Question 1

Which of the following best describes the difference between the first and second lines of host defense?

Accepted Answer

The first line of defense involves physical and chemical barriers, while the second line involves cellular and chemical responses such as inflammation and phagocytosis.

Question 2

Which of the following is an example of a physical barrier in the first line of defense?

Accepted Answer

The ciliated epithelium of the respiratory tract

Question 3

What is the primary function of pattern recognition receptors (PRRs) on phagocytes?

Accepted Answer

To recognize and bind to pathogen-associated molecular patterns (PAMPs) on microbes

Question 4

Which of the following blood cells is most likely to increase in number during a bacterial infection and is a primary component of pus?

Accepted Answer

Neutrophils

Question 5

A patient presents with redness, heat, swelling, and pain at the site of a cut. Which process is primarily responsible for these symptoms?

Accepted Answer

Inflammatory response

Question 6

Which of the following is a benefit of fever during infection?

Accepted Answer

It inhibits the multiplication of temperature-sensitive microorganisms.

Question 7

Which of the following best describes the role of interferons in host defense?

Accepted Answer

They bind to cell surfaces and induce the production of proteins that inhibit viral replication.

Question 8

Which of the following is the correct sequence of events in phagocytosis?

Accepted Answer

Chemotaxis → Ingestion → Phagolysosome formation → Destruction → Excretion

Question 9

Which of the following statements about the complement system is TRUE?

Accepted Answer

The classical pathway is initiated by the binding of complement proteins to antibodies attached to microbes.

Question 10

A patient with a genetic defect in the formation of the membrane attack complex (MAC) would have increased susceptibility to which of the following?

Accepted Answer

Bacterial infections due to inability to lyse pathogen membranes

Question 11

Which of the following is a function of cytokines in the immune response?

Accepted Answer

They regulate, stimulate, or suppress immune cell activity.

Question 12

Which of the following is an example of a chemical barrier in the first line of defense?

Accepted Answer

Lysozyme in tears and saliva

Question 13

Which of the following best explains why the human microbiome is considered a part of the first line of defense?

Accepted Answer

It competes with pathogens for nutrients and alters local pH, making it harder for pathogens to colonize.

Question 14

Which of the following is a correct statement about diapedesis?

Accepted Answer

It is the process by which white blood cells migrate out of blood vessels into tissues.

Question 15

A patient is found to have a deficiency in neutrophil function. Which of the following would most likely be impaired?

Accepted Answer

Ability to phagocytose and destroy bacteria during acute inflammation

Question 16

Which of the following is a pro-inflammatory cytokine?

Accepted Answer

Interleukin-1 (IL-1)

Question 17

Which of the following is a correct description of the role of antimicrobial peptides in innate immunity?

Accepted Answer

They are short proteins that can insert into bacterial membranes and cause cell lysis.

Question 18

Which of the following best describes the function of the lymphatic system in immunity?

Accepted Answer

It provides a route for the return of extracellular fluid to the circulatory system and acts as a site for immune cell activation.

Question 19

Which of the following is a distinguishing feature of the third line of defense compared to the first and second lines?

Accepted Answer

It provides long-term, specific immunity through the action of lymphocytes.

Question 20

Which of the following best explains why chronic inflammation can be harmful to the body?

Accepted Answer

It can result in tissue injury, destruction, and contribute to diseases such as cardiovascular disease.

Host Defenses and Innate Immunity: An Overview

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