How it works
The upper drawing is a blood smear: one each of the five white cells among the red cells and platelets. The lower one, a spun tube and a red cell cut in half, suits a class that wants unlabelled diagrams of a blood cell.
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Word bank for the unlabeled formed elements
Smear, seven: erythrocyte (red blood cell), neutrophil, eosinophil, basophil, lymphocyte, monocyte, platelets (thrombocytes). Tube and cut cell, three: plasma, cell membrane, hemoglobin. A class may write leukocyte for any white cell; on this sheet each one takes its own name.
Which parts have a line
Four: lymphocyte, platelets, cell membrane and hemoglobin. The other four white cells take their name inside or just under the cell, and any red cell on the smear will do for erythrocyte. Plasma goes on the clear layer at the top of the tube. The narrow band beneath it takes no label.
- On paper a red cell is a ring inside a ring. The inner ring is the thin center of the disc, not a nucleus.
- A cell with a nucleus on the smear is a white cell: red cells and platelets have none.
Questions and answers
What is the order of white blood cells from most to least common?
Neutrophils, lymphocytes, monocytes, eosinophils, basophils. Students keep the order with the phrase Never Let Monkeys Eat Bananas. The smear on this sheet has one of each, so it does not show the proportions.
What is the buffy coat?
The thin, pale layer that settles between the plasma and the red cells when blood is spun in a tube. The white blood cells are found in it. On the sheet it is the narrow band under the plasma.
What is the difference between plasma and serum?
Plasma is the liquid part of blood, mostly water, in which the formed elements are carried. Serum is plasma with the clotting proteins removed.
Are platelets cells?
No. Platelets are fragments of cells and have no nucleus. The term formed elements covers them together with the two kinds of blood cell, red and white.