Deck 23: Human Microbiota and Nonspecific Host Defenses

Question 1

Which of the following innate immunity mechanisms is mismatched with its associated structure or body fluid?

A) lysozyme-tears and saliva
B) mucociliary escalator-intestines
C) highly acidic pH-stomach
D) acidic pH, sebum, fatty acids-skin
E) low pH-urogenital tract

Answer 1

B

Question 2

Which of the following organisms can cause Pseudomembranous enterocolitis?

A) Pseudomonas aeruginosa
B) Clostridium difficile
C) Staphylococcus aureus
D) Escherichia coli
E) Streptococcus pyogenes

Answer 2

B

Question 3

Which of the following types of cells are antigen presenters in humans?

A) only T helper cells
B) B lymphocytes and macrophages
C) only macrophages
D) only dendritic cells
E) macrophages and dendritic cells

Answer 3

E

Question 4

The mucociliary escalator functions to:

A) trap and sweep pathogens into the urine
B) kill via lysozyme activity
C) harbor normal flora that discourage pathogens from colonizing
D) produce fatty acids with a low pH that kills microbes
E) trap and sweep microbes from the bronchi back up to the throat to be swallowed

Question 5

Which of the following is NOT an integral part of the inflammatory process?

A) dilation of blood vessels
B) release of histamines and prostaglandins
C) chemotaxis of polymorphonuclear leukocytes
D) extravasation
E) antibody synthesis

Question 6

The aerobe to anaerobe ratio showing the greatest difference in concentrations occurs in the:

A) intestinal tract
B) mouth
C) skin
D) respiratory tract
E) genitourinary tract

Question 7

Which of the following is NOT a lymphoid organ?

A) tonsils and adenoids
B) spleen
C) appendix
D) stomach
E) bone marrow

Question 8

Neisseria species:

A) are never found as normal microbial flora of humans
B) cause serious diarrhea
C) are used as probionts
D) are obligate intracellular parasites
E) are Gram-positive cocci

Question 9

Which of the following are the major phagocytic cells in the body?

A) T and B lymphocytes
B) basophils and eosinophils
C) erythrocytes
D) neutrophils and macrophages
E) epithelial cells with cilia

Question 10

Which of the following is rarely normal flora of the urethra?

A) Staphylococcus aureus
B) Bacteroides spp.
C) Mycobacterium spp.
D) Escherichia coli
E) Peptostreptococcus spp.

Question 11

Microbial colonization of the eye is inhibited by the presence of antimicrobial factors, like:

A) interferons
B) complement
C) mucous
D) defensins
E) lysozyme

Question 12

Which of the following is NOT found in the epidermis layer?

A) hair follicle
B) sebaceous gland
C) blood vessels
D) sweat glands
E) all of the above

Question 13

An organism found on human skin that derives benefit from the host but does NOT harm it is described as a/an:

A) parasite
B) commensal
C) opportunist
D) pathogen
E) mutualist

Question 14

All of the following statements are correct about microbial colonization of the human body EXCEPT:

A) The skin is a highly selective niche for certain microbes.
B) Oral microbiota can cause endocardiatis after dental surgery.
C) Cardiovascular normal flora are commensal species.
D) There are 1,000 times more anaerobes in the colon than aerobes.
E) Intestinal bacteria help modulate human mucosal immunity.

Question 15

Which of the following is NOT a symptom of periodontal disease?

A) red, swollen gums
B) swollen tongue
C) bleeding gums
D) gum shrinkage
E) teeth drifting apart

Question 16

Which part of the genitourinary tract maintains a normal flora population?

A) kidney
B) ureters
C) bladder
D) urethra
E) distal urethra

Question 17

Which of the following should be free from microbes in a healthy individual?

A) nose
B) mouth
C) skin
D) cerebrospinal fluid
E) genitourinary tract

Question 18

Which of the following organisms are commonly used as probiotics?

A) Streptococcus mutans and Lactobacillus acidophilus
B) Bacteroides and Lactobacillus acidophilus
C) Enterococcus and Enterobacter species
D) Bifidobacterium and Lactobacillus acidophilus
E) Diphtheroids and Fusobacterium species

Question 19

Which of the following is correct regarding inflammation?

A) The cardinal signs include rash.
B) Some of the phagocytes are stimulated to secrete antibodies specific for the invading pathogen.
C) The response is the same for viruses, bacteria, and injury to the body.
D) Differentiation of B cells into plasma cells occurs at the site of infection.
E) AIDS patients have little or no inflammatory response when they infected.

Question 20

Which of the following is a primary lymphoid organ?

A) adenoids
B) appendix
C) Peyer's patches
D) thymus
E) tonsils

Question 21

A man has been taking excessive amounts of antacids for heartburn. These tablets are very alkaline. Which defense mechanism might be altered by his actions?

A) mucociliary escalator
B) lysozyme
C) pH of stomach
D) flushing action of urine
E) skin pH

Question 22

Which of the following can interfere with adherence of phagocytic cells to the pathogen?

A) M protein on cell walls of Streptococcus pyogenes
B) lipid produced by Mycobacterium tuberculosis
C) leukocidin released by staphylococci
D) lipopolysaccharide of Gram-negative bacteria
E) ability of Rickettsia rickettsii to prevent release of lysosomal enzymes

Question 23

What is the correct order of the events in phagocytosis? (1) discharge of waste material, (2) fusion of the phagosome with a lysosome, (3) adherence of the microbe to phagocytes, (4) digestion of ingested microbe, (5) formation of a phagosome, (6) ingestion of microbe by phagocyte

A) 3, 6, 5, 2, 4, 1
B) 3, 4, 6, 5, 2, 1
C) 6, 5, 2, 4, 3, 1
D) 5, 2, 3. 6, 4, 1
E) none of the above

Question 24

Interleuken-1 and IL-6 were detected in the serum. This indicates:

A) mucosal IgA has been degraded
B) B lymphocyte activation
C) a macrophage has encountered an antigen
D) cancer cells are forming
E) natural killer cells have autolyzed

Question 25

Opsonization is a process whereby the innate and adaptive immune mechanisms work together:

A) to phagocytize an invader
B) to activate complement proteins
C) for antibody secretion
D) to destroy cancer cells
E) during apoptosis

Question 26

All of the following statements are correct regarding defensins EXCEPT:

A) They are produced by skin, GIT, and lung cells for defense when stimulated.
B) They form channels in bacterial cytoplasmic membranes, ultimately killing the cell.
C) The transmembrane electrical potential allows defensins to penetrate and kill cells.
D) Like antibodies, they are highly specific in pathogen neutralization.
E) Variation in defensins produced by different animals partially explains varying susceptibility of hosts to pathogens.

Question 27

Polymixin B is a small cationic peptide antibiotic that mimics the action of:

A) macrophages
B) lysosomes
C) defensins
D) killer cells
E) antibodies

Question 28

A woman falls and suffers a 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?

A) mucociliary escalator
B) normal skin flora
C) acidic skin secretions
D) lysozyme
E) phagocytosis and the inflammatory response

Question 29

How does IFN-gamma protect the host?

A) It induces dsRNA endonucleases.
B) It interferes directly with viral replication.
C) It has an immunomodulatory role.
D) It induces fever at the hypothalamus.
E) It blocks adhesion of pathogens.

Question 30

A bacterium can live inside a phagocyte by preventing:

A) complement activation
B) interferon production
C) defensin production
D) fusion of the phagosome with a lysosome
E) inflammation

Question 31

Which of the following pairs is mismatched?

A) extravasation-movement of leukocytes through endothelial cells into tissues
B) pus-tissue debris and dead phagocytes in a white or yellow fluid
C) chemotaxis-chemical degradation inside a phagolysosome
D) autophagy-destruction of intraphagocytic pathogen
E) scab-dried blood clot over injured tissue

Question 32

Extravasation is the process by which __________ moves from the bloodstream into surrounding tissues.

A) neutrophils
B) natural killer cells
C) antibodies
D) interferons
E) complement

Question 33

In cystic fibrosis, a mutation has rendered the receptor for binding and inactivating Pseudomonas defective. The affected gene is the CFTR. Where is the CFTR gene product located?

A) cytosol
B) nucleus
C) plasma membrane surface
D) mitochondria
E) phagosome

Question 34

Defensins are short cationic peptides that:

A) are produced by skin, GIT, and lung cells for defense when stimulated
B) bind to specific receptors to gain entry into cells
C) are only produced by phagocytes upon activation
D) inhibit microbial DNA synthesis
E) are equally effective at killing eukaryotic and prokaryotic

Question 35

A cascade of which of the following enzymes, when activated, causes the macrophage to commit suicide in a programmed response called apoptosis?

A) caspases
B) ligases
C) kinases
D) phosphorylases
E) proteases

Question 36

Lysozyme and the antibiotic penicillin have similar mechanisms of action in that they both cause damage to the bacterial:

A) cell membrane
B) capsule
C) cell wall
D) DNA
E) ribosomes

Question 37

Which of the following is NOT associated with the oxidative burst employed by phagocytic cells to kill bacteria?

A) hydrogen peroxide
B) oxygen radicals
C) NADPH oxidase
D) catalase
E) nitric oxide

Question 38

Interferons:

A) are antibacterial agents produced by skin, GIT, and lung cells
B) are secreted by eukaryotic cells in response to intracellular infection
C) only produced by activated phagocytes
D) are host-specific and virus-specific
E) can block virus replication

Question 39

Cystic fibrosis patients are __________ prone to infection by mucoid strains of Pseudomonas aeruginosa as compared with the rest of the population.

A) less
B) more
C) equally
D) not at all
E) none of the above

Question 40

Which of the following is a process normally used by the host to kill unwanted host cells?

A) invagination
B) secretion
C) osmotic lysis
D) apoptosis
E) efflux

Question 41

Increased levels of C-reactive protein in the blood have been linked to increased risk of which of the following?

A) kidney disease
B) liver disease
C) cardiovascular disease
D) diabetes
E) Crohn's disease

Question 42

How does the membrane attack complex (MAC) kill Gram-negative bacteria?

A) through opsonization
B) it dissolves the lipid membrane
C) it creates a pore on membrane through which cellular content leaks out, killing the cell
D) it creates a pore on membrane through which lysozyme in body fluid enters, to cleave peptidoglycan
E) it creates a pore on membrane through which sodium and water enter the cell to cause osmotic lyses

Question 43

What causes subacute bacterial endocarditis?

Question 44

Briefly explain the microbiology of dental plaque formation.

Question 45

Increased levels of C-reactive protein in the blood have been linked to increased risk of which of the following?

A) kidney disease
B) liver disease
C) cardiovascular disease
D) diabetes
E) Crohn's disease

Question 46

What factors might explain the prevalence of Gram-positive bacteria on the human skin epidermal layer?

Question 47

Explain how differences in gut microbiota can account for obesity and leanness in humans.

Question 48

Which the following creates a channel in target cell membranes?

A) complement
B) defensins
C) natural killer cells
D) A and B
E) all of the above

Question 49

Toll-like receptors are eukaryotic membrane proteins that bind with bacterial surface molecules and:

A) form channels through which bacterial proteins can enter the eukaryotic cell
B) cause the cell to phagocytize the bacteria
C) release antibiotics to kill the bacteria
D) release chemicals that trigger host defenses against the bacteria
E) activate the complement cascade

Question 50

Which of the following is an example of a semispecific, innate immune mechanisms associated with mucosal surfaces?

A) secretory IgA prevents adhesion to mucosal surface
B) extravasation of neutrophils is triggered by specific signals
C) interferons produced by host will act on specific viruses in the mucosa
D) Toll-like receptors on host bind specific pathogen-associated molecular pattern (PAMP)
E) type of inflammation mounted varies with pathogen

Question 51

Why is acne treated with antibiotics? Describe the process of acne formation.

Question 52

Natural killer cells target:

A) infected cells that have lost MHC class I
B) bacterial cells that have lost MHC class I
C) bacterial cells that are coated with complement
D) infected cells that have lost C-reactive protein
E) infected cells that secrete cytokines

Question 53

Why is it important for people with mitral valve prolapse (MVP) to take antibiotics prior to a dental exam or procedure?

Question 54

Discuss how Propionibacterium acnes-an anaerobic Gram-positive normal flora of the skin causes acne.

Question 55

Which of the following, produced by natural killer cells, punctures the membrane of target cells, causing them to burst?

A) perforins
B) trypsins
C) magainins
D) lysins
E) defensins

Question 56

How can an anaerobic microbe grow on the skin or on body parts that are constantly exposed to air?

Question 57

Detection of high levels of mannose-binding lectin in the blood could signify:

A) the presence of an invading pathogen
B) virus replication is ongoing
C) B cells are about to be activated in plasma cells
D) high levels of interferons
E) differentiation of leukocytes is in progress

Question 58

How does Heliobacter pylori defy stomach acidity?

Question 59

Which of the following nonspecific defense mechanisms is already present and available to respond immediately to infection (and does NOT need to be synthesized)?

A) interferon
B) selectin
C) complement
D) nitric oxide
E) prostaglandins

Question 60

Microbes on humans sharpen our immunity and protect from infection, but these benefits come with considerable risk. Explain.

Question 61

Explain why healthy individuals are usually "immune" to cholera, whereas malnourished individuals are not.

Question 62

Describe distinguishing characteristics of innate and adaptive immunity.

Question 63

Is it correct to state that bacteria introduced through a skin cut will most likely be engulfed by Langerhans cells?

Question 64

Are the Langerhans cells of the skin-associated lymphoid tissue (SALT) related to the islets of Langerhans of the pancreas that secrete insulin? What is their function?

Question 65

Describe two ways by which bacteria resist or evade killing by phagocytosis.

Question 66

Why would complement NOT be considered a part of adaptive immunity?

Question 67

How is it that Gram-positive cells are more resistant to complement than Gram-negative cells?

Question 68

How is it that Clostridium difficile, often a part of the normal intestinal microflora, can be the causative agent of pseudomembranous enterocolitis?

Question 69

Describe how the small polypeptide bradykinin promotes edema and pain.

Question 70

Describe opsonization, the process in which innate and adaptive immunity work together to engulf an invader.