Final answer:
A typical blood sample consists of about 45% red blood cells and 55% plasma. When a patient has a hematocrit of 42%, around 58% of the blood is plasma. Plasma includes water, proteins, glucose, ions, hormones, and gases.
Step-by-step explanation:
A blood sample is usually about 45% red blood cells (erythrocytes) and 55% plasma. When a patient's hematocrit is measured at 42 percent, it indicates that 42 percent of their blood volume is constituted by erythrocytes.
Since erythrocytes make up a significant volume of the blood, the remaining percentage, which is approximately 58 percent in this case (since 42 plus 58 equals 100 percent), would be the plasma. Normally, plasma makes up about 55 percent of total blood volume, which includes water, dissolved proteins, glucose, ions, hormones, and gases. The plasma component is critical as it not only transports cells but also delivers nutrients to cells and carries waste products away.
Blood plasma is a golden-yellow liquid that is about 90 percent water and about 10 percent other substances. The specific gravity and packed cell volume (PCV) or hematocrit can vary based on factors such as gender and other physiological variables. Thus, approximately 55 percent plasma is a standard reference point for the liquid portion of blood.