Final answer:
Approximately 58% of a patient's blood is plasma if their hematocrit is 42 percent. Hematocrit represents the proportion of red blood cells, with the remaining volume being plasma.
Step-by-step explanation:
If a patient's hematocrit is 42 percent, this indicates the percentage of blood volume occupied by red blood cells. Since hematocrit is the proportion of blood composed of red blood cells, and the remainder is plasma, we can deduce that plasma makes up the rest of the total blood volume. To calculate the percentage of blood that is plasma, subtract the hematocrit percentage from 100%. Therefore, the plasma would make up approximately 58 percent of the patient's blood.
This understanding comes from knowledge of blood composition, where blood is generally composed of both cellular elements (like red and white blood cells, and platelets) and plasma. The hematocrit level gives us valuable insight into the proportion of these components. Given that the average hematocrit levels in humans range from about 38-50% for males and 34-45% for females, a hematocrit of 42 percent falls within the typical range.
Understanding blood composition is crucial for interpreting various medical tests and managing health conditions, as different components of the blood can indicate distinct aspects of an individual's health status.