Nokea
Which compounds produced by microorganisms can cause fever in humans and can withstand autoclaving?
- A. endotoxin
- B. Lipid A
- C. lipopolysaccharide
- D. peptidoglycan
Correct Answer: D
Rationale: The correct answer is D, peptidoglycan. Peptidoglycan is a component of bacterial cell walls that can trigger fever in humans. It is a sturdy molecule that can withstand autoclaving.
A: Endotoxin is a component of the outer membrane of Gram-negative bacteria, not resistant to autoclaving.
B: Lipid A is the toxic component of endotoxin, not resistant to autoclaving.
C: Lipopolysaccharide is the major component of the outer membrane of Gram-negative bacteria, not resistant to autoclaving.
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Which of the following statement is incorrect
- A. Antigens in tissues can reach regional LN via afferent lymphatic vessels
- B. Migrating dendritic cells that have collected antigens in tissues enter the draining LN via HEV
- C. During an infection fever and other inflammatory signals induce increased blood flow to draining LN and increased chances for lymphocytes to migrate from blood into LN
- D. The thoracic duct returns most of the circulating lymphocytes back to blood
Correct Answer: B
Rationale: The correct answer is B because migrating dendritic cells do not enter the draining lymph node (LN) via high endothelial venules (HEV); instead, they enter through afferent lymphatic vessels. HEVs are specialized post-capillary venules in LN where lymphocytes enter from the bloodstream. Dendritic cells, carrying antigens from tissues, travel via afferent lymphatic vessels to reach the LN where they present antigens to lymphocytes. Option A is correct as antigens in tissues reach LN via afferent lymphatic vessels. Option C is correct as infection-induced signals can increase blood flow to LN, facilitating lymphocyte migration. Option D is incorrect because the thoracic duct returns lymph back to the bloodstream, not specifically lymphocytes.
What type of dressing will the nurse most likely use for the patient in Question 14?
- A. Dry, sterile dressing
- B. Absorptive dressing
- C. Negative pressure wound therapy
- D. Telfa dressing with antibiotic ointment
Correct Answer: B
Rationale: Absorptive dressings are ideal for wounds with moderate exudate, helping maintain a moist environment conducive to healing while preventing maceration.
With respect to vaccination against a particular infectious disease 'herd immunity' refers to:
- A. The total number of people who are immunized in a given population
- B. The protection offered to non-immunized people when high rates of immunization prevent the pathogen from spreading
- C. The percentage of people who generate a protective response to the vaccine
- D. The tendency of people to choose to be vaccinated if close contacts (friends and family) have been vaccinated
Correct Answer: B
Rationale: The correct answer is B. Herd immunity refers to the protection offered to non-immunized individuals when a high percentage of the population is immunized, preventing the pathogen from spreading easily. This is because when a large portion of the population is immune to a disease, it creates a barrier that reduces the overall transmission of the pathogen, thus protecting those who are not vaccinated or cannot be vaccinated.
Choice A is incorrect because herd immunity is not solely about the total number of immunized individuals, but rather about the impact on the entire population. Choice C is incorrect as it refers to the efficacy of the vaccine in generating a protective response, not the concept of herd immunity. Choice D is incorrect as it relates to social influence rather than the collective protection provided by high rates of immunization.
According to the hygiene hypothesis, which of the following factors protect us from developing immune diseases?
- A. Small family size
- B. Good sanitation
- C. Low antibiotic use
- D. Living in "westernized" countries
Correct Answer: C
Rationale: The correct answer is C: Low antibiotic use. The hygiene hypothesis suggests that reduced exposure to infections, which can happen with low antibiotic use, can lead to an increased risk of immune diseases. Antibiotics can disrupt the balance of gut microbiota, which plays a crucial role in immune system development. A: Small family size may not necessarily protect against immune diseases as it does not directly relate to exposure to infections. B: Good sanitation can reduce the spread of infections but may not necessarily protect against immune diseases. D: Living in "westernized" countries is a broad factor and does not directly address the impact of low antibiotic use on immune diseases.
A 28-year-old male Gulf War veteran tells the nurse he gets a headache, sore throat, shortness of breath, and nausea when his girlfriend wears perfume and when he was painting her apartment. He is afraid he has cancer. What does the nurse suspect may be the patient’s problem?
- A. He has posttraumatic stress disorder.
- B. He has multiple chemical sensitivities.
- C. He needs to wear a mask when he paints.
- D. He is looking for an excuse to break up with his girlfriend.
Correct Answer: B
Rationale: Multiple chemical sensitivities could explain the patient's symptoms triggered by exposure to various chemicals.