dose spread more easily than those requiring large numbers.
ID₅₀ is the infectious dose for 50% of the test population.
LD₅₀ is the lethal dose (of a toxin) for 50% of the test population.
Smaller LD or ID means a more toxic or virulent organism.
Portal of entry includes mucous membranes, respiratory tract, gastrointestinal tract, genitourinary tract, conjunctiva, skin, and parenteral route. Infection can occur in several ways in the same way that pathogens leave the body.
Adherence factors involve binding by adhesions/ligands to receptors on host cells (glyco- or lipoproteins). Those include glycocalyx, fimbriae, and M protein.
Exoenzymes/Proteins are enzymes or proteins secreted by bacteria, used for penetration and degradation of host defense proteins (Antibodies, complement, Cytokines).
Toxins are substances that contribute to pathogenicity. Toxigenicity is the ability to produce a toxin. Toxemia is the presence of toxin in the host's blood. Toxoid is an inactivated toxin used in a vaccine. Antitoxin is antibodies against a specific toxin.
Endotoxins are found in cell walls or cells, released after death. Exotoxins are secreted by the organism and are highly toxic.
Metabolic pathways are degradation of antibiotics (beta-lactamases), export pumps for antimicrobials, and glycogen degradation.

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Description

Explore the key concepts of infectious disease, including types of immunity such as innate, adaptive, active, passive, and artificial. Understand the roles of antibodies, T cells, and B cells in the immune response. This quiz will test your knowledge on host-microbe interactions and immune mechanisms.