Question 1

A differential cell count is used to determine each of the following EXCEPT

Accepted Answer

A differential cell count is only used to determine the numbers and percentages of different types of white blood cells present in a sample. It does not provide any information about red blood cell count or any conditions like leukocytosis or leukopenia.

Question 2

All of the following protect the skin and mucous membranes from infection EXCEPT

Accepted Answer

HCl is a component of gastric acid in the stomach, which is involved in the digestion of food and not a part of the skin or mucous membrane barrier. All other options listed aid in protecting the skin and mucous membranes from infection.

Question 3

Which of the following is found normally in serum?

Accepted Answer

Complement proteins are found normally in serum as part of the immune defense system. They can activate a cascade of reactions leading to destruction of invading microorganisms. Interferon, histamine, leukocytosis-promoting factor, and TLRs are not typically found in serum.

Question 4

The complement protein cascade is the same for the classical pathway,alternative pathway,and lectin pathway after the point in the cascade where the activation of ________ takes place.

Accepted Answer

After C3 is activated, the complement protein cascade converges and proceeds through the same steps for all three pathways. This includes the formation of the membrane attack complex (MAC), which leads to cell lysis. The activation of C1 is specific to the classical pathway, while C2, C5, and C6 are activated in both the classical and alternative pathways.

Question 5

Each of the following is an effect of complement activation EXCEPT

Accepted Answer

Complement activation can interfere with viral replication by directly killing infected cells, but it is not a direct effect of complement activation. The other options (B, C, D, and E) are all direct effects of complement activation.

Question 6

Which of the following exhibits the highest phagocytic activity?

Accepted Answer

Macrophages exhibit the highest phagocytic activity compared to the other cell types listed. They are specialized phagocytic cells that are important for engulfing and destroying invading pathogens and cellular debris. Neutrophils also exhibit high phagocytic activity, but not as high as macrophages. Eosinophils, basophils, and erythrocytes are not phagocytic cells and do not possess significant phagocytic activity.

Question 7

All of the following increase blood vessel permeability EXCEPT

Accepted Answer

Lysozymes are enzymes involved in the breakdown of bacterial cell walls and do not have a role in increasing blood vessel permeability. Kinins, prostaglandins, histamine, and leukotrienes all increase blood vessel permeability.

Question 8

The function of the "ciliary escalator" is to

Accepted Answer

The ciliary escalator is a mechanism in the respiratory system that traps inhaled dust and microorganisms in mucus and propels it away from the lower respiratory tract towards the throat, where it can be swallowed or expelled. This helps to keep the lower respiratory tract clear of pathogens and debris.

Question 9

Normal microbiota provide protection from infection in each of the following ways EXCEPT

Accepted Answer

Normal microbiota do not produce lysozyme. Lysozyme is an enzyme that breaks down bacterial cell walls and is produced by a variety of cells including white blood cells, tears, and breast milk. The other choices are all ways in which normal microbiota provide protection from infection.

Question 10

Which of the following statements is TRUE?

Accepted Answer

Gamma interferon causes bactericidal activity by macrophages. Alpha interferon promotes antiviral defense mechanisms while beta interferon stimulates the production of antiviral proteins. Therefore, options A, D, and E are incorrect.

Question 11

The antimicrobial effects of AMPs include all of the following EXCEPT

Accepted Answer

AMPs enhance phagocytosis and do not inhibit it. Therefore, option E is the correct answer.

Question 12

Margination refers to

Accepted Answer

Margination refers to the adherence of phagocytes to the lining of blood vessels. This is a critical step in the process of phagocyte recruitment to sites of infection or injury.

Question 13

Phagocytes utilize all of the following to optimize interaction with (getting to and getting hold of)microorganisms EXCEPT

Accepted Answer

Lysozyme is an enzyme that breaks down peptidoglycan in bacterial cell walls and is not directly involved in optimizing phagocyte interactions with microorganisms. A, B, C, and E are all mechanisms used by phagocytes to interact with microorganisms.

Question 14

Each of the following provides protection from phagocytic digestion EXCEPT

Accepted Answer

Formation of phagolysosomes is a process in which phagosomes, containing engulfed pathogens, fuse with lysosomes to form phagolysosomes. This process leads to the degradation of the pathogens. Therefore, the formation of phagolysosomes does not provide protection from phagocytic digestion. All other options (M protein, capsules, leukocidins, and biofilms) can provide protection from phagocytic digestion by preventing or hindering phagocytosis.

Question 15

The swelling associated with inflammation decreases when the fluid

Accepted Answer

The swelling associated with inflammation decreases when the fluid goes into lymph capillaries. Lymphatic vessels are responsible for draining excess fluid from tissues and returning it to the bloodstream. Inflammatory fluid is drained into lymphatic vessels, reducing swelling and inflammation.

Question 16

TLRs attach to all of the following EXCEPT

Accepted Answer

TLRs (Toll-like receptors) attach to flagellin, LPS, PAMPs, and peptidoglycan, but not to AMPs (antimicrobial peptides).

Question 17

A child falls and suffers a deep cut on her leg.The cut went through her skin and she is bleeding.Which of the following defense mechanisms will participate in eliminating contaminating microbes?

Accepted Answer

When a cut or wound occurs and causes bleeding, the body's first line of defense is inflammation. Inflammatory mediators are released that cause blood vessels to dilate, leading to increased blood flow and the recruitment of immune cells, including phagocytes. Phagocytes, such as macrophages, are capable of engulfing and destroying invading microbes to prevent infection. Therefore, phagocytosis in the inflammatory response would participate in eliminating contaminating microbes. The other choices are also defenses against pathogens, but they are not directly involved in the elimination of microbes in a wound.

Question 18

Which of the following statements about fixed macrophages is FALSE?

Accepted Answer

Fixed macrophages develop from monocytes, not neutrophils.

Question 19

Which of the following is an effect of opsonization?

Accepted Answer

Opsonization is the process by which bacteria or other microorganisms are marked for destruction by immune cells such as phagocytes. Opsonins (such as antibodies or complement proteins) bind to the surface of the microorganisms, making them more attractive to phagocytes. This increased attraction results in increased adherence of phagocytes to the microorganisms, which is the effect described in choice A.

Question 20

Innate immunity

Accepted Answer

Innate immunity is the first line of defense against pathogens and is present at birth. It is nonspecific, meaning that it can respond to a wide range of pathogens, but does not have a memory component.

Answer A is incorrect because innate immunity is actually faster than adaptive immunity in responding to pathogens.

Answer C is incorrect because only adaptive immunity involves a memory component.

Answer D is incorrect because T cells and B cells are part of adaptive immunity, not innate immunity.

Answer E is incorrect because innate immunity provides a baseline level of protection against pathogens, and actually reduces susceptibility to disease.

Quiz 16: Innate Immunity: Nonspecific Defenses of the Host