Final answer:
Hematocrit measures the volume percentage of erythrocytes in a blood sample after centrifugation, indicating the red blood cell count. Changes in the components of blood can alter the hematocrit value; for instance, an increase in RBCs or loss of plasma increases hematocrit. This measure is critical for diagnosing various health conditions.
Step-by-step explanation:
Hematocrit is the volume percentage of erythrocytes, or red blood cells (RBCs), in a given sample of blood after it has been centrifuged.
When blood is centrifuged, the erythrocytes settle at the bottom, above which is the 'buffy coat' containing white blood cells (leukocytes) and platelets (thrombocytes), and above this is the plasma.
The hematocrit value is important because it provides information about the number of red blood cells in the blood, which can indicate numerous health conditions, including dehydration, anemia, and other blood disorders.
Altering the different components of blood can significantly affect the hematocrit. For example, if the body produces more RBCs or there is a loss of plasma volume due to dehydration, the hematocrit value would increase.
Conversely, if there are fewer RBCs due to blood loss or a disease that affects their production, the hematocrit would decrease.
Since plasma normally constitutes the majority of the blood's volume, if a patient's hematocrit is 42 percent, then approximately 58 percent of the blood is plasma.
It is important to note that the term 'formed elements' of blood (white blood cells, red blood cells, and platelets) is used because not all of these are cells in the classical sense.
Red blood cells lose their nucleus during maturation and platelets are cell fragments; thus, they are different from typical body cells which contain a nucleus and organelles.