What Are Blood Cells? - Functions & Types

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  • 0:02 Introduction to Blood Cells
  • 0:26 Red Blood Cells
  • 1:20 White Blood Cells
  • 3:51 Platelets
  • 4:23 Lesson Summary
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Lesson Transcript
Instructor: Adrianne Baron

Adrianne has taught high school and college biology and has a master's degree in cancer biology.

There are three different types of blood cells circulating through the bloodstream. Learn about the function of each of the three types of blood cells, and test your knowledge by taking the quiz.

Introduction to Blood Cells

Our blood is often referred to as the river of life running through our bodies, but why is this analogy used? Part of the reason for this comparison can be found by exploring the different types of blood cells that flow through this river. There are three main types of blood cells found in the body. These are the erythrocytes, leukocytes and thrombocytes. Let's look at each of these a little closer.

Red Blood Cells

The first type of blood cells are the erythrocytes, or as they are commonly called, red blood cells. These are the most numerous of the three types of blood cells, and they're unique in that they contain no nucleus. Red blood cells function as a transportation system. Think about what happens with a bus. The bus begins a route and picks people up. As the bus continues along the route, people will get off and others will get on at different stops. Eventually, the bus returns to where it started, but not with the same people on the bus. The red blood cells work in a similar way.

Red blood cells pick up oxygen from the lungs and start on a route to the different organs in the body where the oxygen needs to go. After the oxygen is used by the organs, carbon dioxide is produced as a waste product. The red blood cells pick up the carbon dioxide from the organs in the body and take it to the lungs for it to be removed from the body.

White Blood Cells

The next type of blood cell are the leukocytes, also known as white blood cells. These blood cells also have a very important role in the body. They function to protect the body from anything that could harm the body. You can think of the white blood cells as the police officers of the body. The police officers, or white blood cells, patrol the body looking for pathogens, or bad guys, that could harm the body. Just like there are different kinds of police officers, such as patrol officers, detectives, etc., there are different types of white blood cells.

The first type of white blood cell is the lymphocyte. The lymphocytes are further divided into T cells and B cells. Both lymphocytes work together to help your body produce immunity to the different pathogens that have invaded the body. The T cells present the pathogens to the B cells, and then the B cells produce an antibody that can destroy the pathogen. The B cells will remember the antibody that was created for each pathogen, so that it can make the antibody again if the pathogen comes into the body again.

The next type of white blood cell is the monocyte. Monocytes function by phagocytosing, or engulfing the pathogens that come into the body. They can then break the pathogen down into smaller pieces and present the pathogen to the T cells to start the immunity process that we just discussed. The monocytes are unique because of their ability to also leave the blood to go into the organs of the body and protect the organs by eating any pathogens, or anything else, that doesn't belong in the organs.

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