Blood is the main bodily fluid and responsible for transporting important nutrients, oxygen, carbon dioxide and waste products to and away from the cells. Plasma is the yellow liquid component of blood and constitutes 55% of the total blood volume.
Composition of blood vs plasma
Blood is composed of plasma and different kinds of cells- red blood cells (erythrocytes), white blood cells (leukocytes), and thromobocytes (platelets). The density of blood (1060 kg/m3) is very close to that of pure water (1000 kg/m3).
Plasma contains water (90%), proteins (albumin, fibrinogen and globulins), nutrients (glucose, fatty acids, amino acids), waste products (urea, uric acid, lactic acid, creatinine), clotting factors, minerals, immunoglobulins, hormones and carbon dioxide, i.e. all the components of blood except the red, white blood cells and thrombocytes. Components can either be dissolved (if soluble) or remain bound to proteins (if insoluble). Plasma has the density of 1025 kg/m3.
Differences in Function
Blood performs very important functions in the body. The main functions are listed below:
- Supply of oxygen (which is bound to haemoglobin in the red blood cells) and other important nutrients to tissues.
- Removal of carbon dioxide and other waste products away from the tissues.
- Circulation of white blood cells important for immunological functions.
- Clotting at sites of injuries or cuts.
- Regulation of temperature and pH of the body.
Plasma is the fluid component of blood and thus performs all the same functions. It specifically helps in:
- Maintaining the electrolytes and fluid balance of the blood.
- Serves as the protein reserve for the body.
- Aids in clotting.
- Immune functions.
- Transport of carbon dioxide, essential nutrients (organic, inorganic components and plasma proteins), hormones (bound to plasma proteins), waste (urea, uric acid and creatinine) and other substances (example drugs and alcohol) to and from the tissues.
Blood disorders include anemia (insufficient red cell mass), genetic disorders (thalassemia and sickle cell anemia), leukemia (type of blood cancer), haemophilia (inherited clotting disorder), infectious disorders (HIV, Hepatitis B and C, bacteremia, malaria, trypanosomiasis), and carbon monoxide poisoning. Other disorders include dehydration, atherosclerosis, and others.
Plasma shift can cause changes n the volume due to excessive drainage or addition of fluid. This change in volume may be caused by changes in fluid volume across capillary membranes. This shift can change the viscosity of blood, concentration of protein, concentration of red blood cells or changes in coagulation factors which may lead to clotting disorders.
Storage and Transport
Blood for transfusion can be stored in blood banks. Blood products such as platelets, blood plasma and coagulation factors can also be stored and administered intravenously.
Fresh frozen plasma can be store at -40C for up to 10 years. It contains all the coagulation factors and other proteins present in the blood, and can be used to treat coagulopathies (clotting and bleeding disorders) and liver diseases. Dried plasma was used during WWII, and provided for transfusions to soldiers in combat. This was replaced by serum albumin during the Korean War