The hypervariable regions

Correct Answer: A

Rationale: Step 1: Hypervariable regions are responsible for antigen binding specificity. Step 2: Complementary Determining Regions (CDRs) are the specific locations within the hypervariable regions. Step 3: As CDRs are part of the hypervariable regions, choice A is correct. Summary: Choices B, C, and D are incorrect because hypervariable regions are not in the constant region, are present in secreted antibodies, and are found in both heavy and light chains.

Correct Answer: A

Rationale: The correct answer is A: Red blood cell. Red blood cells, also known as erythrocytes, contain hemoglobin that binds to oxygen and carbon dioxide for transport in the bloodstream. They are specifically designed for gas exchange. White blood cells (B) are part of the immune system and fight infections. Platelets (C) are responsible for blood clotting. Hematocrit (D) refers to the proportion of red blood cells in the blood, not a specific type of cell responsible for gas transport.

Correct Answer: C

Rationale: The correct answer is C: Hemorrhage. Hemorrhage refers to excessive bleeding. Thrombosis (A) is the formation of blood clots, not excessive bleeding. Embolus (B) is a blood clot that travels through the bloodstream and blocks a blood vessel. Hemostasis (D) is the process of stopping bleeding, not the term for excessive bleeding. In summary, only choice C directly relates to the medical term for excessive bleeding.

Correct Answer: C

Rationale: The correct answer is C: Charles Janeway. He proposed the existence of pattern recognition receptors on innate cells in the 1980s, leading to the development of the concept of innate immunity. Janeway's hypothesis revolutionized our understanding of immune responses by emphasizing the role of pattern recognition in detecting pathogens. Tonegawa is known for his work on immune diversity; Metchnikoff discovered phagocytes; and Steinman identified dendritic cells. Janeway's contribution to immunology specifically focuses on pattern recognition receptors, making him the correct choice for this question.

Correct Answer: D

Rationale: The correct answer is D: IL-8. IL-8 is not a systemic cytokine because it mainly acts locally at the site of inflammation to recruit neutrophils. Systemic cytokines like TNF, IL-1, and IL-6 have widespread effects throughout the body, influencing various immune responses and inflammatory processes. IL-8's localized action distinguishes it from systemic cytokines, making it the correct choice. TNF, IL-1, and IL-6 are all systemic cytokines that play key roles in regulating the immune response and inflammation at a systemic level, unlike IL-8.