What is blood?
Blood is a liquid tissue that flows around the human body through the blood vessels. It is made up of red blood cells, white blood cells and platelets which are suspended in a liquid called plasma. Blood plays a crucial role in transporting oxygen, nutrients, antibodies and hormones around the body.
Adults have an average blood volume of approximately 5 litres, although this volume varies depending on the individual person’s weight, height and gender.
The composition of the blood is as follows:
• 45% cells (red blood cells, white blood cells and platelets)
• 55% plasma (the liquid part)