Blood is something far greater and more interesting than a liquid that comes out of a person when cut. Blood carries vital chemicals and nutrients throughout the human body. Blood is also considered a form of tissue.
The types of blood cells vary according to shape and function. There are several differences between red blood cells and white blood cells.
TL;DR (Too Long; Didn't Read)
Blood is a fluid tissue containing red and white blood cells. Red and white blood cells have many differences between them, including function and shape.
The Components of Blood
The components of blood include blood cells and plasma. Other materials include proteins, salts, water, sugar and fat. Whole blood refers to blood that courses the veins, arteries and capillaries throughout the body.
The parts of blood include approximately 55 percent plasma and 45 percent blood cells, of which there are three major types.
Types of Blood Cells
The three broad types of blood cells are red blood cells (also called erythrocytes or RBC), white blood cells (WBC) and platelets.
The difference between red blood cells, white blood cells and platelets can be found in their structure, function and prevalence.
Red Blood Cells
More than one difference exists between red and white blood cells. Red blood cells, as their name implies, are red in color. They are also round in shape, yet flat in the middle. A major difference between red blood cells and white blood cells is that there is only one kind of red blood cell.
Red blood cells are far more prominent in the body than white blood cells. RBCs have relatively long lives for blood cells at approximately 120 days in length for healthy red blood cells.
Red blood cells contain the protein hemoglobin (Hgb). Hemoglobin is the storage component of oxygen in red blood cells, starting from when it is breathed in through the lungs. Hemoglobin also returns carbon dioxide waste to the lungs to be exhaled and lends the brilliant red hue to red blood cells. Red blood cells do not contain a nucleus.
Red Blood Cells and Health
Because red blood cells carry oxygen to the body, it is essential that they remain healthy for this function. Adequate nutrition for healthy red blood cells includes a diet fortified with iron, vitamin E and various B vitamins. When red blood cells are not functioning properly, they can lead to disease.
One such disease is anemia. This is when the body has too few red blood cells, meaning there is not enough oxygen being transported to where it is needed. This can lead to fatigue, fainting or even heart failure. Anemia is often caused by a shortage of iron in the diet.
In sickle cell anemia, a genetic disease, red blood cells do not have their characteristic round shape. Rather, they are sickle-shaped, so they cannot move as well through the circulatory system. This leads to other health complications. Sickle cells also do not live nearly as long as normal red blood cells.
Other types of anemia include normocytic anemia, hemolytic anemia and Fanconi anemia.
White Blood Cells
There are far fewer white blood cells in blood than there are red blood cells; the white blood cells make up only about 1 percent of blood. Their functions are vastly different from each other as well. White blood cells are also called leukocytes.
The chief function of white blood cells is that of defense against disease. They are essential to human health. Any time a person falls ill, the various kinds of white blood cells rush to assist in attacking the invading pathogen.
Another interesting function of white blood cells is that they actually consume dead cells, tissues and aging red blood cells.
Types of White Blood Cells
Unlike red blood cells, white blood cells have variations. The five types of white blood cells include:
White Blood Cell Diseases
White blood cells that are too low or high in number may indicate disease. In illnesses such as HIV or cancer, the immune system is weakened, resulting in great risk of infection.
Other illnesses involving white blood cell anomalies include myelodysplastic syndrome and myeloproliferative disorder. Aside from disease, other factors can affect one’s white blood count, such as certain medicines or even stress or pregnancy.
Other Parts of Blood
Another component of blood is the platelet. Platelets are also referred to by their formal name thrombocytes, and they are small pieces of cells. The primary function of platelets is to provide a means of clotting an injured area to stop bleeding. The fibrin that is made in a blood clot gives new tissue a foundation to grow on.
While plasma is not a kind of blood cell, it is the liquid part of blood that helps regulate fluid balance. Plasma is required to move the different kinds of blood cells throughout the circulatory system to deliver nutrients or remove wastes. Plasma also carries hormones and clotting proteins. Plasma makes up about 55 percent of whole blood.
The Functions of Blood
The human body survives because of the components in blood. The general function of blood is to provide a mobile fluid full of oxygen, nutrition, hormones, vitamins, antibodies to disease and even heat to keep people alive.
Blood also serves as a cleaning agent. It removes waste materials from the body such as carbon dioxide, which is then exhaled from the lungs.
Blood travels through the circulatory system via three types of vessels: arteries, veins and capillaries.
Where Is Blood Made?
Blood is made in the marrow of bones. Marrow is the interior portion of bones, and it is the factory of most of the blood cells. Some other areas of the body that produce blood cells include the lymph nodes, spleen and liver.
Immature red blood cells get released into the blood after roughly a week. A kidney-produced hormone called erythropoietin manages their production.
What Is Hematopoiesis?
Hematopoiesis refers to the process of making new blood cells. Beginning as a hematopoietic stem cell, blood cells can differentiate into the various types such as red blood cells, white blood cells and platelets.
Hematopoietic stem cells are primarily made in bone marrow and can also be found in newborn babies’ umbilical cords.
Tests for Blood Health
Doctors can make health care decisions by checking a patient’s blood. One such test is the complete blood count or CBC. This test determines white blood cell count (WBC), red blood cell count (RBC) and platelet count.
Low or high white blood counts, for example, could indicate illness. Other medical tests on blood include hematocrit red blood cell volume (Hct), hemoglobin (Hgb) concentration and differential blood count.
- American Society of Hematology: Blood Basics
- University of Rochester Medical Center: What Are White Blood Cells?
- University of Rochester Medical Center: What Are Red Blood Cells?
- University of Rochester Medical Center: Overview of Blood and Blood Components
- Johns Hopkins Medicine: Facts About Blood
- Texas Heart Institute: Blood
About the Author
J. Dianne Dotson is a science writer with a degree in zoology/ecology and evolutionary biology. She spent nine years working in laboratory and clinical research. A lifelong writer, Dianne is also a content manager and science fiction and fantasy novelist. Dianne features science as well as writing topics on her website, jdiannedotson.com.