Function and composition of blood
We begin this study session by describing the function of blood. The blood is considered by some to be the very essence of life itself. Before modern medicine, blood was viewed as magical. Today, blood still has enormous importance in the practice of medicine. Clinicians examine it more often than any other tissue when trying to determine the cause of a disease or a disorder.
In an adult human, blood accounts for approximately 7–9% of body weight. So for a person weighing 70 kg, some 5 to 6 litres of blood circulate around the body. The blood transports nutrients, oxygen and waste molecules from one place to another within the body.
Every living cell needs a continuous supply of oxygen and nutrients, and a means to remove waste products. Performing these needs is the primary function of the blood.