What is Blood Plasma?

Mary McMahon
Mary McMahon

Blood plasma is the liquid component of blood, consisting of around half of the total blood volume. Plasma itself is around 90% water, with the 10% remainder including proteins, minerals, waste products, clotting factors, hormones, and immunoglobins. Without plasma, blood cells would have no medium to travel on as they moved through the body, and plasma also performs a number of other useful functions in the body.

A bag of blood plasma.
A bag of blood plasma.

Separating blood plasma from the blood itself is very easy. Blood can be drawn from the patient and then run in a centrifuge. As the blood spins, the heavier blood cells settle to the bottom, and the plasma rises to the top. Plasma is usually straw colored, although it can be cloudy or grayish, depending on the health and diet of the plasma's host. Tests can be performed on the plasma to learn more about the health of the donor, and the blood cells can also be analyzed for information.

Red blood cells exist in blood along with blood plasma.
Red blood cells exist in blood along with blood plasma.

As plasma circulates through the body, it acts like a milkman making deliveries. The plasma drops off various substances to the cells of the body, and collects waste products for processing. Blood plasma flows constantly, and the components of plasma are constantly being renewed. In addition to providing nutrition and waste cleanup, blood plasma also harbors immune system cells which attack infections in the body, and it is used to deliver hormones and clotting factors to areas where they are needed.

Blood plasma is separated from other components of blood via a centrifuge.
Blood plasma is separated from other components of blood via a centrifuge.

Doctors sometimes use infusions of plasma to treat a variety of medical conditions. Pure plasma contains clotting factors which increase the rate at which blood clots, making it useful in surgery and in the treatment of hemophilia. Frozen, plasma can keep for up to 10 years, making it an extremely stable blood product, and plasma can also be packaged in dried form for reconstitution, a technique which was developed for military applications. For hemophiliacs, packages of plasma combining clotting products from hundreds or thousands of donors are used to compensate for the clotting factors that the hemophiliac lacks.

During a blood plasma donation, blood is taken from the donor and the plasma is then separated from the rest of the blood.
During a blood plasma donation, blood is taken from the donor and the plasma is then separated from the rest of the blood.

In a medical process called plasmapheresis, plasma can be pulled out of the blood, treated, and returned to the patient to treat certain medical conditions. Plasmapheresis can also be used in plasma donation, allowing people to donate just plasma, without any blood cells. Since plasma is often in high demand, plasma donation is an excellent donation option for people who wish to contribute blood products to people in need. Plasma donation takes a little bit longer than regular blood donation, but the blood plasma replenishes itself within 48 hours, making for a very rapid recovery.

Red and white blood cells, platelets, and other components of blood flow in plasma inside a blood vessel.
Red and white blood cells, platelets, and other components of blood flow in plasma inside a blood vessel.
Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a wiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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Discussion Comments


I have Rheumatoid Arthritis. Is it OK to give me plasma?


@anon111345 - I'm pre-diabetic and I can still donate blood, so there shouldn't be a problem with donating plasma, although it depends on the rules in your area.

The only problem might be if you are taking medications. I've had them refuse me when I was taking an acne medication, so I'm not sure how they'd react to medications for diabetes. Just take a list of whatever you take, and have taken recently, in with you to the blood plasma center and talk to the nurse about it.


@anon235194 - It's used for a few different things. They can give it to burn victims who have lost a lot of fluid, but not necessarily a lot of blood. They can use it as emergency treatment for people who have lost blood when they don't have a suitable blood type handy. It's not an ideal replacement but it will help to replenish their fluid levels so their bodies have a chance to generate more red cells.

It contains antibodies that can be given to people who have bad immune systems and also for people who are having trouble with clotting.

I also know that my local blood bank would much prefer that I was giving blood plasma than whole blood, so I think it's more "in demand". But it takes longer to give (an hour vs. 20 minutes for whole blood) and you can give it once a month, so it's a bigger time commitment. Worth it, in my mind.


@anon305011 - I believe that plasma is neutral and doesn't have those markings. They are contained on the other blood cells. That's one of the reasons plasma is so valuable to doctors. It's easy to store and it can be used universally.

Unfortunately, it's not as "powerful" as full blood, because it can only add to the liquid in your veins, rather than increase the amount of oxygen the blood can carry. So, it can be a lifesaver, but can't be a full replacement for whole blood.


What happens when you are type A and they give you type B frozen plasma?


The green color usually occurs in women who are on birth control. I don't know why yours would have changed back in color. However I also know you can't go five days in a week. You can't go twice in a 48 hour period or three times in a week. Your body has to have time to replenish. --Green


But I still don't understand. What is it used for? Like is it a medication? An antidote? What?


If someone took poison and went through proper treatment and was feeling (normal means the patient's blood pressure, pulse, RBC are normal) but plasma comes in at 342. in this case, in how much time will it take for the plasma level to normalize?


why is it important for the blood plasma to have a constant concentration?


For what reasons should you not give plasma? I would like to do it but I am Type 2 diabetic. Am I able to give?


From the articles I have read, the color of plasma is usually yellow but I suppose it could be any shade of color depending on body chemistry and the amount of substances that flow through blood.

Overall, it is a yellowish color but for the most part any shade of color would not matter because of the consistency factors of what is is used for. For the makeup of it, all plasma is needed to coagulate blood when ever we get a wound, or during surgery and we are bleeding or something like that.

The amount of plasma in the blood helps it for a barrier around the rest of the cells so the flow stops outside our skin,, but not inside per se. Because blood flow in the body is good.

Blood flow outside the body or blood leaving the body? Not good. And since plasma reacts so well with oxygen and air outside the body its almost like having an invisible shield to protect us when ever we get cut or during a surgery. Because when the blood touches the air outside our body its suppose to clot up to protect us so we don't keep bleeding. We are constantly bleeding inside; we just don't want to bleed outside.

Plasma stops all the bleeding on the outside. So who cares what color it is. Color does not matter. It's what it does that matters. Plasma is the warrior in all things in the body. Its basically like the Achilles of blood cells.


what is the role of plasma in the blood?


I am wondering if there has been any sequential design research on those that have been plasma donors? Am I at any higher of a risk for later health problems by being a donor?


Why was my plasma dark green after plasmapheresis? i went for five days last week. it was my first time with this technician and I could not get a response at the clinic. the green color did become less green each day until it was yellow on the last day. What was happening? I am a nurse. Thank you for any any information you give me.


Minerals such as potassium, sodium and calcium are transported by blood plasma.

So when we eat a banana and different parts of the body break down the food, it will be blood plasma that will transport potassium to where it is needed, such as the heart where it is needed for heart's proper functioning.

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