The blood provides oxygen and essential nutrients to cells, tissue and organs throughout the human body. The blood also acts to remove excess waste from the body, enabling it to work more efficiently. The major immune cells of the body---platelets and red and white blood cells---float along the blood plasma as they travel through the body. The blood plasma is the liquid portion of blood and is composed of water, albumin, clotting factors and antibodies.
Water
The primary component of blood plasma is water. The American Association of Blood Banks (AABB) estimates that water makes up 90 percent of blood plasma. Blood plasma can provide water to body tissues that are in need of additional fluid or it can absorb excess water and pass it along to the kidneys to be excreted as urine.
Albumin
Albumin is the predominate protein present in blood plasma. This protein prevents blood fluid from inadvertently leaking out of blood vessels, explains the Merck Manual: Home Edition, a medical reference guide for patients and caregivers. Albumin also helps carry certain substances, such as hormones and ingested drug products, through the body to the appropriate cells and tissues.
Antibodies
Blood plasma contains a number of additional proteins called immunoglobulins or antibodies. Antibodies are part of your body's immune system and are produced by the white blood cells, explain health professionals at the National Blood Service in the United Kingdom. If bacteria or viruses invade your body, antibodies within your blood plasma help to identify and fight off infection.
Blood Clotting Factors
If you sustain an injury to your body, you can begin to bleed. The body uses blood clotting factors---which are major components of blood plasma---to prevent you from losing excessive amounts of this vital body fluid. Blood clotting factors, such as fibrinogen or Factor VIII, help the body seal damaged blood vessels and stop bleeding.
