Nokea
A heart attack is
- A. damage to cardiac muscle
- B. Typically from a blocked coronary artery
- C. Death of brain tissue from blocked arteries in the head
- D. A & b
Correct Answer: D
Rationale: The correct answer is D because a heart attack, also known as a myocardial infarction, involves damage to the cardiac muscle due to a blocked coronary artery. Choice A is correct as it directly relates to the definition of a heart attack. Choice B is also correct as a blocked coronary artery is the main cause of decreased blood flow to the heart muscle leading to a heart attack. Choice C is incorrect as it refers to a stroke, which is the death of brain tissue due to blocked arteries in the head, not a heart attack. Therefore, A & B (choices A and B) are the correct options, making D the correct answer.
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Which of the following statements is true?
- A. MHC class I and MHC class II molecules both consist of two transmembrane protein chains
- B. MHC class I molecules have one peptide-binding site whereas MHC class II molecules have two peptide-binding sites
- C. A given MHC molecule binds only one peptide at a time
- D. MHC molecules on the cell surface have empty peptide-binding sites in the absence of infection
Correct Answer: C
Rationale: The correct answer is C because a given MHC molecule can bind only one peptide at a time. This is essential for the proper presentation of antigens to immune cells. MHC class I and class II molecules do not consist of two transmembrane protein chains (A), MHC class I molecules have one peptide-binding site while MHC class II molecules have one peptide-binding site (B), and MHC molecules on the cell surface typically have peptides bound to their peptide-binding sites, even in the absence of infection (D).
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.
What accurately describes passive acquired immunity (select all that apply)?
- A. Pooled gamma globulin
- B. Immunization with antigen
- C. Temporary for several months
- D. Immediate, lasting several weeks
Correct Answer: C
Rationale: Passive acquired immunity involves the transfer of antibodies from one individual to another, such as pooled gamma globulin, maternal immunoglobulins, and immediate protection that lasts for weeks to months.
What distinguishes NK cells from other lymphocytes?
- A. They are part of adaptive immunity
- B. They do not require prior antigen sensitization
- C. They directly produce antibodies
- D. They phagocytose pathogens
Correct Answer: B
Rationale: The correct answer is B because NK cells do not require prior antigen sensitization to recognize and attack infected cells. This distinguishes them from other lymphocytes, such as T and B cells, which are part of adaptive immunity and require prior exposure to specific antigens. NK cells are part of innate immunity and can directly recognize and kill infected or abnormal cells without prior activation. Choices A, C, and D are incorrect as NK cells are not part of adaptive immunity, do not directly produce antibodies, and do not phagocytose pathogens.
What cytokine is produced by Regulatory T cells to suppress immune responses?
- A. IL-2
- B. IL-10
- C. IFN-gamma
- D. TNF-alpha
Correct Answer: B
Rationale: The correct answer is B: IL-10. Regulatory T cells produce IL-10 to suppress immune responses by inhibiting the activation and function of other immune cells. IL-2 (A) is mainly produced by activated T cells to promote proliferation. IFN-gamma (C) is produced by T cells and NK cells to enhance immune response. TNF-alpha (D) is produced by macrophages and T cells to induce inflammation. IL-10 stands out as the suppressor cytokine in this context.