Nokea
Identify the fluid that is least possible to transmit AIDS.
- A. Blood
- B. Breast milk
- C. Semen
- D. Saliva
Correct Answer: D
Rationale: The correct answer is D: Saliva. Saliva has very low levels of HIV, making it least likely to transmit AIDS. HIV transmission requires direct contact with infected bodily fluids containing high viral loads, such as blood, breast milk, and semen. Saliva does not typically contain enough HIV to transmit the virus, as it has enzymes that can inhibit HIV. Therefore, the risk of HIV transmission through saliva is extremely low compared to the other fluids listed.
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APECED is a rare autoimmune disease caused by deficiency of
- A. CTLA-4
- B. AIRE
- C. Tregs
- D. TGF-β
Correct Answer: B
Rationale: The correct answer is B: AIRE. APECED (Autoimmune Polyendocrinopathy-Candidiasis-Ectodermal Dystrophy) is caused by mutations in the AIRE gene. AIRE is responsible for regulating the expression of self-antigens in the thymus, crucial for the development of immune tolerance. Deficiency in AIRE leads to the production of autoantibodies and autoimmune manifestations.
Incorrect options:
A: CTLA-4 is involved in downregulating immune responses but is not directly linked to APECED.
C: Tregs (regulatory T cells) play a role in immune tolerance, but APECED is not directly caused by their deficiency.
D: TGF-β is a cytokine involved in immune regulation, but its deficiency does not lead to APECED.
Compared to naïve T cells, memory T cells:
- A. Take less time to become activated
- B. Have less need for costimulation during activation
- C. Have a much longer life span
- D. All of the above are correct
Correct Answer: D
Rationale: Memory T cells, compared to naïve T cells, take less time to become activated as they have previously encountered the antigen. They also have less need for costimulation during activation due to their enhanced sensitivity. Furthermore, memory T cells have a much longer life span, allowing for a more rapid and robust immune response upon re-exposure to the antigen. Therefore, all of the statements in choices A, B, and C are correct, making option D the correct answer.
Which T cell type helps activate B cells?
- A. Cytotoxic T cells
- B. Helper T cells
- C. Regulatory T cells
- D. Memory T cells
Correct Answer: B
Rationale: The correct answer is B: Helper T cells. Helper T cells play a crucial role in activating B cells by releasing cytokines that stimulate B cell proliferation and differentiation into plasma cells, which produce antibodies. Cytotoxic T cells (A) are involved in directly killing infected cells. Regulatory T cells (C) suppress immune responses. Memory T cells (D) are responsible for maintaining immunological memory for future responses. Thus, Helper T cells are the key cell type that helps activate B cells.
Defensins are
- A. Released by mast cells during an allergic reaction
- B. Membrane-disrupting peptides
- C. Acute phase proteins
- D. Opsonins
Correct Answer: B
Rationale: The correct answer is B: Membrane-disrupting peptides. Defensins are antimicrobial peptides that disrupt bacterial cell membranes. This disrupts the integrity of the bacterial cell, leading to cell lysis and death. Choice A is incorrect because mast cells release histamines, not defensins. Choice C is incorrect as acute phase proteins are involved in the immune response to inflammation. Choice D is incorrect as opsonins are molecules that enhance phagocytosis of pathogens by immune cells.
Cardiac output
- A. coronary insufficient circulation
- B. A defect in one or more heart valves
- C. Disorder in a heartbeat
- D. Amount of blood/minute pumped into systemic circuit
Correct Answer: D
Rationale: The correct answer is D because cardiac output refers to the amount of blood pumped by the heart into the systemic circulation per minute. It is a crucial measure of heart function. Option A, coronary insufficient circulation, specifically refers to inadequate blood flow to the heart muscle itself, not overall cardiac output. Option B, a defect in heart valves, would affect the efficiency of blood flow but not necessarily the total amount of blood pumped. Option C, a disorder in heart rhythm, relates to irregular heartbeat patterns rather than the volume of blood pumped. Therefore, D is the correct choice as it directly relates to the definition of cardiac output.