Question

Critical count of platelet is
A. $40,000{\text{ }}/{\text{ }}m{m^3}$
B. $1{\text{ }}lac{\text{ }}/{\text{ }}m{m^3}$
C. $2{\text{ }}lac{\text{ }}/{\text{ }}m{m^3}$
D. $4{\text{ }}lac{\text{ }}/{\text{ }}m{m^3}$

Answer 1

If a person does not have enough platelets in their blood they are suffering from thrombocytopenia. A healthy person has platelet count of $150,000{\text{ }}to{\text{ }}400,000.$
In thrombocytopenia platelets count fall from $150,000.$

Complete answer:
Platelets are the blood clotting cells of mammals produced by the megakaryocytes; the special kind of cells present in the bone marrow. Normal count of platelets in a blood are 1,500,00 - 3,500,00 mm3 platelets. The shape of the platelets is irregular and they release a variety of substances most of which are involved in the clotting or coagulation of blood.
Size of the platelet is $1.5$u in diameter and life span is $7{\text{ }}to{\text{ }}10$ days.

The main function of platelets is coagulation. Platelets release a substance called thromboplastin which initiated the coagulation or clotting of blood. Increase in the number is known as thrombocytosis, and decrease in the number of platelets is called thrombocytopenia.

A reduction in the number of platelets can lead to clotting disorders which will lead to excessive loss of blood from the body.
Critical value of blood platelets is $40,000{\text{ }}/{\text{ }}m{m^3}$.

Thrombocytes are also platelets and are present in the non-mammalian vertebrates like reptiles, aves, etc. Thrombocytes are formed from the megakaryoblast cells of bone marrow.

Hence, the correct answer is option (A).

Note:

1. Erythrocytes, leukocytes and platelets formed $45\%$of blood.
2. Erythrocytes are red blood cells (RBC) and are most abundantly present in blood.
3. Leucocytes are the white blood cells (WBC) and are colorless because they lack hemoglobin.