Platelet

platelet is also knon as thermbocyte.The main fun of thermbocyte is in clotting .

1. PLATELET Ms Ankita R Bhatiya Assistant Professor Shree P.M.Patel COLLEGE OF PARAMEDICAL SCIENCE N TECHNOLOGY

2. It include: 1.What is Platelet ? 2.Function of Platelet . 3.Production of Platelet. 4. Method for detection of Platelet.

3. Platelet INTRODUCTION : Platelet- Thrombocyte Derived from Greek Thrombo for “clot" and cyte translated as "cell" in modern usage. Non-nucleated formed elements in the blood. It contain Contains – Golgi apparatus, Endoplasmic reticulum, Mitochondria, microtubules, microvesicles , filament, granules, glycogen, Lysosomes , protein enzymes & hormonal substances in their cytoplasm. The platelet has yellowish clr .

4. Platelet Platelets – small plate like. Thrombocytes . – thrombo – clot; cytes —cells. Size – smallest blood cells ; 2-4 μ m. Shape – spherical or oval discoid Colour – colourless or yellowish Property of Platelets: Easy clumping. Sticking to water, wet surface or rough surface. Easy disintegration & liberation of thrombokinase .

5. FUNCTIONS Role in haemostasis : Spontaneous arrest of bleeding from injured blood vessel. Role in clot formation: Play imp role in formation of intrinsic prothrombin activator .It is responsible for onset of blood clotting. Role in clot retraction: Contraction of contractile proteins i . e Actin , Myosin & Thrombosthenin . Responsible for clot Retraction & wound healing.: Role in repair of injured blood vessels: Repair of capillary endothelium: While in the circulation, the platelet adheres to the damaged endothelium lining of the capillary & thus bring about speedy repair. Role in Defense mechanism. Due to the property of agglutination , platelets are capable of Phagocytosis . Mainly in Phagocytosis of carbon particles, viruses & immune complexes. When platelets are disintegrated 5HT (5 hydroxy tryptamine ) & Histamine are released. 5HT is a powerful vasoconstrictor

6. Normal range of platelet Normal count: 1.5 – 4.0 lakh / cumm Avg 2.5 L/ cumm PHYSIOLOGICAL VARIATIONS. Age – Less in infant, reach adult level by 3 months of age. Sex – No difference but during mensturation reduced in females. Meal – Increases after meal Muscular exercise – Increases. High Altitude – Increases .

7. FORMATION OF PLATELETS. Sites – Bone Marrow Stem cells – PHSC CFU- Meg Stages in platelets production.(10 days) Megakaryoblast . Promegakaryocyte . Megakaryocyte .

8. MEGAKARYOBLAST. Earliest recognizable cells. CFU-Meg differentiate to form Megakaryoblast . Diameter – 20-30 mm Cytoplasm – small, blue, Non-granular Nucleus – large, oval/kidney shaped

9. PROMEGAKARYOCYTE Megakaryoblast – Endoreduplication of nuclear chromatin. Nuclear chromatin replicates in multiple of 2 without division of cell. Large cell with 32 times diploid content of nuclear DNA formed. Cytoplasm – Granular

10. MEGAKARYOCYTE Diameter – large cell with 30-90mm in diameter. Nucleus- single multiloaded . Cytoplasm – abundant with red purple granules. Cell margin – irregular with many Pseudopodia which gets detached into blood & forms platelets. One Megakaryocyte 4000 platelets

11. LIFE SPAN & FATE OF PLATELETS. Life span – 8-12 days Avg – 10 days. Fate – Destroyed by tissue macrophage system in spleen. Splenomegaly – reduces platelet count. Splenectomy – increases platelet count .

12. Method for counting of platelet Aim: Determination of platelet count by Haemocytometry method. Clinical Significance: Increase platelet count during Thrombocytosis due to burns, polycythemia Vera, chronic myelogenouns leukaemia. Decreased platelet count during Thrombocytopenia is often associated with prolong bleeding, aplastic anaemia, megaloblastic anaemia, vitamin deficiency etc. Normal Range: 1.5 – 4.0 lakh / cumm

13. Method for counting of platelet Method: Haemocytometery Principle: Procaine hydrochloride diluting fluid partially lyses the red blood cells. The blood sample is diluted 1:200 with the help of platelet diluting fluid & the cells are counted under high power with the help of counting chamber. Requirements: Neubauer's chamber, microscope, Hb pipette, cotton. Platelet diluting fluid: It is prepared as follow: a. Procaine HC1: - 3.0 gm which lyses the RBC b. Sodium Chloride: - 10 gm c. Distilled water: - 100 ml Specimen: EDTA blood sample, Capillary blood

14. Procedure: 1. Identify the right patient. 2. Collect all the requirements. 3. Do the labelling . 4. In a labelled test tube take 1.98 ml of platelet diluting fluid in plastic tube. 5. Add 0.02 ml blood with the help of Hb pipette and use dry cotton to wipe excess blood outside the pipette. 7. Mix well & keep it for 5 min.

15. 8. Fill the counting chamber. Place the filled N.ch under a Petridis with a moist filter paper. Let it stay undisturbed for 15 min. (This permits the platelets to settle & also prevents evaporation of diluting fluid in the chamber) 9. Place the counting chamber carefully on the stage of the microscope first switch to low power objective & then high power objective. 10. Now count platelets in all 25 small squares platelets will appear like highly refractive particle named as P1...P25. 11. Put all the values in standard Formula do calculation. 12. Record the result. 13. Put all the requirements back to its place. 14. Clean the working area.

16. Method for counting of platelet Calculation: Platelets/ cumm = =----------- x2000 cells / cumm

17. Precaution: 1. Platelet count should be carried out within 2 hrs. of blood collection. Delay causes clumping & disintegration of platelet. 2. Platelet is very small in size. They agglutinate and breakup easily. They also tend to adhere to glassware & particles in the diluting fluid. Therefore, in order to obtain an accurate platelet count, use siliconized clean & dry syringes & blood collection bottles. 3. The counting chamber should be clean & dry. 4. Diluting fluid is drawn up to the mark & care is taken not to allow air bubbles to enter. 5. The filling of the chamber should be done in one application of the tip of the pipette. 6. Air bubbles should not be present under the coverslip . 7. The diluting fluid should not over run the coverslip . 8. Longer waiting leads to drying of the fluid and disturb the cells. 9. Before the counting the condenser & mirror of the microscope should be properly adjusted.