Blood plasma (at the top)
Blood plasma is one of the components of blood. Excluding white blood cells, red blood cells and platelets, what remains is blood plasma. Plasma corresponds to approximately 55% of the composition of human blood.
Blood plasma performs very important functions in the human body. The main ones are: maintenance of osmotic blood pressure; acting through antibodies in the body's defense system; formation of blood clots. It is also very important as it is one of the main water reserves of the human body.
Main features and composition
- It's a yellowish liquid.
- Consists of: 91% water, 7% protein and 2% non-protein solutes (mainly fats, vitamins, gases, electrolytes, hormones, glucose and waste products).
- There are three main types of plasma proteins: albumin, globulin and fibrogen.
- It is a viscous liquid (its viscosity is about one and a half times higher than water).
- It's slightly salty.
- Albumin: accounts for just over half of the proteins present in plasma (about 55%). It acts in the maintenance of osmotic blood pressure.
Globulins: About 37% of the proteins in plasma are globulins. These proteins include immunoglobulins, antibodies of major importance in the immune system of humans.
- Fibrinogen: makes up about 8% of plasma proteins. It is of fundamental importance as it acts in the process of blood clotting. This helps to stop external and internal bleeding.
Did you know?
Plasma in human blood is produced in various parts of the body. Most plasma proteins are synthesized in the liver. Already hormones, present in plasma, are secreted by endocrine glands.
Last reviewed: 12/14/2018
By Elaine Barbosa de Souza
Undergraduate student in Biological Sciences, Methodist University of São Paulo.