Platelet aggregation is an important event in hemostasis. Which of the following statement is true for platelet aggregation in vascular injury?

Correct Answer: C

Rationale: Platelets change their shape during platelet aggregation to form a plug at the site of vascular injury. This process involves platelets adhering to the injured blood vessel wall, becoming activated, and then changing shape to form a clot. Vasodilation is not an initial response, as vasoconstriction occurs to reduce blood loss. Clotting factors are essential for clot formation and play a significant role. Serotonin is released from platelets during aggregation but does not directly stimulate aggregation. The correct choice, C, directly correlates with the physiological process of platelet aggregation in response to vascular injury.

Correct Answer: C

Rationale: Virchow's node is a left supraclavicular lymph node that typically receives lymphatics from abdominal organs. The correct answer is C: prostate because the prostate is not an abdominal organ and does not drain into Virchow's node. The other choices, A: testes, B: stomach, and D: breast, all drain into the abdominal lymphatic system, making them potential sources of lymphatic drainage to Virchow's node.

Correct Answer: D

Rationale: In thrombasthenia, there is a deficiency or dysfunction of the glycoprotein IIb/IIIa receptor complex on platelets, leading to impaired platelet aggregation. This results in prolonged bleeding time due to ineffective platelet plug formation (choice A). Platelet count is typically normal (choice B). Platelet aggregation is defective (choice C). However, clotting time is not affected in thrombasthenia as it primarily involves platelet function, not the clotting factors involved in coagulation (choice D). Therefore, the correct answer is D.

Correct Answer: A

Rationale: Henoch-Schonlein purpura (HSP) is a vasculitis that primarily affects small blood vessels. Thrombocytopenia, which is a low platelet count, is not typically associated with HSP. Palpable purpura, intestinal intussusception, and acute diffuse glomerulonephritis are commonly seen in HSP due to immune-mediated inflammation of blood vessels, gastrointestinal involvement, and renal complications. Thrombocytopenia, on the other hand, is not a characteristic feature of HSP, making choice A the correct answer.

Correct Answer: A

Rationale: The correct answer is A, hyperchlorhydria. Pernicious anemia is characterized by vitamin B12 deficiency due to lack of intrinsic factor. Hyperchlorhydria refers to high stomach acid production, not a symptom of pernicious anemia. Premature graying of hair and gastric polyp are potential features of pernicious anemia. Anti intrinsic factor antibody presence in 60% of patients is a characteristic finding in pernicious anemia.