Nokea
A small lesion is discovered in a patient’s lung when an x-ray is performed for cervical spine pain. What is the definitive method of determining if the lesion is malignant?
- A. Lung scan
- B. Tissue biopsy
- C. Oncofetal antigens in the blood
- D. CT or positron emission tomography (PET) scan
Correct Answer: B
Rationale: Tissue biopsy provides definitive diagnosis by examining the lesion's cellular characteristics.
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During the healing phase of inflammation, which cells would be mostly likely to regenerate?
- A. Skin
- B. Neurons
- C. Cardiac muscle
- D. Skeletal muscle
Correct Answer: A
Rationale: Skin cells are highly regenerative due to their rapid turnover rate and presence of stem cells. In contrast, neurons, cardiac muscle, and skeletal muscle have limited regenerative capacity.
Lymphokines are protein substances produced in small amounts by lymphocytes and move from cell to cell carrying message through the immune system. The most common lymphokine is:
- A. Vaccine
- B. Antigen
- C. Antibody
- D. Interferon
Correct Answer: D
Rationale: Rationale for Correct Answer (D - Interferon):
1. Lymphokines are protein substances produced by lymphocytes.
2. Interferon is a type of lymphokine produced by lymphocytes during viral infections.
3. It helps in regulating the immune response and inhibiting viral replication.
4. Interferon moves from cell to cell carrying messages through the immune system.
Summary of Incorrect Choices:
A: Vaccine - Not a lymphokine, but a substance used to stimulate the immune system.
B: Antigen - Not a lymphokine, but a substance that triggers an immune response.
C: Antibody - Not a lymphokine, but a protein produced by the immune system to neutralize pathogens.
Which of the following is NOT an outcome of complement activation:
- A. Increased recruitment of inflammatory cells
- B. Opsonization of pathogens
- C. Lysis of pathogens
- D. Increased migration of dendritic cells from tissues to lymph nodes
Correct Answer: D
Rationale: The correct answer is D: Increased migration of dendritic cells from tissues to lymph nodes. Complement activation does not directly lead to the migration of dendritic cells. Complement activation can lead to increased recruitment of inflammatory cells (A), opsonization of pathogens (B), and lysis of pathogens (C). Dendritic cells typically migrate to lymph nodes to present antigens to T cells, but this process is not directly mediated by complement activation.
What is the role of perforin released by NK cells?
- A. Activating B cells
- B. Forming pores in target cell membranes
- C. Engulfing pathogens
- D. Inducing inflammation
Correct Answer: B
Rationale: Perforin released by NK cells forms pores in target cell membranes, allowing for the entry of granzymes which induce target cell death. This process is crucial for the immune response against infected or abnormal cells. Activating B cells (A) is not the role of perforin, as B cells are primarily activated by antigens. Engulfing pathogens (C) is the role of phagocytes like macrophages, not perforin. Inducing inflammation (D) is not directly related to the function of perforin in forming pores in target cell membranes.
What type of receptor is found on B cells for antigen recognition?
- A. T cell receptor (TCR)
- B. B cell receptor (BCR)
- C. Fc receptor
- D. Complement receptor
Correct Answer: B
Rationale: The correct answer is B because B cells express B cell receptors (BCR) on their surface for recognizing antigens. BCRs consist of immunoglobulin molecules that bind specifically to antigens. T cell receptors (A) are found on T cells, not B cells. Fc receptors (C) bind to the Fc region of antibodies, while complement receptors (D) recognize complement proteins, not antigens. Therefore, the BCR is the specific receptor on B cells for antigen recognition.