Blood and Hematocrit

Erythrocytes

Use hemoglobin to carry oxygen to tissues throughout the body. They are the most abundant formed element in the blood.

Leukocytes

Have various immune functions and include granulocytes (neutrophils, eosinophils, basophils) and agranulocytes (lymphocytes, monocytes). They can travel out of blood vessels into tissues by diapedesis.

Platelets

Critical in blood clotting.

Hematocrit Step 1

Place a capillary tube into a blood sample to draw up blood.

Hematocrit 2

Centrifuge the capillary tube.

Hematocrit Calculation

Measure the length of RBCs, WBCs, and plasma in the tube and divide each by the total length of the fluid in the tube.

Blood Centrifugation

Erythrocytes sink to the bottom, the buffy coat (leukocytes and platelets) forms a thin layer in the middle, and plasma rises to the top.

Leukocytosis

Leukocyte count is too high; buffy coat >1%. Caused by infection and some types of leukemia.

Anemia

Erythrocyte count is too low; hematocrit value below average.

Types of Anemia

Aplastic anemia, iron-deficiency anemia, hemolytic anemia, sickle cell anemia. Hemorrhagic anemia is not detected by hematocrit.

High Altitude & Hematocrit

Individuals at high altitude have higher hematocrit due to lower oxygen levels.

Dehydration

Decreases plasma percentage due to the loss of water.

Blood Formed Elements

Formed Elements

Hematocrit

Height of RBC/height of all components of the blood x100

Hematocrit Range

Normal Adult Female Range: 37 – 47% Normal Adult Male Range: 42 – 52% Normal Newborn Range: 49 – 61%