What is in Your Blood?

If red blood cells makeup about 45% of your blood then what is the rest?

The largest component of the blood is plasma. This is the liquid part of your blood. It carries the red blood cells in addition to your white blood cells and platelets through the blood vessels. The plasma fluid itself has electrolytes that are needed for muscle function and proteins that allow the blood to clot.

Your white blood cells are best known for their role in fighting off infection. You have several different types of white blood cells and they are located all throughout your body. They are most notably in your blood stream and lymph nodes. As they travel around your body through your blood they are constantly searching for any sign of infection or injury. When they do find something in your body that shouldn’t be there they “sound the alarm” to bring in more white blood cells and they work together to destroy and get rid of the threat be it a virus, bacteria or injury. White blood cells are formed in the bone marrow and each of the 5 types have a different lifespan.

Platelets are the final part of your blood and when combined with your white blood cells they make up less than one percent of your blood! (The red blood cells that carry oxygen are about 45% of your blood and the plasma that allows the blood cells to move through your vessels make up about 55%). While there may not be as many platelets as other cells they play a very important role in your blood. When your blood vessel gets damaged, for example by a cut, the platelets are the cells that come in and bind together with each other and the proteins in your plasma to form what is called a blood clot and stop the bleeding. Once the clot is no longer needed it will be reabsorbed into your body. Platelets are also made in the bone marrow and they live for about 8 to 10 days.

Now that we understand that red blood cells carry oxygen and get rid of carbon dioxide, and that white blood cells fight infection, platelets help our blood to clot and plasma is the liquid that these cells travel around in. How do they actually get to where they need to go? Let’s talk blood vessels next!