Question 1

Which of the following best describes the role of the skin as a nonspecific defense mechanism?

Accepted Answer

It acts as a physical barrier due to its dry, tightly packed outer layer and high osmotic pressure, making it inhospitable for most pathogens.

Question 2

A patient with a genetic disorder that prevents the production of lysozyme would be most susceptible to which of the following?

Accepted Answer

Infections by Gram-positive bacteria due to reduced breakdown of their cell walls.

Question 3

Which of the following best explains why moderate fever can be beneficial during an infection?

Accepted Answer

It stimulates immune cells to differentiate and grow, and can inhibit the growth of some pathogens by inducing heat shock.

Question 4

Which of the following is a chemical factor that discourages pathogen colonization on the skin?

Accepted Answer

Low pH of sebum secreted on the skin surface.

Question 5

A newborn is unable to produce sufficient transferrin. Which of the following is the most likely consequence?

Accepted Answer

Increased susceptibility to bacterial infections due to more free iron available for microbial growth.

Question 6

Which of the following best describes the function of the ciliary escalator in the respiratory tract?

Accepted Answer

It moves trapped pathogens upward toward the throat to be expelled or swallowed.

Question 7

Which of the following is NOT a mechanical factor in nonspecific host defenses?

Accepted Answer

Low pH of stomach acid.

Question 8

A patient with a compromised normal flora due to prolonged antibiotic use is at increased risk for which of the following?

Accepted Answer

Colonization by opportunistic pathogens due to reduced competition and higher pH.

Question 9

Which of the following best explains the role of complement proteins in the immune response?

Accepted Answer

They bind to antigens, causing a conformational change that activates a cascade leading to inflammation, chemotaxis, opsonization, and cytolysis.

Question 10

Which of the following is a direct effect of activated complement proteins?

Accepted Answer

Cytolysis, which causes cells to lyse.

Question 11

A patient with a defect in vasodilation during inflammation would most likely experience which of the following?

Accepted Answer

Reduced blood flow to injured areas, leading to slower immune cell recruitment.

Question 12

Which of the following best describes the classical pathway of complement activation?

Accepted Answer

It is initiated when antibodies bind to antigens, causing a conformational change that activates complement proteins.

Question 13

Which of the following is an example of a biological nonspecific defense mechanism?

Accepted Answer

Phagocytosis by leukocytes that ingest and destroy pathogens.

Question 14

A patient with a stomach ulcer that raises the pH of their stomach would be at increased risk for which of the following?

Accepted Answer

Infection by ingested pathogens due to reduced antimicrobial activity of stomach acid.

Question 15

Which of the following best explains why vomiting and diarrhea are considered nonspecific defense mechanisms?

Accepted Answer

They rapidly expel pathogens from the gastrointestinal tract before they can colonize.

Question 16

Which of the following is a plausible consequence of decreased salt accumulation on the skin?

Accepted Answer

Increased microbial growth due to reduced osmotic pressure discouraging growth.

Question 17

During inflammation, which of the following events allows immune cells and proteins to access the site of injury?

Accepted Answer

Increased permeability of blood vessels.

Question 18

Which of the following best describes the function of opsonins in the immune response?

Accepted Answer

They coat pathogens to enhance phagocytosis by immune cells.

Question 19

A patient with a deficiency in complement proteins would most likely experience which of the following?

Accepted Answer

Increased susceptibility to infections due to impaired inflammation, chemotaxis, and cytolysis.

Question 20

Which of the following best explains why normal flora help prevent colonization by pathogens?

Accepted Answer

They reduce the pH of skin and vagina and compete for nutrients and space, making it harder for pathogens to establish.

Nonspecific Defenses of the Host ~ Chp 16

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