Blood Plasma

Plasma Components

There are three components of whole blood: red blood cellsThe basic structural and functional units of life., the Buffy coat, and plasmaThe liquid component of blood.. When you’re presented with whole blood, you receive all of these components. However, they are intermixed, making what appears to be a homogeneous mixture. That is whole blood. We can centrifuge whole blood which is a process that will separate out things by density. When we centrifuge whole blood, the very heavy red blood cells sink to the bottom. The platelets and white blood cells form a little tiny strip here in the center. Plasma, rich in proteinsLarge molecules made of amino acids with various functions in the body., ionsCharged atoms or molecules., and waterThe universal solvent essential for life., ends up floating on the top as the least dense of the components. 

Plasma, making up over half of blood volume, is mainly water mixed with proteins, electrolytes, nutrients, and waste products. Key plasma proteins include albuminA plasma protein that helps maintain osmotic pressure and transport substances. (maintains osmotic pressureThe force exerted by water moving across a membrane due to osmosis.), globulinsPlasma proteins involved in immunity, clotting, and transport. (antibodies and transport proteinsBind hormones for transport in the blood.), and fibrinogen plasma protein converted into fibrin during blood clotting. (clotting factor).

Blood drawn and placed in a bag would contain red blood cells, white blood cells, platelets, and plasma. Centrifuging blood organizes it into three layers by density. Plasma is at the top. White blood cells and platelets are in the middle. Red blood cells are at the bottom. Plasma is mostly water, making up about 55% of blood. It contains dissolved substances like proteins (albumin, globulins, fibrinogen), electrolytes (e.g., sodium(Na⁺): Major ECF cation; important for fluid balance, nerve function., potassium(K⁺): Major ICF cation; essential for muscle and nerve function., calcium), nutrients (e.g., glucoseA simple sugar that is the main source of energy for cells., lipidsOrganic molecules including fats, oils, and steroids.), and nitrogenous waste.

Albumin

There are a variety of different proteins present in the plasma of your blood. They can be classified or categorized in different ways.  We are going to focus on albumin as the most significant protein present in plasma. Albumin is a yellow colored protein that imparts its color to the straw like overall appearance of plasma. It is also albumin that turns the yolks of an egg yellow.  Because albumin is the protein present in the most abundance it contributes to the osmotic pressureThe force exerted by gases in the respiratory system, affecting airflow and gas exchange. of your blood. This means that albumin is responsible for keeping your blood in the blood vessels.  Seriously.  Albumin attracts watery components into blood vessel in your tissues.  This is a good thing!

Other Plasma Proteins

There is an immense amount of globulins that could be present in your plasma at any given time. Most globulin proteins are transporters of some sort such as transferrinA blood plasma protein that transports iron. that transports iron and the thyroid-binding globulin.  There are five classes of immunoglobulins(Ig) Antibodies: Proteins produced by the immune system to target specific antigens. which are more casually known as antibodies.

Rivaling the importance of albumin is a protein named fibrinogen. This protein is soluble in water and is also soluble in plasma. When needed fibrinogen can precipitate out of the plasma by turning into fibrinAn insoluble protein that forms the mesh of blood clots.. This allows it to glued together broken capillariesThe smallest blood vessels where gas, nutrient, and waste exchange occurs between blood and tissues. and basically act as a Band-Aid.

90% of your plasma proteins are made by the liverA large organ that produces bile, detoxifies blood, and stores nutrients.. So liver malfunction results in a drop of osmotic pressure of the blood. This ultimately leads to edemaExcess fluid in interstitial spaces.. It also causes a specific condition called ascites. In ascites, massive amounts of fluid accumulate in the peritoneal cavity. This is why many people who are nutritionally deficient have swollen bellies. Nutrition is of paramount importance in making plasma proteins.