Exam 3 Flashcards
Endotoxins are also known as
Lipid A.
When would endotoxins be released from a bacterial cell?
When the cell dies
Which of the following would be the first sign of an infection that resulted in the release of endotoxin?
Fever
Why is a release of endotoxin into the bloodstream potentially deadly?
It can lower blood pressure and cause the patient to go into shock.
An exotoxin that has the ability to kill or damage host cells is referred to as a(n)
cytotoxin.
Which domain of the A-B toxin binds to cell surface receptors on the host cell?
B domain
How are superantigens different from other types of exotoxins?
Superantigens cause an overstimulation of the host immune system.
A person who attended a picnic early in the day develops a very high fever and is unresponsive by the evening. This person most likely has been exposed to a(n)
superantigen
A patient who has been hospitalized with uncontrolled muscle spasms has probably been infected with bacteria that secrete a(n)
neurotoxin
In mice, the LD50 for staphylococcal enterotoxin is 1350 ng/kg, and the LD50 for Shiga toxin is 250 ng/kg. Which of the following statements is true?
Shiga toxin is more lethal than staphylococcal enterotoxin.
Which of the following would be an example of an infection initiated via the parenteral route?
An individual contracts hepatitis B from an accidental stick with a contaminated needle.
Which of the following statements about adherence is true?
Most bacterial adhesins are glycoproteins or lipoproteins.
Which disease would be potentially propagated in an environment without functional plumbing and in which drinking water is contaminated with sewage?
cholera
Which type of bacterial enzyme helps spread Streptococcus pyogenes by digesting blood clots?
fibrinolysin
Which of the following features of Salmonella prevent it from being phagocytosed?
Flagella
Where do Salmonella pathogens grow and replicate in the infected host?
Inside phagocytes
Where is the site of Shigella attachment in the host?
M cells
How do Shigella cells move between host cells?
They can polymerize actin molecules from the epithelial cells into tail-like structures that propel them from one cell to another.
What is the etiologic agent of typhoid?
Salmonella
How are immune cells able to detect foreign pathogens?
They are able to detect structures on the surfaces of foreign cells that are not found in the host.
How does a capsule help certain bacteria evade detection by the immune system?
The capsule is composed of polysaccharides that are similar to those found in the host; thus, the immune system does not recognize it as foreign.
Which of the following microorganisms actually grows inside the macrophage?
Tuberculosis bacterium
How does the protozoan Trypanosoma evade detection by the immune system?
It can change the surface antigens frequently, preventing the immune system from tracking it.
Certain traits that allow pathogens to create infection and cause disease are termed
virulence factors.
Which of the following enzymes breaks down the “glue” that holds cells together?
Hyaluronidase
Which of the following virulence factors would be found in Staphylococcus aureus?
Staphylokinase
How do fibrinolysins enhance a pathogen’s virulence?
They break down fibrin proteins that are involved in clot formation, allowing the cells to penetrate deep into damaged skin.
What are leukocidins?
Molecules that are capable of destroying phagocytes
Measles viruses are capable of inactivating host defenses by
suppressing the immune system.
Meningitis and gonorrhea are caused by
Neisseria species.
How do superantigens enable pathogens to hide from the immune system if they actually stimulate the immune system?
They cause the immune system to produce an exaggerated response, distracting it from the actual pathogen.
How can capsules enable bacteria to evade the immune system?
Capsules block the complement biding sites on the surface of the pathogen.
Which statement regarding endotoxins is true?
One consequence of endotoxins is the activation of blood-clotting proteins
In which of the following cases would the Limulus amebocyte lysate (LAL) assay be used?
to ensure that a sterilized medical device is free of endotoxin
Which of the following toxins and descriptions do NOT match?
Vibrio enterotoxin: a superantigen that destroys epithelial cells
Which of the following statements about lysogenic conversion is true?
Exotoxin production by bacteria is frequently the result of a lysogenic infection.
What do hyaluronidase and kinase have in common?
They are both enzymes involved in evading host defense.
According to your Concept Map, which of the following organisms exhibits antigenic variation?
N. gonorrheae
Which of the following virulence factors could directly prevent phagocytosis and/or phagocytic degradation?
waxy lipids
M proteins
capsules
Which of the following is NOT a cytopathic effect (CPE) of viruses?
chromosomal changes in the host cell
the formation of a syncytium
formation of inclusion bodies
All of the listed choices are possible cytopathic effects of viruses.
Julie is preparing vegetables for dinner and accidentally cuts her finger. She washes it with soap and water before covering it with a bandage. A short while later, Julie notices that her finger is red, swollen, warm to the touch, and very painful. Which of the following describes the process going on in Julie’s finger?
inflammation
Inflammation is part of the second line of defense that is activated when the first line of defense is breached. Julie’s first-line defenses were damaged when her injury occurred. Which of the following represents the first line of defense?
skin and mucous membranes
As mentioned previously, the second line of defense is activated when the first line of defense fails. In Part A, you identified one of these defenses as inflammation, which occurs when the body responds to a foreign antigen and increases fluid accumulation in a specific area. An added benefit of this excess fluid is that it also brings immune cells to the area to aid clearance of foreign antigens. In Julie’s situation, that added fluid would bring immune cells to prevent any microbial infections that could be caused if microbes were introduced when she cut her finger. Which of the following cell types is NOT part of the second line of defense?
plasma cells
The adaptive immune response, or third line of defense, is activated when the first and second lines of defense do not succeed in containing an infection. It is adaptive because the cells in this part of the immune system are capable of responding to specific pathogens. Another important feature of the third line is the ability of these cells to create memory cells. Why are memory cells an important product of an immune response?
Memory cells allow subsequent immune responses against the same antigen to occur more strongly and more quickly.
Which non-specific defense mechanism is mismatched with its associated body structure or body fluid?
mucociliary escalator intestines
Which group contains ONLY innate physical defenses?
intact skin, tears, ciliary escalator
What direct effect do histamines and leukotrienes have on capillaries?
They allow capillary walls to open and become leaky.
Diapedesis is
the migration of phagocytes through blood vessels to the site of tissue damage.
Why is vasodilation important to tissue repair?
It allows for an increased delivery of oxygen, nutrients, and phagocytes to the site of damage.
Pus is comprised of
dead phagocytes.
Which of the following can release histamines?
Cells from damaged tissues and the complement pathway
All of the following pertain to fever EXCEPT that it
accelerates microbial growth by increasing iron absorption from the digestive tract.
The antimicrobial effects of AMPs include all of the following EXCEPT
inhibition of phagocytosis.
Which of the following statements about innate immunity is true?
Innate immunity is present at birth.
Mucous membranes are a part of
innate defense.
According to the animation, B cells interact directly with
helper T cells.
Which of the following defense systems would be involved in eliminating virally-infected cells?
T lymphocytes
According to the animation, antibodies interact with which innate defenses?
Phagocytosis and the complement system
Which cells directly attack abnormal cells in the body?
Cytotoxic T cells
If one is examining a blood smear from a patient with a parasitic worm infection, which of the following leukocytes would be found in increased numbers?
eosinophils
A response that is uniquely directed against pathogenic Bordetella pertussis would involve what component?
Antibodies
First line defenses have what aspect in common with each other?
They are physical barriers against invading pathogens.