Q- In which one of the following parts of the GIT most of the ingested iron is absorbed?
A- Stomach
B- Duodenum
C- Ileum
D- Ascending colon
E- Descending colon
B- Duodenum- The acidic environment of the stomach helps to solubilize iron from food, and then in the duodenum, iron absorption occurs primarily through active transport mechanisms.
Q- Which of the following are the major sites for heme synthesis?
A- Bone marrow and kidney
B- Bone marrow and liver
C- Bone marrow and spleen
D- Kidney and liver
E- Kidney and spleen
B- Bone marrow and liver- The bone marrow is responsible for producing heme for hemoglobin synthesis in red blood cells, while the liver synthesizes heme for various other heme-containing proteins, such as cytochromes involved in electron transport and enzymes like catalase and cytochrome P450.
Q- Which one of the following procoagulant factors is NOT produced by endothelial cells?
A- Fibrinogen
B- Prostacyclin
C- Thromboxane A2
D- von Willebrand’s factor (vWF)
A- Fibrinogen- Fibrinogen is not produced by endothelial cells. It is primarily synthesized by hepatocytes in the liver. It plays a crucial role in blood clotting by being converted into fibrin, which forms the structural basis of a blood clot. Prostacyclin is primarily synthesized by endothelial cells and acts as an inhibitor of platelet aggregation and a vasodilator. Thromboxane A2 is produced by activated platelets and endothelial cells. It promotes platelet aggregation and vasoconstriction. von Willebrand’s factor (vWF) is produced by endothelial cells, specifically endothelial cells lining blood vessels and by megakaryocytes in bone marrow. It plays a crucial role in hemostasis by mediating the adhesion of platelets to damaged blood vessel walls.
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