Hematology

Step 1: Understanding the role of heparin.
Heparin is an anticoagulant, which means it prevents clotting of blood by inactivating thrombin and other clotting factors. Therefore, when blood is collected in a heparinized tube, it does not form a clot even after standing or centrifugation.
Step 2: Centrifugation process.
When the sample is centrifuged, the heavier components such as red blood cells (RBCs) settle at the bottom of the tube due to gravity. A thin layer called the buffy coat, which consists of leukocytes (WBCs) and platelets, forms in the middle. The lighter component, plasma, remains at the top.
Step 3: Differentiating plasma from serum.
Plasma is the liquid part of unclotted blood and contains fibrinogen and clotting factors. Serum, on the other hand, is obtained only after blood clots. Since heparin prevents clotting, the separated liquid is plasma, not serum.
Step 4: Conclusion.
Thus, centrifugation of heparinized blood separates the components into plasma, buffy coat, and RBCs.
Final Answer:

Step 1: Recall the erythropoiesis stages.
Erythropoiesis is the process by which red blood cells (RBCs) are produced in the bone marrow. The process begins with a large immature cell (proerythroblast) and ends with a mature RBC.
Step 2: First stage – Proerythroblast.
The proerythroblast is the earliest recognizable precursor in the erythroid series. It is large, with a large nucleus and basophilic cytoplasm.
Step 3: Second stage – Basophilic erythroblast.
This cell is smaller than the proerythroblast and has strongly basophilic cytoplasm due to abundant ribosomes.
Step 4: Third stage – Polychromatic erythroblast.
At this stage, the cytoplasm begins to show mixed staining (blue + pink), due to decreasing ribosomes and increasing hemoglobin.
Step 5: Fourth stage – Orthochromatic erythroblast.
This cell is almost filled with hemoglobin, and the nucleus becomes pyknotic and eventually extruded.
Step 6: Fifth stage – Reticulocyte.
After enucleation, the cell becomes a reticulocyte, which still contains some ribosomal RNA. Reticulocytes mature into RBCs in circulation.
Step 7: Conclusion.
Thus, the correct sequence is: Proerythroblast → Basophilic erythroblast → Polychromatic erythroblast → Orthochromatic erythroblast → Reticulocyte.
Final Answer:

Step 1: Understanding venous drainage of kidney.
Venous blood from the kidney is collected first by the smallest veins known as cortical radiate veins. These veins then converge and drain into arcuate veins.
Step 2: Sequence of venous drainage.
The correct sequence of renal venous drainage is:
Cortical Radiate Veins Arcuate Veins Interlobar Veins Renal Vein.
Step 3: Identifying the final vein.
All the interlobar veins ultimately unite and drain into the renal vein, which is the last destination vein before entering the inferior vena cava.
Final Answer: