ENGL 003- Midterm Exam Guide - Comprehensive Notes for the exam ( 26 pages long!)
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Determination of hematocrit value (hct) (packed cell volume = pcv) The haematocrit value or (pcv) is the % ratio of the rbcs volume to the total blood volume (fig. Fig. (1): components of blood after centrifugation: wintrobe tube (length 10 cm, internal diameter 2. 5 mm, centrifuge apparatus. Steps: venous blood anticoagulated with edta or na citrate is placed in wintrobe tube, centrifuge the tube at 3000 r. p. m for 15 minutes. Note that the blood is separated into 3 layers: rbcs are precipitated in the bottom, followed by thin grayish white layer (buffy coat) of wbcs and platelets followed by a clear plasma layer above (fig. 1): calculate the volume of packed cells/100cc blood, microhematocrit method: Equipments: heparinized capillary tubes (length 75 mm and internal diameter 1 mm, centrifuge apparatus, haematocrit ruler. Microhaematocrit is easier, more accurate and use a small amount of blood (commonly used in newly born infants) Fig. (2): steps of measurment of haematocrit by capillary tube.