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Respiration and Circulation — BIOLOGY STD 12 Science — Question

Maharashtra BoardEnglish MediumSTD 12 ScienceBIOLOGYRespiration and Circulation3 Marks
Question
Describe the structure and the function of thrombocytes.
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Answer

  1. Thrombocytes or platelets are non- nucleated, round and biconvex blood corpuscles.
  2. They are smallest corpuscles measuring about 2.5 to 5 mm in diameter with a count of about 2.5 lakhs/cu mm of blood.
  3. Their life span is about 5 to 10 days.
  4. Thrombocytes are formed from megakaryocytes of bone marrow. They break from these cells as fragments during the process of thrombopoiesis.
  5. Thrombocytosis is the increase in platelet count while thrombocytopenia is decrease in platelet count.
  6. Thrombocytes possess thromboplastin which helps in clotting of blood.
  7. Therefore, at the site of injury platelets aggregate and form a platelet plug. Here they release thromboplastin due to which further blood clotting reactions take place.

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