Plasma

Plasma is the fluid matrix of blood — a straw-coloured, viscous liquid that makes up the larger share of blood, close to 55 per cent of its total volume.

What plasma is made of

Most of plasma is simply water. Water accounts for about 90 to 92 per cent of plasma, while proteins make up roughly 6 to 8 per cent of it. Beyond water and proteins, plasma carries a range of dissolved substances that the body is constantly moving from place to place.

The plasma proteins

Three kinds of protein dominate plasma — fibrinogen, globulins and albumins — and each has its own job:

• Fibrinogen is required for the clotting (coagulation) of blood.
• Globulins are chiefly part of the body's defence mechanisms.
• Albumins help maintain the body's osmotic balance.

Other substances carried in plasma

Plasma also holds small quantities of minerals, including sodium, calcium, magnesium, bicarbonate and chloride ions. In addition, nutrients and materials that are always in transit through the body — such as glucose, amino acids and lipids — are dissolved in it. …