Major Key Differences Between White And Red Blood Cells

Blood cells are crucial for various functions in the body including transporting oxygen, protecting against antigen and restoring tissues in the body.

They make up 45% of the blood’s volume with the rest being made up of blood plasma.

Major Key Differences Between White And Red Blood Cells

There is not one common blood cell however, they are divided into several subgroups depending on their specific function and purpose within the body.

Red and white blood cells are among the most important and while they are similar in being cells designed to help function the body and keep it healthy, they work in quite different ways.

Here are the major differences to know between red and white cells, along with how both function and if there are any similarities.

What Are Red Blood Cells?

Also commonly referred to as ‘erythrocytes’, red blood cells work to transport gasses and nutrients throughout the body.

They also help transport carbon dioxide back to our lungs to be exhaled.

Red blood cells are able to carry oxygen due to a protein called hemoglobin which contains iron making the cells red and proteins to help the cell carry and hold oxygen in place as it travels throughout the body.

The production of red blood cells usually occurs if our body does not have enough blood cells or if our body tissue lacks oxygen such as during exercise.

A hormone called erythropoietin will then stimulate the bone marrow to produce more red blood cells.

What Are White Blood Cells?

White blood cells in contrast are a part of our immune system and work to protect our body from infections by fighting them off.

These cells will travel through the bloodstream and tissues to respond to injury and illness by quickly attacking any unknown organism that enters the body.

The way a white cell works is they will first identify the location of an infection while traveling through the body, and will then notify other white cells to their location to work as a protective shield defending the body from further infections.


As mentioned above, while both travel throughout our blood stream, red and white blood cells serve very different functions.

Red cells are designed to transport respiratory gasses including oxygen and carbon dioxide while white cells function as a defensive mechanism for the body fighting off infection and disease.

In order to work in their specific ways, while red blood cells have no need to travel out of the blood vessels, they will therefore stay within the vessels at all times.

In contrast, white blood cells will sometimes come out of blood capillaries to tackle any infections it picks up in the body.


In terms of how both are formed, red blood cells are produced from our red bone marrow.

Because of the lack of a nucleus, red blood cells cannot divide and therefore need to be continually replaced by new cells which are synthesized in the red bone marrow.

White blood cells are also formed in bone marrow to begin with but not red bone marrow.

They are also known to be produced in lymph nodes and the spleen.


When it comes to size, while both cells are extremely small and require a microscope in order to view clearly, red blood cells are actually smaller than white cells with red cells being 7.5um and white cells being 15um on average.

While the different variants of white blood cells often have a more circular shape, red blood cells have more of a flexible disc shape in order to help increase the surface area to volume ratio of the cells making them very small and enabling oxygen and carbon dioxide to diffuse across the red blood cells plasma membrane more readily.

Life Span

Life Span

Both cells will survive for significantly different periods once they are produced and are traveling throughout the body.

While white blood cells can live anywhere from 5 to 21 days, red blood cells are recorded to have an average life span of 120 days.

The actual development of red blood cells from stem cells occurs in about seven days via the process of erythropoiesis.

The formation time for white blood cells is far lower on average being between a few hours and a few days.

Amount In Body

The body contains far less white blood cells than red.

While there are approximately 3,000 to 7,000 white cells in every cubic mm of blood, in contrast there are around 5 million red cells within every cubic mm.

Additionally, while red blood cells take up approximately 45% of blood volume in the body, white cells only make up 1% in comparison.


Red blood cells will be triggered to be produced out of red bone marrow when the body is in need of oxygen, this can include when you’re running or exercising and the body requires oxygen to continue functioning at its best.

The number of red blood cells will also increase in high altitudes and warmer weather.

White blood cells on the other hand increase when there is an indication of an infection in the body and bone marrow is alerted to produce more white cells and send them to the directed area that needs repairing.


Red blood cells acquire their deep red color due to carrying enormous amounts of hemoglobin.

This is an iron containing molecule that binds oxygen as it enters blood vessels in the lungs.

White blood cells on the other hand have no molecules that work to alter its color and so it is colorless without pigment.


Red blood cells do not contain a nucleus, mitochondria or ribosomes.

The absence of these structures makes space for the hundreds of millions of hemoglobin molecules.

Due to their lack of a nucleus, adult red blood cells can also not undergo mitosis and cannot divide or generate new cell structures.

White blood cells in comparison do have a center membrane nucleus within the middle of their round formation.

The nucleus is capable of motility and further helps to defend the body against infections and disease.


White and red blood cells are both extremely important in keeping the body clean and healthy.

While they are of a similar size and are both made from a form of bone marrow, this is essentially where the similarities end as both have many different functions and life spans that are much further apart, not to mention the huge contrast between how much of each is in our body.

They both still serve extremely important purposes however and are vital for keeping our body healthy and functioning at its best.

Jennifer Dawkins

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