Physical Properties of Blood and Plasma
How much blood is in the human body?
The average adult has a blood volume of approximately 5 liters, which comprises about 8% of the body's weight. The osmolality (concentration of solutes in water) of blood is 275-295 milliosmoles per kg.
What is blood plasma?
Plasma is the straw-colored liquid component of blood. It is a protein-salt solution and acts as a suspension for red and white blood cells and platelets.
What is plasma made of?
Plasma constitutes approximately 55% of blood's volume and is comprised of:
- 90% Water
- 8% Protein
- 0.9% Inorganic Salts
- Sodium 135-146 mM
- Potassium 3.5-5.2 mM
- Calcium 2.1-2.7 mM
- Carbonate 23-31 mM
- Phosphate 0.7-1.4 mM
- 1.1% of organic substances
The protein content of plasma
It is estimated that plasma may contain as many as 40,000 different proteins from about 500 gene products. Approximately 1,000 proteins have been detected.
Plasma contains three major types of proteins: albumins, globulins, and fibrinogens.
- Albumins are the most abundant protein group present in blood plasma.
- Globulins can further be divided into α1, α2, β1, β2, and γ-globulins.
- Fibrinogen is the plasma protein coagulation factor.1
- The plasma proteins can be classified by their functionalities into three classes: proteolytic enzymes, protease inhibitors, and carrier proteins.
- Plasma contains 50-70 mg of protein per ml
- Approx. 70% Albumin (35-50 mg/ml)
- Approx. 10% IgG (5-7 mg/ml)
Blood Composition on the Cellular Level
For every 600 red blood cells, there are approximately 40 platelets and one white cell.
Red Blood Cells (Erythrocytes)
- Typically 4-8 x 106 cells per µl
- Composed approx 90% hemoglobin
- RBCs have a life-span of approx. 120 days before they are removed by the spleen