Nokea
An example of a preformed chemical barrier is:
- A. Mucus
- B. Lysozyme
- C. Tight junctions in epithelial cells
- D. Cilia in the respiratory tract
Correct Answer: B
Rationale: Step-by-step rationale:
1. Lysozyme is an enzyme that destroys bacterial cell walls.
2. This action acts as a preformed chemical barrier against pathogens.
3. Mucus (choice A) is a physical barrier, not a preformed chemical one.
4. Tight junctions (choice C) and cilia (choice D) are structural components, not chemical barriers.
Summary:
- Choice B, Lysozyme, is correct as it actively targets and destroys pathogens.
- Choices A, C, and D are incorrect as they do not directly function as preformed chemical barriers.
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Individuals unable to make the J protein found in certain immunoglobulins would be expected to have frequent infections of the
- A. intestinal tract
- B. blood.
- C. liver.
- D. pancreas.
Correct Answer: A
Rationale: The correct answer is A: intestinal tract. The J protein is crucial for the proper functioning of immunoglobulins in the mucosal immune system, which plays a major role in defending against pathogens in the intestinal tract. Without the J protein, individuals would have impaired immune responses in the gut, leading to frequent infections in the intestinal tract. Choices B, C, and D are incorrect because the J protein deficiency specifically affects the mucosal immune system in the intestinal tract, not the blood, liver, or pancreas.
Find the unmatched pair with respect to immune function:
- A. Interferons: protection from viral infections
- B. ROS: killing of engulfed pathogens
- C. Mast cells: acute phase response
- D. Selectins: role in leukocyte extravasation
Correct Answer: C
Rationale: The correct answer is C: Mast cells: acute phase response. Mast cells are actually involved in allergic responses, not the acute phase response of the immune system. The acute phase response is primarily mediated by cytokines and acute-phase proteins. Interferons protect against viral infections, ROS help kill pathogens inside cells, and selectins aid in leukocyte extravasation during inflammation.
Which of the following is a major site of immune complex deposition in systemic lupus erythematosus (SLE)?
- A. Thyroid
- B. Glomerular basement membrane
- C. Peripheral nerves
- D. Mast cells
Correct Answer: B
Rationale: The correct answer is B: Glomerular basement membrane. In SLE, immune complexes deposit in various tissues, leading to inflammation and damage. The glomerular basement membrane is a common site for immune complex deposition in SLE, resulting in lupus nephritis. The other choices are incorrect because immune complex deposition does not typically occur in the thyroid, peripheral nerves, or mast cells in SLE. Thyroid involvement in SLE is more related to autoimmune thyroiditis, while peripheral nerves are not a major site for immune complex deposition in this condition. Mast cells are primarily involved in allergic reactions and are not a major target in SLE.
Which of the following is NOT an example of a pathogen-associated molecular pattern (PAMP)?
- A. Lipopolysaccharide (LPS)
- B. Peptidoglycan
- C. Viral RNA
- D. MHC molecules
Correct Answer: D
Rationale: The correct answer is D, MHC molecules. PAMPs are conserved molecules found on pathogens that can trigger an immune response. MHC molecules are not PAMPs; they are part of the host's immune system used to present antigens to T cells. LPS, peptidoglycan, and viral RNA are examples of PAMPs as they are specific molecules found on pathogens that can be recognized by pattern recognition receptors on immune cells to initiate an immune response.
Which of the following statements is NOT true?
- A. A B cell epitope will often be destroyed by denaturation
- B. A pathogen will often have more than one B cell epitope
- C. A B cell epitope is the part of the antibody molecule that contacts an antigen
- D. B cell epitopes are most commonly found on the surface of pathogens
Correct Answer: C
Rationale: The correct answer is C because a B cell epitope is not a part of the antibody molecule that contacts an antigen. B cell epitopes are specific regions on an antigen that bind to B cell receptors. Choice A is incorrect because denaturation can expose B cell epitopes. Choice B is incorrect because pathogens typically have multiple B cell epitopes. Choice D is incorrect because B cell epitopes can be found on various parts of pathogens, not just on the surface.