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What is Blood Made of?

Lauren Frame April 26, 2021

Your blood is made from plasma and blood cells. The four main components, plasma, red blood cells, white blood cells, and platelets work together to keep your body running smoothly. Each part plays a vital role, essential for your overall health.

Plasma is the liquid portion of our blood and is about 90% water. The plasma portion of your blood accounts for more than half of your blood volume.

As your heartbeats, the liquid plasma helps carry these blood cells throughout our body’s vast network of blood vessels – veins, arteries and capillaries – allowing them to perform their individual functions.

Blood Cells

Red Blood Cells

  • Red blood cells contain hemoglobin, which allows the cells to carry oxygen from our lungs throughout our body. They also return carbon dioxide to the lungs.
  • About 40% of our blood is made up of red blood cells.
  • Red blood cells can live about 120 days in our bloodstream.

White Blood Cells

  • White blood cells help our body fight off infection.
  • These cells have a nucleus, unlike red blood cells and platelets.
  • Only about 1% of our blood is made up of white blood cells.
  • An increased number of white blood cells in your blood often indicates disease or illness.


  • Platelets help form clots and control bleeding. These tiny cells travel to the site of an injury, sticking to the blood vessel walls to essentially plug up the injury and helping stop bleeding.
  • The majority of your platelets, about 70%, travel throughout your bloodstream. The remaining 30% are stored in your spleen.
  • About 38% of platelet donations are used for cancer patients.
  • They survive in our system for about seven to 10 days.


Whole Blood Donation

When you donate whole blood, the red blood cells, platelets and plasma are separated into three different blood products to be used for various patient needs.

Plasma Donation

Plasma is collected through a process called automation (sometimes referred to as apheresis). This technology enables us to collect plasma and/or plasma and platelets and not the donor’s red blood cells. The process separates the plasma from your other blood components, then safely and comfortably returns your red blood cells and platelets to you.

Double Red Cell Donation

Red cell donations are also collected using automation. This allows donors to give twice the amount of red cells compared to a whole blood donation.

Platelet Donation

Platelet donations are also done using automation. The machine collects your whole blood and then separates out your platelets. Your red blood cells, plasma, and some fluids are returned to you.

One automated platelet donation produces one or more complete platelet doses for a patient. It would take six to eight whole blood donors pooled together to produce one complete platelet dose.

Now that your know all about blood, we invite you to come in and share your power and give back to the community. Find a Big Red Bus or OneBlood Donor Center location near you. 

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Lauren Frame

Lauren Frame is a Graphic Designer at OneBlood. She has a passion for motivating and educating blood donors through storytelling.

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